SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUAR Y 2003
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
D
Choice of Memory Organizations
– SN74V263 – 8192 × 18/16384 × 9
– SN74V273 – 16384 × 18/32768 × 9
– SN74V283 – 32768 × 18/65536 × 9
– SN74V293 – 65536 × 18/131072 × 9
D
166-MHz Operation
D
6-ns Read/Write Cycle Time
D
User-Selectable Input and Output Port Bus
Sizing
– ×9 in to ×9 out
– ×9 in to ×18 out
– ×18 in to ×9 out
– ×18 in to ×18 out
D
Big-Endian/Little-Endian User-Selectable
Byte Representation
D
5-V-Tolerant Inputs
D
Fixed, Low First-Word Latency
D
Zero-Latency Retransmit
D
Master Reset Clears Entire FIFO
D
Partial Reset Clears Data, but Retains
Programmable Settings
D
Empty, Full, and Half-Full Flags Signal FIFO
Status
D
Programmable Almost-Empty and
Almost-Full Flags; Each Flag Can Default to
One of Eight Preselected Offsets
D
Selectable Synchronous/Asynchronous
Timing Modes for Almost-Empty and
Almost-Full Flags
D
Program Programmable Flags by Either
Serial or Parallel Means
D
Select Standard Timing (Using EF and FF
Flags) or First-Word Fall-Through (FWFT)
Timing (Using OR and IR Flags)
D
Output Enable Puts Data Outputs in
High-Impedance State
D
Easily Expandable in Depth and Width
D
Independent Read and Write Clocks Permit
Reading and Writing Simultaneously
D
High-Performance Submicron CMOS
Technology
D
Glueless Interface With ’C6x DSPs
D
Available in 80-Pin Thin Quad Flat Pack
(TQFP) and 100-Pin Ball Grid Array (BGA)
Packages
description
The SN74V263, SN74V273, SN74V283, and SN74V293 are exceptionally deep, high-speed, CMOS first-in
first-out (FIFO) memories with clocked read and write controls and a flexible bus-matching ×9/×18 data flow.
There is flexible ×9/×18 bus matching on both read and write ports.
The period required by the retransmit operation is fixed and short.
The first-word data-latency period, from the time the first word is written to an empty FIFO to the time it can be
read, is fixed and short.
These FIFOs are particularly appropriate for network, video, telecommunications, data communications, and
other applications that need to buffer large amounts of data and match buses of unequal sizes.
Each FIFO has a data input port (Dn) and a data output port (Qn), both of which can assume either an 18-bit
or 9-bit width, as determined by the state of external control pins’ input width (IW) and output width (OW) during
the master-reset cycle.
The input port is controlled by write-clock (WCLK) and write-enable (WEN) inputs. Data is written into the FIFO
on every rising edge of WCLK when WEN is asserted. The output port is controlled by read-clock (RCLK) and
read-enable (REN) inputs. Data is read from the FIFO on every rising edge of RCLK when REN is asserted.
An output-enable (OE) input is provided for 3-state control of the outputs.
Copyright 2003, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
2POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PZA PACKAGE
(TOP VIEW)
22 23
RT
OE
VCC
Q17
Q16
GND
GND
Q15
Q14
VCC
Q13
Q12
GND
Q11
GND
Q10
VCC
Q9
Q8
Q7
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
24
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
WEN
SEN
DNC
VCC
DNC
IW
GND
D17
VCC
D16
D15
D14
D13
GND
D12
D11
D10
D9
D8
VCC 25 26 27 28
FSEL1
79 78 77 76 7580 74
MRS
LD
FWFT/SI
FF/IR
PAF
OW
FSEL0
Q0
GND
GND
D5
D4
D3
D2
D1
D0
72 71 7073
29 30 31 32 33
69 68
21
D7
IP
67 66 65 64
34 35 36 37
Q2
Q3
GND
Q4
HF
PAE
PFM
EF/OR
WCLK
PRS
Q5
GND
38 39 40
RM
RCLK
63 62 61
VCC
BE
REN
CC
V
D6
Q1
Q6
DNC = Do not connect
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
B
C
D
E
F
G
H
J
K
1234567 8910
VCC
VCC
VCC
NC
VCC VCC
VCC
VCC
VCC
VCC
NC
WCLK PRS LD GND BE PFM RCLK RT
SEN WEN MRS FF/IR FSEL0 FSEL1 PAE RM REN OE
DNC DNC VCC FWFT/
SI OW HF IP EF/OR Q17
GND GND GND GND GNDIW D17 PAF
NC Q16
D16 D15 GND GND Q15 Q14
D14 D13 GND VCC Q13 Q12
NC D12 D11 VCC Q2 GND GND GND Q11
D10 D9 D5 D1 Q0 GND VCC Q9 Q10
D8 D7 GND GNDD3 Q1 Q3 Q5 Q7 Q8
D6 D4 D2 D0 GND GNDQ4 Q6
DNC = Do not connect
GGM PACKAGE
(TOP VIEW)
A
NC NC
NC NC
description (continued)
The frequencies of both the RCLK and the WCLK signals can vary from 0 to fMAX, with complete independence.
There are no restrictions on the frequency of one clock input with respect to the other.
There are two possible timing modes of operation with these devices: first-word fall-through (FWFT) mode and
standard mode.
In FWFT mode, the first word written to an empty FIFO is clocked directly to the data output lines after three
transitions of the RCLK signal. REN need not be asserted for accessing the first word. However, subsequent
words written to the FIFO do require a low on REN for access. The state of the FWFT/SI input during master
reset determines the timing mode in use.
In standard mode, the first word written to an empty FIFO does not appear on the data output lines unless a
specific read operation is performed. A read operation, which consists of activating REN and enabling a rising
RCLK edge, shifts the word from internal memory to the data output lines.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
4POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
functional block diagram
Write-Control
Logic
RAM Array
8192 ×18 or 16384 ×9
16384 ×18 or 32768 ×9
32768 × 18 or 65536 × 9
65536 × 18 or 131072 × 9
Offset
Register
Input
Register
Flag
Logic
Read Pointer
Read-Control Logic
Output
Register
Write
Pointer
Control
Logic
Reset
Logic
BE
IP
MRS
WEN
WCLK
D0–Dn (×9 or ×18) SEN
HF
PAE
EF/OR
PAF
FF/IR
Q0–Qn (×9 or ×18)
OE RENRCLK
Bus
Configuration
IW
OW
PRS
LD
FSEL1
FSEL0
PFM
FWFT/SI
RM
RT
description (continued)
For applications requiring more data-storage capacity than a single FIFO can provide, the FWFT timing mode
permits depth expansion by chaining FIFOs in series (i.e., the data outputs of one FIFO are connected to the
corresponding data inputs of the next). No external logic is required.
These FIFOs have five flag pins: empty flag or output ready (EF/OR), full flag or input ready (FF/IR), half-full
flag (HF), programmable almost-empty flag (PAE), and programmable almost-full flag (PAF). The IR and OR
functions are selected in FWFT mode. The EF and FF functions are selected in standard mode. HF, PAE, and
PAF always are available for use, regardless of timing mode.
PAE and PAF can be programmed independently to switch at any point in memory. Programmable offsets
determine the flag-switching threshold and can be loaded by parallel or serial methods. Eight default offset
settings also are provided, so that P AE can be set to switch at a predefined number of locations from the empty
boundary. The PAF threshold also can be set at similar predefined values from the full boundary. The default
offset values are set during master reset by the state of FSEL0, FSEL1, and LD.
For serial programming, SEN, together with LD, loads the offset registers via the serial input (SI) on each rising
edge of WCLK. For parallel programming, WEN, together with LD, loads the offset registers via Dn on each
rising edge of WCLK. REN, together with LD, can read the offsets in parallel from Qn on each rising edge of
RCLK, regardless of whether serial or parallel of fset loading has been selected.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
description (continued)
Also, the timing modes of PAE and PAF outputs can be selected. Timing modes can be set to be either
asynchronous or synchronous for PAE and PAF.
If the asynchronous PAE/PAF configuration is selected, PAE is asserted low on the low-to-high transition of
RCLK. PAE is reset to high on the low-to-high transition of WCLK. Similarly, PAF is asserted low on the
low-to-high transition of WCLK, and PAF is reset to high on the low-to-high transition of RCLK.
If the synchronous P AE/PAF configuration is selected , P AE is asserted and updated on the rising edge of RCLK
only and not WCLK. Similarly, PAF is asserted and updated on the rising edge of WCLK only and not RCLK.
The desired mode is configured during master reset by the state of the programmable-flag mode (PFM) pin.
The retransmit function allows data to be reread from the FIFO more than once. A low on the RT input during
a rising RCLK edge initiates a retransmit operation by setting the read pointer to the first location of the memory
array. Zero-latency retransmit timing mode can be selected using the retransmit timing mode (RM). During
master reset, a low on RM selects zero-latency retransmit. A high on RM during master reset selects normal
latency.
If zero-latency retransmit operation is selected, the first data word to be retransmitted is placed on the output
register with respect to the same RCLK edge that initiated the retransmit, if RT is low.
During master reset (MRS), the functions for all the operating modes are programmed. These include FWFT
or standard timing, input bus width, output bus width, big endian or little endian, retransmit mode,
programmable-flag operating and programming method, programmable-flag default offsets, and interspersed
parity select. The read and write pointers are set to the first location of the FIFO. Then, based on the selected
timing mode, EF is set low or OR is set high and FF is set high or IR is set low . Also, PAE is set low, PAF is set
high, and HF is set high. The Q outputs are set low.
Partial reset (PRS) also sets the read and write pointers to the first location of the memory . However , the timing
mode, programmable-flag programming method, default or programmed offset settings, input and output bus
widths, big endian/little endian, interspersed parity select, and retransmit mode existing before partial reset is
asserted remain unchanged. The flags are updated according to the timing mode and offsets in ef fect. PRS is
useful for resetting a device in mid-operation when reprogramming programmable flags and other functions
would be undesirable.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
6POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Read Clock (RCLK)
Read Enable (REN)
Output Enable (OE)
Empty Flag/Output Ready (EF/OR)
Programmable Almost-Empty Flag (PAE)
Write Clock (WCLK)
SN74V263
SN74V273
SN74V283
SN74V293
Retransmit (RT)
Half-Full Flag (HF)
Interspersed/Noninterspersed Parity (IP)
(×9 or ×18) Data Out (Q0–Qn)
Big Endian/Little Endian (BE)
Write Enable (WEN)
Load (LD)
(×9 or ×18) Data In (D0–Dn)
Serial Enable (SEN)
First-Word Fall-Through or Serial Input
(FWFT/SI)
Full Flag/Input Ready (FF/IR)
Programmable Almost-Full Flag (PAF)
Input Width
(IW) Output Width
(OW)
Partial Reset (PRS) Master Reset (MRS)
Figure 1. Single-Device-Configuration Signal Flow
description (continued)
A big-endian/little-endian data word format is provided. This function is useful when data is written into the FIFO
in long-word (×18) format and read out of the FIFO in small-word (×9) format. If big-endian mode is selected,
the most significant byte (MSB) (word) of the long word written into the FIFO is read out of the FIFO first, followed
by the least significant byte (LSB). If little-endian format is selected, the LSB of the long word written into the
FIFO is read out first, followed by the MSB. The mode desired is configured during master reset by the state
of the big-endian/little-endian (BE) pin.
The interspersed/noninterspersed parity (IP) bit function allows the user to select the parity bit in the word loaded
into the parallel port (D0–Dn) when programming the flag offsets. If interspersed-parity mode is selected, the
FIFO assumes that the parity bit is located in bit position D8 during the parallel programming of the flag offsets.
If noninterspersed-parity mode is selected, D8 is assumed to be a valid bit and D16 and D17 are ignored. IP
mode is selected during master reset by the state of the IP input pin. This mode is relevant only when the input
width is set to ×18 mode.
The SN74V263, SN74V273, SN74V283, and SN74V293 are fabricated using TI’s high-speed submicron
CMOS technology.
For more information on this device family, see the following application reports:
D
Interfacing TI High-Speed External FIFOs With TI DSP Via DSPs’ External Memory Interface (EMIF)
(literature number SPRA534)
D
Interfacing TI High-Speed External FIFOs With TI DSP Via DSPs’ Expansion Bus (XBus) (literature number
SPRA547)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Table 1. Bus-Matching Configuration Modes
IW OW WRITE PORT WIDTH READ PORT WIDTH
L L ×18 ×18
L H ×18 ×9
H L ×9×18
H H ×9×9
Terminal Functions
TERMINAL
I/O
DESCRIPTION
NAME
I/O
DESCRIPTION
BE I Big endian/little endian. During master reset, a low on BE selects big-endian operation. A high on BE during master
reset selects little-endian format.
D0–D17 I Data inputs. Data inputs for an 18- or 9-bit bus. When in 18-bit mode, D0–D17 are used. When in 9-bit mode, D0–D8
are used and the unused inputs (D9–D17) should be tied low.
EF/OR O Empty flag/output ready. In FWFT mode, the OR function is selected. OR indicates whether there is valid data
available at the outputs. In the standard mode, the EF function is selected. EF indicates whether the FIFO memory
is empty.
FF/IR O Full flag/input ready. In FWFT mode, the IR function is selected. IR indicates whether there is space available for
writing to the FIFO memory. In standard mode, the FF function is selected. FF indicates whether the FIFO memory
is full.
FSEL0 I Flag-select bit 0. During master reset, FSEL0, along with FSEL1 and LD, selects the default of fset values for PAE
and PAF. Up to eight possible settings are available.
FSEL1 I Flag-select bit 1. During master reset, FSEL1, along with FSEL0 and LD, selects the default of fset values for PAE
and PAF. Up to eight possible settings are available.
FWFT/SI I First-word fall-through/serial in. During master reset, FWFT/SI selects FWFT or standard mode. After master reset,
FWFT/SI functions as a serial input for loading of fset registers.
HF O Half-full flag. HF indicates whether the FIFO memory is more or less than half full.
IP I Interspersed parity. During master reset, a low on IP selects noninterspersed-parity mode. A high on IP selects
interspersed-parity mode.
IW I Input width. IW selects the bus width of the write port. During master reset, when IW is low, the write port is configured
with a ×18 bus width. If IW is high, the write port is a ×9 bus width.
LD I
Load. This is a dual-purpose pin. During master reset, the state of the LD input, along with FSEL0 and FSEL1,
determines one of eight default offset values for the P AE and P AF flags, along with the method by which these offset
registers can be programmed, parallel or serial (see Table 2). After master reset, LD enables writing to and reading
from the offset registers.
MRS I
Master reset. MRS initializes the read and write pointers to zero and sets the output register to all zeroes. During
master reset, the FIFO is configured for either FWFT or standard mode, bus-matching configurations, one of eight
programmable-flag default settings, serial or parallel programming of the offset settings, big-endian/little-endian
format, zero- or normal-latency retransmit, interspersed parity, and synchronous versus asynchronous
programmable-flag timing modes.
OE I Output enable. OE controls the output impedance of Qn.
OW I Output width. OW selects the bus width of the read port. During master reset, when OW is low, the read port is
configured with a ×18 bus width. If OW is high, the read port is a ×9 bus width.
PAE OProgrammable almost-empty flag. PAE goes low if the number of words in the FIFO memory is less than or equal
to offset n, which is stored in the empty offset register. PAE goes high if the number of words in the FIFO memory
is greater than offset n. Add one if PAE is in FWFT mode.
PAF OProgrammable almost-full flag. PAF goes high if the number of free locations in the FIFO memory is more than
offset m, which is stored in the full offset register. PAF goes low if the number of free locations in the FIFO memory
is less than or equal to m.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
8POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Terminal Functions (Continued)
TERMINAL
I/O
DESCRIPTION
NAME
I/O
DESCRIPTION
PFM I Programmable-flag mode. During master reset, a low on PFM selects asynchronous programmable-flag timing
mode. A high on PFM selects synchronous programmable-flag timing mode.
PRS I
Partial reset. PRS initializes the read and write pointers to zero and sets the output register to all zeroes. During
partial reset, the existing mode (standard or FWFT), programming method (serial or parallel), and
programmable-flag settings, input and output bus widths, big/little endian, interspersed parity select, and retransmit
mode are all retained.
Q0–Q17 O Data outputs. Data outputs for a 18- or 9-bit bus. When in 18-bit mode, Q0–Q17 are used and when in 9-bit mode,
Q0–Q8 are used, and the unused outputs, Q9–Q17 should not be connected. Outputs are not 5-V tolerant regardless
of the state of OE.
RCLK I Read clock. When enabled by REN, the rising edge of RCLK reads data from the FIFO memory and offsets from
the programmable registers.
REN I Read enable. REN enables RCLK for reading data from the FIFO memory and offset registers.
RM I Retransmit latency mode. During master reset, a low on RM selects zero-latency retransmit timing mode. A high on
RM selects normal-latency mode.
RT IRetransmit. RT asserted on the rising edge of RCLK initializes the READ pointer to zero, sets the EF flag to low (OR
to high in FWFT mode) and does not disturb the write pointer, programming method, existing timing mode, or
programmable flag settings. RT is useful to reread data starting from the first physical location of the FIFO.
SEN I Serial enable. SEN enables serial loading of programmable flag offsets.
WCLK I Write clock. When enabled by WEN, the rising edge of WCLK writes data into the FIFO and offsets into the
programmable registers for parallel programming and, when enabled by SEN, the rising edge of WCLK writes one
bit of data into the programmable register for serial programming.
WEN I Write enable. WEN enables WCLK for writing data into the FIFO memory and offset registers.
detailed description
inputs
data in (D0–Dn)
Data inputs for 18-bit-wide data (D0–D17) or data inputs for 9-bit wide data (D0–D8).
controls
master reset (MRS)
A master reset is accomplished when the MRS input is taken to a low state. This operation sets the internal read
and write pointers to the first location of the RAM array. PAE goes low, PAF goes high, and HF goes high.
If FWFT/SI is high, the FWFT mode, along with IR and OR, is selected. OR goes high and IR goes low. If
FWFT/SI is low during master reset, the standard mode, along with EF and FF, is selected. EF goes low and
FF goes high.
All control settings, such as OW, IW, BE, RM, PFM, and IP, are defined during the master reset cycle.
During a master reset, the output register is initialized to all zeroes. A master reset is required after power up,
before a write operation can take place. MRS is asynchronous.
See Figure 5 for timing information.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
partial reset (PRS)
A partial reset is accomplished when the PRS input is taken to a low state. As in the case of the master reset,
the internal read and write pointers are set to the first location of the RAM array , PAE goes low , PAF goes high,
and HF goes high.
Whichever mode is active at the time of partial reset remains selected (FWFT or standard mode). If FWFT mode
is active, OR goes high and IR goes low. If the standard mode is active, FF goes high and EF goes low.
Following partial reset, all values held in the offset registers remain unchanged. The programming method
(parallel or serial) active at the time of partial reset also is retained. The output register is initialized to all zeroes.
PRS is asynchronous.
A partial reset is useful for resetting the device during operation, when reprogramming programmable-flag offset
settings might not be convenient.
See Figure 6 for timing information.
retransmit (RT)
The retransmit operation allows previously read data to be accessed again. There are two modes of retransmit
operation: normal latency and zero latency. There are two stages to retransmit. The first stage is a setup
procedure that resets the read pointer to the first location of memory . The second stage is the actual retransmit,
which consists of reading out the memory contents, starting at the beginning of the memory.
Retransmit setup is initiated by holding RT low during a rising RCLK edge. REN and WEN must be high before
RCLK rises when R T is low. When zero latency is used, REN need not be high before RCLK rises while RT is
low.
If FWFT mode is selected, the FIFO marks the beginning of the retransmit setup by setting OR high. During this
period, the internal read pointer is set to the first location of the RAM array.
When OR goes low , retransmit setup is complete; at the same time, the contents of the first location appear on
the outputs. Because FWFT mode is selected, the first word appears on the outputs and no low on REN is
necessary. Reading all subsequent words requires a low on REN to enable the rising edge of RCLK.
See Figure 12 for timing information.
If standard mode is selected, the FIFO marks the beginning of the retransmit setup by setting EF low. The
change in level is noticeable only if EF was high before setup. During this period, the internal read pointer is
initialized to the first location of the RAM array.
When EF goes high, retransmit setup is complete and read operations can begin, starting with the first location
in memory. Since standard mode is selected, every word read, including the first word following retransmit
setup, requires a low on REN to enable the rising edge of RCLK.
See Figure 11 for timing information.
In retransmit operation, the zero-latency mode can be selected using the retransmit latency mode (RM) pin
during a master reset. This can be applied to the standard mode and the FWFT mode.
retransmit latency mode (RM)
A zero-latency retransmit timing mode can be selected using RM. During master reset, a low on RM selects
zero-latency retransmit. A high on RM during master reset selects normal latency.
If zero-latency retransmit operation is selected, the first data word to be retransmitted is placed on the output
register with respect to the same RCLK edge that initiated the retransmit based on RT being low.
See Figures 13 and 14 for timing information.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
10 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
first-word fall-through/serial in (FWFT/SI)
FWFT/SI is a dual-purpose pin. During master reset, the state of the FWFT/SI input determines whether the
device operates in FWFT mode or standard mode.
If, at the time of master reset, FWFT/SI is high, FWFT mode is selected. This mode uses OR to indicate whether
there is valid data at the data outputs (Qn). It also uses IR to indicate whether the FIFO memory has any free
space for writing. In the FWFT mode, the first word written to an empty FIFO goes directly to Qn after three RCLK
rising edges; REN = low is not necessary. Subsequent words must be accessed using REN and RCLK.
If, at the time of master reset, FWFT/SI is low, standard mode is selected. This mode uses EF to indicate whether
there are any words present in the FIFO memory . It also uses the FF to indicate whether the FIFO memory has
any free space for writing. In standard mode, every word read from the FIFO, including the first, must be
requested using REN and RCLK.
After master reset, FWFT/SI acts as a serial input for loading PAE and PAF offsets into the programmable
registers. The serial input function can be used only when the serial loading method is selected during master
reset. Serial programming using the FWFT/SI pin functions the same way in both FWFT and standard modes.
write clock (WCLK)
A write cycle is initiated on the rising edge of the WCLK input. Data setup and hold times must be met, with
respect to the low-to-high transition of WCLK. It is permissible to stop WCLK. Note that while WCLK is idle, the
FF/IR, P AF, and HF flags are not updated. (WCLK is capable only of updating the HF flag to low .) The write and
read clocks can be either independent or coincident.
write enable (WEN)
When WEN is low, data can be loaded into the FIFO RAM array on the rising edge of every WCLK cycle if the
device is not full. Data is stored in the RAM array sequentially and independently of any ongoing read operation.
When WEN is high, no new data is written in the RAM array on each WCLK cycle.
To prevent data overflow in the FWFT mode, IR goes high, inhibiting further write operations. After completion
of a valid read cycle, IR goes low, allowing a write to occur. The IR flag is updated by two WCLK cycles + tsk
after the valid RCLK cycle.
T o prevent data overflow in the standard mode, FF goes low , inhibiting further write operations. After completion
of a valid read cycle, FF goes high, allowing a write to occur . The FF is updated by two WCLK cycles + tsk after
the RCLK cycle.
WEN is ignored when the FIFO is full in either FWFT or standard modes.
read clock (RCLK)
A read cycle is initiated on the rising edge of the RCLK input. Data can be read on the outputs, on the rising edge
of the RCLK input. It is permissible to stop RCLK. While RCLK is idle, the EF/OR, PAE and HF flags are not
updated. RCLK is capable only of updating the HF flag to high. The write and read clocks can be independent
or coincident.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
11
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
read enable (REN)
When REN is low , data is loaded from the RAM array into the output register on the rising edge of every RCLK
cycle, if the device is not empty.
When REN is high, the output register holds the previous data and no new data is loaded into the output register.
The data outputs Q0–Qn maintain the previous data value.
In the FWFT mode, the first word written to an empty FIFO automatically goes to the outputs Qn on the third
valid low-to-high transition of RCLK + tsk after the first write. REN does not need to be asserted low . To access
all other words, a read must be executed using REN. The RCLK low-to-high transition after the last word has
been read from the FIFO, OR goes high with a true read (RCLK with REN = low), inhibiting further read
operations. REN is ignored when the FIFO is empty.
In the standard mode, every word accessed at Qn, including the first word written to an empty FIFO, must be
requested using REN. When the last word has been read from the FIFO, EF goes low, inhibiting further read
operations. REN is ignored when the FIFO is empty. Once a write is performed, EF goes high, allowing a read
to occur. The EF flag is updated by two RCLK cycles + tsk after the valid WCLK cycle.
serial enable (SEN)
The SEN input is an enable used only for serial programming of the offset registers. The serial programming
method must be selected during master reset. SEN always is used with LD. When these lines are both low, data
at the SI input can be loaded into the program register, with one bit for each low-to-high transition of WCLK.
When SEN is high, the programmable registers retain the previous settings and no offsets are loaded. SEN
functions the same way in FWFT and standard modes.
output enable (OE)
When OE is asserted (low), the parallel output buffers receive data from the output register. When OE is high,
the output data bus (Qn) goes into the high-impedance state.
load (LD)
LD is a dual-purpose pin. During master reset, the state of the LD input, along with FSEL0 and FSEL1,
determines one of eight default offset values for the PAE and PAF flags, along with the method by which these
offset registers can be programmed, parallel or serial (see Table 2). After master reset, LD enables write
operations to and read operations from the offset registers. Only the of fset loading method currently selected
can be used to write to the registers. Offset registers can be read only in parallel.
After master reset, LD is used to activate the programming process of the flag offset values P AE and PAF . Pulling
LD low begins a serial loading, or a parallel load, or a read of these offset values.
input width (IW)/output width (OW) bus matching
IW and OW define the input and output bus widths. During master reset, the state of these pins is used to
configure the device bus sizes (see Table 1 for control settings). All flags operate based on the word/byte size
boundary, as defined by the selection of the widest input or output bus width.
big endian/little endian (BE)
During master reset, a low on BE selects big-endian operation. A high on BE during master reset selects
little-endian format. This function is useful when data is written into the FIFO in word format (×18) and read out
of the FIFO in word format (×18) or byte format (×9). If big-endian mode is selected, the MSB of the word written
into the FIFO is read out of the FIFO first, followed by the LSB. If little-endian format is selected, the LSB of the
word written into the FIFO is read out first, followed by the MSB. The desired mode is configured during master
reset by the state of the BE.
See Figure 4 for the byte arrangement.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
12 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
programmable-flag mode (PFM)
During master reset, a low on PFM selects asynchronous programmable-flag timing mode. A high on PFM
selects synchronous programmable-flag timing mode. If asynchronous PAF/PAE configuration is selected
(PFM low during MRS), PAE is asserted low on the low-to-high transition of RCLK. PAE is reset to high on the
low-to-high transition of WCLK. Similarly, PAF is asserted low on the low-to-high transition of WCLK, and PAF
is reset to high on the low-to-high transition of RCLK.
If the synchronous PAE/PAF configuration is selected (PFM high during MRS), PAE is asserted and updated
on the rising edge of RCLK only, and not WCLK. Similarly, PAF is asserted and updated on the rising edge of
WCLK only, and not RCLK. The mode desired is configured during master reset by the state of PFM.
interspersed parity (IP)
During master reset, a low on IP selects noninterspersed-parity mode. A high selects interspersed-parity mode.
The IP bit function allows the user to select the parity bit in the word loaded into the parallel port (D0–Dn) when
programming the flag offsets. If interspersed-parity mode is selected, the FIFO assumes that the parity bit is
located in bit positions D8 and D17 during the parallel programming of the flag offsets and, therefore, ignores
D8 when loading the offset register in parallel mode. This also is applied to the output register when reading
the value of the offset register. If interspersed parity is selected, output Q8 is invalid. If noninterspersed-parity
mode is selected, D16 and D17 are the parity bits and are ignored during parallel programming of the offsets
(D8 becomes a valid bit). Additionally, output Q8 becomes a valid bit when performing a read of the offset
register. Interspersed-parity mode is selected during master reset by state of IP.
outputs
full flag/input ready (FF/IR)
FI/IR is a dual-purpose pin. In FWFT mode, the IR function is selected. IR goes low when memory space is
available for writing in data. When there is no longer any free space left, IR goes high, inhibiting further write
operations. If no reads are performed after a reset (either MRS or PRS), IR goes high after D writes to the FIFO.
If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the SN74V273,
D = 32769 for the SN74V283, and D = 65537 for the SN74V293. If both ×9 input and ×9 output bus widths are
selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283, and
D = 131073 for the SN74V293.
See Figure 9 for timing information.
In standard mode, the FF function is selected. When the FIFO is full, FF goes low, inhibiting further write
operations. When FF is high, the FIFO is not full. If no reads are performed after a reset (either MRS or PRS),
FF goes low after D writes to the FIFO. If ×18 input or ×18 output bus width is selected, D = 8192 for the
SN74V263, D = 16384 for the SN74V273, D = 32768 for the SN74V283, and D = 65536 for the SN74V293. If
both ×9 input and ×9 output bus widths are selected, D = 16384 for the SN74V263, D = 32768 for the SN74V273,
D = 65536 for the SN74V283, and D = 131072 for the SN74V293.
See Figure 7 for timing information.
The IR status not only measures the contents of the FIFO memory, but also counts the presence of a word in
the output register. Thus, in FWFT mode, the total number of writes necessary to deassert IR is one greater than
needed to assert FF in standard mode.
FF/IR is synchronous and updated on the rising edge of WCLK. FF/IR are double register-buffered outputs.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
13
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
empty flag/output ready (EF/OR)
EF/OR is a dual-purpose pin. In FWFT mode, the OR function is selected. OR goes low at the same time that
the first word written to an empty FIFO appears valid on the outputs. OR stays low after the RCLK low-to-high
transition that shifts the last word from the FIFO memory to the outputs. OR goes high only with a true read
(RCLK with REN = low). The previous data stays at the outputs, indicating the last word was read. Further data
reads are inhibited until OR goes low again.
See Figure 10 for timing information.
In the standard mode, the EF function is selected. When the FIFO is empty , EF goes low , inhibiting further read
operations. When EF is high, the FIFO is not empty.
See Figure 8 for timing information.
EF/OR is synchronous and updated on the rising edge of RCLK.
In FWFT mode, OR is a triple register-buffered output. In standard mode, EF is a double register-buffered
output.
programmable almost-full flag (PAF)
PAF goes low when the FIFO reaches the almost-full condition. In FWFT mode, if ×18 input or ×18 output bus
width is selected, PAF goes low after (8193 – m) writes for the SN74V263, (16385 – m) writes for the SN74V273,
(32769 – m) writes for the SN74V283, and (65537 – m) writes for the SN74V293. If both ×9 input and ×9 output
bus widths are selected, PAF goes low after (16385 – m) writes for the SN74V263, (32769 – m) writes for the
SN74V273, (65537 – m) writes for the SN74V283, and (131073 – m) writes for the SN74V293. The offset m
is the full offset value. The default setting for this value is shown in Table 2.
In standard mode, if no reads are performed after MRS, PAF goes low after (D – m) words are written to the
FIFO. If ×18 input or ×18 output bus width is selected, (D – m) = (8192 – m) writes for the SN74V263, (16384 – m)
writes for the SN74V273, (32768 – m) writes for the SN74V283, and (65536 – m) writes for the SN74V293. If
both ×9 input and ×9 output bus widths are selected, (D – m) = (16384 – m) writes for the SN74V263,
(32768 – m) writes for the SN74V273, (65536 – m) writes for the SN74V283, and (131072 – m) writes for the
SN74V293. The offset m is the full offset value. The default setting for this value is shown in Table 2.
See Figure 18 for timing information.
If asynchronous PAF configuration is selected, the PAF is asserted low on the low-to-high transition of WCLK.
PAF is reset to high on the low-to-high transition of RCLK. If synchronous PAF configuration is selected, the PAF
is updated on the rising edge of WCLK (see Figure 20).
programmable almost-empty flag (PAE)
PAE goes low when the FIFO reaches the almost-empty condition. In FWFT mode, PAE goes low when there
are n + 1 words, or fewer, in the FIFO. The default setting for this value is shown in Table 2.
In standard mode, P AE goes low when there are n words, or fewer , in the FIFO. The of fset n is the empty offset
value. The default setting for this value is shown in Table 2.
See Figure 19 for timing information.
If asynchronous PAE configuration is selected, PAE is asserted low on the low-to-high transition of the read clock
(RCLK). PAE is reset to high on the low-to-high transition of the write clock (WCLK). If synchronous PAE
configuration is selected, PAE is updated on the rising edge of RCLK.
See Figure 21 for timing information.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
14 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
half-full flag (HF)
The HF output indicates a half-full FIFO. The rising WCLK edge that fills the FIFO beyond half-full sets HF low .
The flag remains low until the difference between the write and read pointers becomes less than or equal to half
of the total depth of the device. The rising RCLK edge that accomplishes this condition sets HF high.
In FWFT mode, if no reads are performed after reset (MRS or PRS), HF goes low after [(D – 1)/2] + 2 writes
to the FIFO. If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the
SN74V273, D = 32769 for the SN74V283, and D = 65537 for the SN74V293. If both ×9 input and ×9 output bus
widths are selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283,
and D = 131073 for the SN74V293.
In standard mode, if no reads are performed after reset (MRS or PRS), HF goes low after (D/2) + 1 writes to
the FIFO. If ×18 input or ×18 output bus width is selected, D = 8192 for the SN74V263, D = 16384 for the
SN74V273, D = 32768 for the SN74V283, and D = 65536 for the SN74V293. If both ×9 input and ×9 output bus
widths are selected, D = 16384 for the SN74V263, D = 32768 for the SN74V273, D = 65536 for the SN74V283,
and D = 131072 for the SN74V293.
See Figure 22 for timing information. Because HF is updated by both RCLK and WCLK, it is considered
asynchronous.
data outputs (Q0–Qn)
Q0–Q17 are data outputs for 18-bit-wide data or Q0–Q8 are data outputs for 9-bit-wide data.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
15
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)†
Terminal voltage range with respect to GND, VTERM –0.5 V to 4.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous output current, IO (VO = 0 to VCC) ±50 mA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, Tstg –55°C to 125°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
†Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only , and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may af fect device reliability.
recommended operating conditions
MIN TYP MAX UNIT
VCC Supply voltage (see Note 1) 3.15 3.3 3.45 V
GND Supply voltage 0 0 0 V
VIH High-level input voltage (see Note 2) 2 5.5 V
VIL Low-level input voltage 0.8 V
TAOperating free-air temperature 0 70 °C
NOTES: 1. VCC = 3.3 V ± 0.15 V, JESD8-A compliant
2. Outputs are not 5-V tolerant.
electrical characteristics over recommended operating conditions (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN MAX UNIT
VOH IOH = –2 mA 2.4 V
VOL IOL = 8 mA 0.4 V
IIVI = 0.4 V to VCC ±1µA
IOZ OE ≥ VIH, VO = 0.4 V to VCC ±10 µA
ICC1 ×9 input to ×9 output, See Notes 3, 4, and 5 30 mA
ICC2 ×18 input to ×18 output, See Notes 3, 4, and 5 35 mA
ICC3 Standby, See Notes 3 and 6 15 mA
CIN VI = 0, TA = 25°C, f = 1 MHz 10 pF
COUT VO = 0, TA = 25°C, f = 1 MHz, Output deselected (OE ≥ VIH) 10 pF
NOTES: 3. Tested with outputs open (IOUT = 0)
4. RCLK and WCLK switch at 20 MHz and data inputs switch at 10 MHz.
5. For ×18 bus widths, typical ICC2 = 5 + fS + 0.02 ×CL ×fS (in mA); for ×9 bus widths, typical ICC1 = 5 + 0.775 fS + 0.02 ×CL ×fS (in
mA). These equations are valid under the following conditions:
VCC = 3.3 V , T A = 25°C, fS = WCLK frequency = RCLK frequency (in MHz, using TTL levels), data switching at fS/2, CL = capacitive
load (in pF).
6. All inputs = (VCC – 0.2 V) or (GND + 0.2 V), except RCLK and WCLK, which switch at 20 MHz.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
16 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
timing requirements over recommended ranges of supply voltage and operating free-air
temperature (see Figure 2 through Figure 22)†
SN74V263-6
SN74V273-6
SN74V283-6
SN74V293-6
SN74V263-7.5
SN74V273-7.5
SN74V283-7.5
SN74V293-7.5
SN74V263-10
SN74V273-10
SN74V283-10
SN74V293-10
SN74V263-15
SN74V273-15
SN74V283-15
SN74V293-15 UNIT
MIN MAX MIN MAX MIN MAX MIN MAX
fclock Clock cycle frequency 166 133 100 66.7 MHz
tAData access time 2 4.5 2 5 2 6.5 2 10 ns
tCLK Clock cycle time 6 7.5 10 15 ns
tCLKH Clock high time 2.5 3.5 4.5 6 ns
tCLKL Clock low time 2.5 3.5 4.5 6 ns
tDS Data setup time 1.5 2.5 3.5 4 ns
tDH Data hold time 0.5 0.5 0.5 1 ns
tENS Enable setup time 1.5 2.5 3.5 4 ns
tENH Enable hold time 0.5 0.5 0.5 1 ns
tLDS Load setup time 2 3.5 3.5 4 ns
tLDH Load hold time 0 0.5 0.5 1 ns
tRS Reset pulse duration‡10 10 10 15 ns
tRSS Reset setup time 15 15 15 15 ns
tRSR Reset recovery time 10 10 10 15 ns
tRSF Reset to flag and output time 15 15 15 15 ns
tRTS Retransmit setup time 2 3.5 3.5 4 ns
tOLZ Output enable to output in low impedance 0 0 0 0 ns
tOE Output enable to output valid 2 4.5 2 6 2 6 2 8 ns
tOHZ Output enable to output in high impedance 2 4.5 2 6 2 6 2 8 ns
tWFF Write clock to FF or IR 4.5 5 6.5 10 ns
tREF Read clock to EF or OR 4.5 5 6.5 10 ns
tPAFA Clock to asynchronous programmable
almost-full flag 8.5 12.5 16 20 ns
tPAFS Write clock to synchronous programmable
almost-full flag 4.5 5 6.5 10 ns
tPAEA Clock to asynchronous programmable
almost-empty flag 8.5 12.5 16 20 ns
tPAES Read clock to synchronous programmable
almost-empty flag 4.5 5 6.5 10 ns
tHF Clock to half-full flag 7 12.5 16 20 ns
tsk1 Skew time between read clock and write clock
for EF/OR and FF/IR 4 5 7 9 ns
tsk2 Skew time between read clock and write clock
for PAE and PAF 4 7 10 14 ns
†All ac timings apply to both FWFT mode and standard modes.
‡Pulse durations less than minimum values are not allowed.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
17
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PARAMETER MEASUREMENT INFORMATION
From Output
Under Test
30 pF
(see Note B)
510 Ω
330 Ω
3.3 V
Input Pulse Levels
Input Rise/Fall Times
Input Timing Reference Levels
Output Reference Levels
Output Load for tCLK = 10 ns, 15 ns
Output Load for tCLK = 7.5 ns
GND to 3.0 V
3 ns (see Note A)
1.5 V
1.5 V
See A
See B and C
AC TEST CONDITIONS
50 Ω
VCC/2
ZO = 50 Ω
I/O
B. AC TEST LOAD
FOR 6- AND 7.5-SPEED GRADE
A. OUTPUT LOAD CIRCUIT FOR 10- AND 15-SPEED GRADES
0
1
2
3
4
5
6
0 20 40 60 80 100 120 140 160 180 200
C. LUMPED CAPACITIVE LOAD, TYPICAL DERATING
Capacitance – pF
Typical t∆CD – ns
NOTES: A. For 133-MHz and 166-MHz operation, input rise/fall times are 1.5 ns.
B. Includes probe and jig capacitance
Figure 2. Load Circuits
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
18 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
functional description
timing modes: FWFT mode vs standard mode
The SN74V263, SN74V273, SN74V283, and SN74V293 support two different timing modes of operation:
FWFT or standard. The selection of the mode is determined during master reset by the state of FWFT/SI.
If, at the time of master reset, FWFT/SI is high, then FWFT mode is selected. This mode uses OR to indicate
whether there is valid data at the data outputs (Qn). It also uses IR to indicate whether the FIFO has any free
space for writing. In the FWFT mode, the first word written to an empty FIFO goes directly to Qn after three RCLK
rising edges; REN = low is not necessary. Subsequent words must be accessed using REN and RCLK.
If, at the time of master reset, FWFT/SI is low , then standard mode is selected. This mode uses EF to indicate
whether there are any words present in the FIFO. It also uses the FF function to indicate whether the FIFO has
any free space for writing. In standard mode, every word read from the FIFO, including the first, must be
requested, using REN and RCLK.
Various signals (both input and output) operate differently, depending on which timing mode is in effect.
FWFT mode
In FWFT mode, status flags IR, PAF , HF, PAE, and OR operate as outlined in T able 4. T o write data into the FIFO,
WEN must be low. Data presented to the DATA IN lines is clocked into the FIFO on subsequent transitions of
WCLK. After the first write is performed, the OR flag goes low after three low-to-high transitions on RCLK.
Subsequent writes continue to fill up the FIFO. P AE goes high after n + 2 words have been loaded into the FIFO,
where n is the empty offset value. The default setting for these values is in the footnote of T able 2. This parameter
also is user programmable (see the programmable-flag offset loading section).
If one continues to write data into the FIFO and assumes no read operations are taking place, HF switches to
low after the [(D – 1)/2 + 2] words were written into the FIFO. If ×18 input or ×18 output bus width is selected,
[(D – 1)/2 + 2] = 4098th word for the SN74V263, 8194th word for SN74V273, 16386th word for the SN74V283,
and 32770th word for the SN74V293. If both ×9 input and ×9 output bus widths are selected,
[(D – 1)/2 + 2] = 8194th word for the SN74V263, 16386th word for SN74V273, 32770th word for the SN74V283,
and 65,538th word for the SN74V293. Continuing to write data into the FIFO causes PAF to go low. Again, if
no reads are performed, the P AF goes low after (D – m) writes to the FIFO. If ×18 input or ×18 output bus width
is selected, (D – m) = (8193 – m) writes for the SN74V263, (16385 – m) writes for the SN74V273, (32769 – m)
writes for the SN74V283, and (65537 – m) writes for the SN74V293. If both ×9 input and ×9 output bus widths
are selected, (D – m) = (16385 – m) writes for the SN74V263, (32769 – m) writes for the SN74V273, (65537 – m)
writes for the SN74V283, and (131073 – m) writes for the SN74V293. The offset m is the full of fset value. The
default settings for these values are given in the footnote of Table 2.
When the FIFO is full, the IR flag goes high, inhibiting further write operations. If no reads are performed after
a reset, IR goes high after D writes to the FIFO. If ×18 input or ×18 output bus width is selected, D = 8193 writes
for the SN74V263, D = 16385 writes for the SN74V273, D = 32769 writes for the SN74V283, and D = 65537
writes for the SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16385 writes for the
SN74V263, D = 32769 writes for the SN74V273, D = 65537 writes for the SN74V283, and D = 131073 writes
for the SN74V293. Note that the additional word in FWFT mode is due to the capacity of the memory plus output
register.
If the FIFO is full, the first read operation cause the IR flag to go low after two low-to-high transitions of WCLK.
Subsequent read operations causes the PAF and HF to go high at the conditions shown in Table 4. If further
read operations occur without write operations, PAE goes low when there are n + 1 words in the FIFO, where
n is the empty offset value. Continuing read operations causes the FIFO to become empty. When the last word
has been read from the FIFO, OR goes high, inhibiting further read operations. REN is ignored when the FIFO
is empty.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
19
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
FWFT mode (continued)
When configured in FWFT mode, the OR flag output is triple register buffered, and the IR flag output is double
register buffered.
Timing diagrams for FWFT mode can be found in Figures 9, 10, and 12.
standard mode
In this mode, status flags FF , P AF , HF, P AE, and EF operate as outlined in T able 3. To write data into to the FIFO,
WEN must be low. Data presented to the DATA IN lines is clocked into the FIFO on subsequent transitions of
WCLK. After the first write is performed, EF goes high after two low-to-high transitions on RCLK. Subsequent
writes continue to fill up the FIFO. PAE goes high after n + 1 words have been loaded into the FIFO, where n
is the empty offset value. The default setting for these values is in the footnote of Table 2. This parameter also
is user programmable (see the programmable-flag offset loading section).
If one continues to write data into the FIFO and assumes no read operations are taking place, HF switches to
low after (D/2 + 1) words are written into the FIFO. If ×18 input or ×18 output bus width is selected,
(D/2 + 1) = 4097th word for the SN74V263, 8193th word for the SN74V273, 16385th word for the SN74V283,
and 32769th word for the SN74V293. If both ×9 input and ×9 output bus widths are selected,
(D/2 + 1) = 8193rd word for the SN74V263, 16385th word for the SN74V273, 32769th word for the SN74V283,
and 65537th word for the SN74V293. Continuing to write data into the FIFO causes P AF to go low . Again, if no
reads are performed, PAF goes low after (D – m) writes to the FIFO. If ×8 input or ×18 output bus width is
selected, (D – m) = (8192 – m) writes for the SN74V263, (16384 – m) writes for the SN74V273, (32768 – m)
writes for the SN74V283, and (65536 – m) writes for the SN74V293. If both ×9 input and ×9 output bus widths
are selected, (D – m) = (16384 – m) writes for the SN74V263, (32768 – m) writes for the SN74V273,
(65536 – m) writes for the SN74V283, and (131072 – m) writes for the SN74V293. Offset m is the full offset
value. The default setting for these values is in the footnote of Table 2. This parameter also is user
programmable (see the programmable-flag offset loading section).
When the FIFO is full, FF goes low, inhibiting further write operations. If no reads are performed after a reset,
FF goes low after D writes to the FIFO. If the ×18 input or ×18 output bus width is selected, D = 8192 writes for
the SN74V263, D = 16384 writes for the SN74V273, D = 32768 writes for the SN74V283, and D = 65536 writes
for the SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16384 writes for the SN74V263,
D = 32768 writes for the SN74V273, D = 65536 writes for the SN74V283, and D = 131072 writes for the
SN74V293.
If the FIFO is full, the first read operation causes FF to go high after two low-to-high transitions on WCLK.
Subsequent read operations cause PAF and HF to go high at the conditions shown in Table 3. If further read
operations occur without write operations, PAE goes low when there are n words in the FIFO, where n is the
empty offset value. Continuing read operations causes the FIFO to become empty . When the last word has been
read from the FIFO, EF goes low, inhibiting further read operations. REN is ignored when the FIFO is empty.
When configured in standard mode, the EF and FF outputs are double register-buffered outputs.
See Figures 7, 8, and 11 for timing diagrams for standard mode.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
20 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Table 2. Default Programmable Flag Offsets
OFFSETS (n, m)†OFFSETS (n, m)†
LD
FSEL0
FSEL1
SN74V263
LD
FSEL0
FSEL1
SN74V283
LD
FSEL0
FSEL1
SN74V263
SN74V273
LD
FSEL0
FSEL1
ALL OTHER
MODES ×9 TO ×9
MODE SN74V293
H L L 1,023 L L H 511 16383 16383
L L H 511 L H L 255 8191 8191
L H L 255 L H H 63 4,095 4,095
L L L 127 H L H 31 2,047 2,047
L H H 63 H L L 1,023 1,023 1,023
H L H 31 H H L 15 511 511
H H L 15 H H H 7 255 255
H H H 7 L L L 127 127 127
†n = empty offset for PAE, m = full of fset for PAF
programming flag offsets
Full and empty flag offset values are user programmable. The SN74V263, SN74V273, SN74V283, and
SN74V293 have internal registers for these offsets. Eight default offset values are selectable during master
reset. These offset values are shown in Table 2. Offset values also can be programmed into the FIFO by serial
or parallel loading. The loading method is selected using LD. During master reset, the state of the LD input
determines whether serial or parallel flag offset programming is enabled. A high on LD during master reset
selects serial loading of offset values. A low on LD during master reset selects parallel loading of of fset values.
In addition to loading offset values into the FIFO, it also is possible to read the current offset values. Offset values
can be read via the parallel output ports Q0–Qn, regardless of the programming mode selected (serial or
parallel). It is not possible to read the offset values in serial fashion.
Figure 3 summarizes the control pins and sequence for both serial and parallel programming modes. A more
detailed description is given in the following paragraphs.
The offset registers can be programmed (and reprogrammed) any time after master reset, regardless of whether
serial or parallel programming has been selected. Valid programming ranges are from 0 to D – 1.
synchronous vs asynchronous programmable-flag timing selection
The SN74V263, SN74V273, SN74V283, and SN74V293 can be configured during the master reset cycle with
either synchronous or asynchronous timing for PAF and PAE flags by use of the PFM pin.
If synchronous P AF/PAE configuration is selected (PFM high during MRS), P AF is asserted and updated on the
rising edge of WCLK only and not RCLK. Similarly, PAE is asserted and updated on the rising edge of RCLK
only and not WCLK (see Figure 18 for synchronous PAF timing and Figure 19 for synchronous PAE timing).
If asynchronous PAF/PAE configuration is selected (PFM low during MRS), PAF is asserted low on the
low-to-high transition of WCLK and PAF is reset to high on the low-to-high transition of RCLK. Similarly, PAE
is asserted low on the low-to-high transition of RCLK. P AE is reset to high on the low-to-high transition of WCLK
(see Figure 20 for asynchronous PAF timing and Figure 21 for asynchronous PAE timing).
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
21
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Table 3. Status Flags for Standard Mode
IW = OW = ×9 SN74V263 SN74V273 SN74V283 SN74V293
IW ≠ OW OR
IW = OW = ×18 SN74V263 SN74V273 SN74V283 SN74V293 FF PAF HF PAE EF
0 0 0 0 0 H H H L L
1 to n 1 to n 1 to n 1 to n 1 to n H H H L H
(n + 1) to 4096 (n + 1) to 8192 (n + 1) to 16384 (n + 1) to 32768 (n + 1) to 65536 H H H H H
Number of
Words
in FIFO
4097 to
[8192 – (m + 1)] 8193 to
[16384 – (m + 1)] 16385 to
[32768 – (m + 1)] 32769 to
[65536 – (m + 1)]
65537 to
[131072 –
(m + 1)] H H L H H
(8192 – m) to
8191 (16384 – m) to
16383 (32768 – m) to
32767 (65536 – m) to
65535 (131072 – m) to
131071 H L L H H
8192 16384 32768 65536 131072 L L L H H
NOTE 1: See Table 2 for values for n, m.
Table 4. Status Flags for FWFT Mode
IW = OW = ×9 SN74V263 SN74V273 SN74V283 SN74V293
IW ≠ OW OR
IW = OW = ×18 SN74V263 SN74V273 SN74V283 SN74V293 IR PAF HF PAE OR
0 0 0 0 0 L H H L H
1 to (n + 1) 1 to (n + 1) 1 to (n + 1) 1 to (n + 1) 1 to (n + 1) L H H L L
N mber of
(n + 2) to 4097 (n + 2) to 8193 (n + 2) to 16385 (n + 2) to 32769 (n + 2) to 65537 L H H H L
N
u
mber
of
Words
in FIF
O
4098 to
[8193 – (m + 1)] 8194 to
[16385 – (m + 1)] 16386 to
[32769 – (m + 1)] 32770 to
[65537 – (m + 1)] 65538 to
[131073 – (m + 1)] L H L H L
in
FIFO
(8193 – m) to
8192 (16385 – m) to
16384 (32769 – m) to
32768 (65537 – m) to
65536 (131073 – m) to
131072 L L L H L
8193 16385 32769 65537 131073 H L L H L
NOTES: 1. See Table 2 for values for n, m.
2. Number of words in FIFO = FIFO depth + output register
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
22 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
1st Parallel Offset Write/Read Cycle 1st Parallel Offset Write/Read Cycle
D/Q8 D/Q0 D/Q8 D/Q0
EMPTY OFFSET REGISTER EMPTY OFFSET REGISTER
X8765432 1 X8765432 1
2nd Parallel Offset Write/Read Cycle 2nd Parallel Offset Write/Read Cycle
D/Q8 D/Q0 D/Q8 D/Q0
EMPTY OFFSET REGISTER EMPTY OFFSET REGISTER
X 16 15 14 13 12 11 10 9 X 16 15 14 13 12 11 10 9
3rd Parallel Offset Write/Read Cycle 3rd Parallel Offset Write/Read Cycle
D/Q8 D/Q0 D/Q8 D/Q0
FULL OFFSET REGISTER EMPTY OFFSET REGISTER
X 8 7 6 5 4 3 2 1 X X X X X X X X 17
4th Parallel Offset Write/Read Cycle 4th Parallel Offset Write/Read Cycle
D/Q8 D/Q0 D/Q8 D/Q0
FULL OFFSET REGISTER FULL OFFSET REGISTER
X 16 15 14 13 12 11 10 9 X 8 7 6 5 4 3 2 1
SN74V263/SN74V273/SN74V283/SN74V293
×9 Bus Width (see Note A) 5th Parallel Offset Write/Read Cycle
D/Q8 D/Q0
X = don’t care FULL OFFSET REGISTER
X 16 15 14 13 12 11 10 9
6th Parallel Offset Write/Read Cycle
D/Q8 D/Q0
FULL OFFSET REGISTER
X X X X X X X X 17
SN74V293
×9 Bus Width (see Note A)
×9 TO ×9 MODE ALL OTHER MODES
Number of bits used:
14 bits for the SN74V263
15 bits for the SN74V273
16 bits for the SN74V283
17 bits for the SN74V293
Note: All unused bits of the
LSB and MSB are don’t care
Number of bits used:
13 bits for the SN74V263
14 bits for the SN74V273
15 bits for the SN74V283
16 bits for the SN74V293
Note: All unused bits of the
LSB and MSB are don’t care
NOTE A: When programming the SN74V293 with an input bus width of ×9 and output bus width of ×18, four write cycles are required. When
reading the SN74V293 with an output bus width of ×9 and input bus width of ×18, four read cycles are required. A total of six program/read
cycles are required for ×9 bus width if both the input and output bus widths are set to ×9.
Figure 3. Programmable Flag Offset Programming Sequence
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
23
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
1st Parallel Offset Write/Read Cycle
D/Q17 Data Inputs/Outputs D/Q0
EMPTY OFFSET REGISTER
XX 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 Noninterspersed Parity
16 15 14 13 12 11 10 9 X 8 7 6 5 4 3 2 1 Interspersed Parity
D/Q8 Number of Bits Used
2nd Parallel Offset Write/Read Cycle
D/Q17 Data Inputs/Outputs D/Q0
FULL OFFSET REGISTER
XX 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
16 15 14 13 12 11 10 9 X 8 7 6 5 4 3 2 1
D/Q8
SN74V263/SN74V273/SN74V283/SN74V293
×18 Bus Width
LD WEN REN SEN WCLK RCLK SN74V263, SN74V273, SN74V283, SN74V293
0 0 1 1 ↑X
Parallel write to registers:
Empty offset (LSB)
Empty offset (MSB)
Full offset (LSB)
Full offset (MSB)
0 1 0 1 X ↑
Parallel read from registers:
Empty offset (LSB)
Empty offset (MSB)
Full offset (LSB)
Full offset (MSB)
↑
×9 TO ×9 MODE ALL OTHER MODES
0 1 1 0
↑
X
Serial shift into registers:
28 bits for the SN74V263
30 bits for the SN74V273
32 bits for the SN74V283
34 bits for the SN74V293
1 bit for each rising WCLK edge,
starting with empty offset (LSB) and
ending with full offset (MSB)
Serial shift into registers:
26 bits for the SN74V263
28 bits for the SN74V273
30 bits for the SN74V283
32 bits for the SN74V293
1 bit for each rising WCLK edge,
starting with empty offset (LSB) and
ending with full offset (MSB)
X 1 1 1 X X No operation
1 0 X X ↑XWrite memory
1 X 0 X X ↑Read memory
1 1 1 X X X No operation
NOTES: B. The programming method can be selected only at master reset.
C. Parallel reading of the offset registers is always permitted, regardless of which programming method has been selected.
D. The programming sequence applies to FWFT and standard modes.
Figure 3. Programmable Flag Offset Programming Sequence (Continued)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
24 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
serial programming mode
If the serial programming mode has been selected as described previously, programming of PAE and PAF
values can be achieved by using a combination of the LD, SEN, WCLK, and SI inputs. Programming PAE and
PAF proceeds as follows; when LD and SEN are set low, data on the SI input are written, one bit for each WCLK
rising edge, starting with the empty offset LSB and ending with the full offset MSB. If ×9 to ×9 mode is selected,
a total of 28 bits for the SN74V263, 30 bits for the SN74V273, 32 bits for the SN74V283, and 34 bits for the
SN74V293. For any other mode of operation (including ×18 bus width on either the input or output), minus 2 bits
from the previous values. So, a total of 26 bits for the SN74V263, 28 bits for the SN74V273, 30 bits for the
SN74V283, and 32 bits for the SN74V293.
See Figure 15 for timing information.
Using the serial method, individual registers cannot be programmed selectively . P AE and P AF can show a valid
status only after the complete set of bits for all offset registers has been entered. The registers can be
reprogrammed as long as the complete set of new offset bits is entered. When LD is low and SEN is high, no
serial write to the registers can occur.
Write operations to the FIFO are allowed before and during the serial programming sequence. In this case, the
programming of all offset bits does not have to occur at once. A select number of bits can be written to the SI
input and then, by bringing LD and SEN high, data can be written to FIFO memory via Dn by toggling WEN.
When WEN is brought high with LD and SEN restored to a low, the next offset bit in sequence is written to the
registers via SI. If an interruption of serial programming is desired, it is sufficient either to set LD low and
deactivate SEN or to set SEN low and deactivate LD. Once LD and SEN are restored to a low level, serial offset
programming continues.
From the time serial programming has begun, neither programmable flag is valid until the full set of bits required
to fill all the offset registers is written. Measuring from the rising WCLK edge that achieves the previous criteria,
PAF is valid after two more rising WCLK edges + tPAF, PAE is valid after the next two rising
RCLK edges + tPAE + tsk2 in synchronous timing mode.
It is not possible to read the flag offset values in a serial mode.
parallel programming mode
If the parallel programming mode has been selected as described previously, programming of PAE and PAF
values can be achieved by using a combination of the LD, WCLK , WEN and Dn inputs. If the FIFO is configured
for an input bus width and output bus width both set to ×9, the total number of write operations required to
program the offset registers is four for the SN74V263, SN74V273, and SN74V283, or six for the SN74V293.
Refer to Figure 3 for a diagram of the data input lines D0–Dn used during parallel programming. If the FIFO is
configured for an input-to-output bus width of ×9 to ×18, ×18 to ×9, or ×18 to ×18, the following number of write
operations are required. For an input bus width of ×18, a total of two write operations is required to program the
offset registers for the SN74V263, SN74V273, SN74V283, and SN74V293. For an input bus width of ×9, a total
of four write operations is required to program the offset registers for the SN74V263, SN74V273, SN74V283,
and SN74V283 (see Figure 3).
For example, programming P AE and P AF on the SN74V293 configured for ×18 bus width proceeds as follows:
when LD and WEN are set low, data on inputs Dn are written into the LSB of the empty offset register on the
first low-to-high transition of WCLK. On the second low-to-high transition of WCLK, data are written into the MSB
of the empty offset register . On the third low-to-high transition of WCLK, data are written into the LSB of the full
offset register. On the fourth low-to-high transition of WCLK, data are written into the MSB of the full offset
register. On the fifth low-to-high transition of WCLK, data are written again to the empty offset register. Note that,
for ×9 bus width, one additional write cycle is required for the empty offset register and full offset register.
See Figure 16 for timing information.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
25
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
parallel programming mode (continued)
Writing offsets in parallel employs a dedicated write offset register pointer . Reading offsets employs a dedicated
read offset register pointer . The two pointers operate independently; however , a read and a write should not be
performed simultaneously to the offset registers. A master reset initializes both pointers to the empty offset
(LSB) register. A partial reset has no effect on the position of these pointers (see Figure 3 for a diagram of the
data input lines D0–Dn used during parallel programming).
Write operations to the FIFO are allowed before and during the parallel programming sequence. In this case,
the programming of all offset registers need not occur at one time. One, two, or more offset registers can be
written. Then, by bringing LD high, write operations can be redirected to the FIFO memory . When LD is set low
again and WEN is low, the next offset register in sequence is written to. As an alternative to holding WEN low
and switching LD, parallel programming also can be interrupted by setting LD low and switching WEN.
Note that the status of a programmable-flag (PAE or PAF) output is invalid during the programming process.
From the time parallel programming has begun, a programmable-flag output is not valid until the appropriate
offset word has been written to the register(s) pertaining to that flag. Measuring from the rising WCLK edge that
achieves the previous criteria, P AF is valid after two more rising WCLK edges + tPAF, and P AE is valid after the
next two rising RCLK edges + tPAE + tsk2 in synchronous timing mode.
Reading the offset registers employs a dedicated read offset register pointer. The contents of the offset registers
can be read on the Q0–Qn pins when LD is set low and REN is set low. If the FIFO is configured for both an
input bus width and output bus width set to ×9, the total number of read operations required to read the offset
registers is four for the SN74V263, SN74V273, and SN74V283, or six for the SN74V293 (see Figure 3 for a
diagram of the data input lines D0–Dn used during parallel programming). If the FIFO is configured for an
input-to-output bus width of ×9 to ×18, ×18 to ×9, or ×18 to ×18, the following number of read operations are
required. For an output bus width of ×18, a total of two read operations is required to read the offset registers
for the SN74V263, SN74V273, SN74V283, and SN74V293. For an output bus width of ×9, a total of four read
operations is required to read the offset registers for the SN74V263, SN74V273, SN74V283, and SN74V293
(see Figure 3 ). For example, reading PAE and PAF on the SN74V293 configured for ×18 bus width proceeds
as follows. Data are read via Qn from the empty offset register on the first and second low-to-high transition of
RCLK. On the third and fourth low-to-high transitions of RCLK, data are read from the full offset register. The
fifth and sixth transition of RCLK reads again from the empty offset register. Note that for a ×9 bus width, one
additional read cycle is required for both the empty offset register and full offset register.
See Figure 17 for timing information.
It is permissible to interrupt the offset register read sequence with reads or writes to the FIFO. The interruption
is accomplished by deasserting REN, LD, or both together. When REN and LD are restored to a low level,
reading of the offset registers continues where it left of f. It should be noted (and care should be taken from the
fact) that when a parallel read of the flag offsets is performed, the data word that was present on the output lines
Qn is overwritten.
Parallel reading of the offset registers always is permitted, regardless of which timing mode (FWFT or standard)
has been selected.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
26 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
retransmit operation
The retransmit operation allows data that has already been read to be accessed again. There are two modes
of retransmit operation: normal latency and zero latency. There are two stages to retransmit. The first stage is
a setup procedure that resets the read pointer to the first location of memory. The second stage is the actual
retransmit, which consists of reading out the memory contents, starting at the beginning of memory.
Retransmit setup is initiated by holding RT low during a rising RCLK edge. REN and WEN must be high before
RCLK goes high while R T is low. When zero latency is utilized, REN need not be high before bringing R T low.
At least two words, but no more than D – 2 words, should have been written into the FIFO and read from the
FIFO between reset (master or partial) and the time of retransmit setup. If ×18 input or ×8 output bus width is
selected, D = 8192 for the SN74V263, D = 16384 for the SN74V273, D = 32768 for the SN74V283, and
D = 65536 for the SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16384 for the
SN74V263, D = 32768 for the SN74V273, D = 65536 for the SN74V283, and D = 131072 for the SN74V293.
In FWFT mode, if ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the
SN74V273, D = 32769 for the SN74V283, and D = 65537 for the SN74V293. If both ×9 input and ×9 output bus
widths are selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283,
and D = 131073 for the SN74V293.
In normal retransmit mode, if FWFT mode is selected, the FIFO marks the beginning of the retransmit setup
by setting OR high. During this period, the internal read pointer is set to the first location of the RAM array.
When OR goes low , retransmit setup is complete. At the same time, contents of the first location appear on the
outputs. Since FWFT mode is selected, the first word appears on the outputs; no low on REN is necessary.
Reading all subsequent words requires a low on REN to enable the rising edge of RCLK.
See Figure 12 for timing information.
If standard mode is selected, the FIFO marks the beginning of the retransmit setup by setting EF low. The
change in level is noticeable only if EF was high before setup. During this period, the internal read pointer is
initialized to the first location of the RAM array.
When EF goes high, retransmit setup is complete and read operations can begin, starting with the first location
in memory. Since standard mode is selected, every word read, including the first word following retransmit
setup, requires a low on REN to enable the rising edge of RCLK.
See Figure 11 for timing information.
For either FWFT mode or standard mode, updating of the PAE, HF, and PAF flags begins with the rising edge
of RCLK that the RT is set up on. PAE is synchronized to RCLK, thus, on the second rising edge of RCLK after
RT is set up, the PAE flag is updated. HF is asynchronous, thus, the rising edge of RCLK that RT is set up on
updates HF . P AF is synchronized to WCLK, thus, the second rising edge of WCLK that occurs tsk after the rising
edge of RCLK that RT is set up on updates PAF. RT is synchronized to RCLK.
The retransmit function has the option of two modes of operation, either normal latency or zero latency.
Figures 1 1 and 12 show to normal latency . Figures 13 and 14 show the zero-latency retransmit operation. Zero
latency means, basically , that the first data word to be retransmitted is placed in the output register with respect
to the RCLK pulse that initiated the retransmit.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
27
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
BYTE ORDER ON INPUT PORT: D17–D9 D8–D0
ABWrite to FIFO
BYTE ORDER ON OUTPUT PORT: Q17–Q9 Q8–Q0
ABRead from FIFO
BE IW OW
L L L (a) ×18 INPUT TO ×18 OUTPUT – BIG ENDIAN
Q17–Q9 Q8–Q0
BARead from FIFO
BE IW OW
H L L (b) ×18 INPUT TO ×18 OUTPUT – LITTLE ENDIAN
Q17–Q9 Q8–Q0
XA1st: Read from FIFO
BE IW OW Q17–Q9 Q8–Q0
L L H X B 2nd: Read from FIFO
(c) ×18 INPUT TO ×9 OUTPUT – BIG ENDIAN
Q17–Q9 Q8–Q0
XB1st: Read from FIFO
BE IW OW Q17–Q9 Q8–Q0
H L H X A 2nd: Read from FIFO
(d) ×18 INPUT TO ×9 OUTPUT – LITTLE ENDIAN
BYTE ORDER ON INPUT PORT: D17–D9 D8–D0
XA1st: Write to FIFO
D17–D9 D8–D0
X B 2nd: Write to FIFO
BYTE ORDER ON OUTPUT PORT: Q17–Q9 Q8–Q0
ABRead from FIFO
BE IW OW
L H L (a) ×9 INPUT TO ×18 OUTPUT – BIG ENDIAN
Q17–Q9 Q8–Q0
BARead from FIFO
BE IW OW
H H L (a) ×9 INPUT TO ×18 OUTPUT – LITTLE ENDIAN
Figure 4. Bus-Matching Byte Arrangement
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
28 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
If FWFT = High, OR = High
If FWFT = Low , EF = Low
If FWFT = Low , FF = High
If FWFT = High, IR = Low
tRSS
tRSS
tRSS
tRSS
tRSS
tRSS
tRSS
tRSS
tRSS
tRSS
tRSS
tRSR
tRSS
MRS
REN
FWFT/SI
WEN
FSEL0,
FSEL1
RT
SEN
PAE
PAF, HF
EF/OR
FF/IR
OW, IW
BE
RM
PFM
IP
LD
Q0–Qn OE = High
OE = Low
tRSR
tRSR
tRSR
tRSF
tRSF
tRSF
tRSF
tRSF
Figure 5. Master Reset Timing
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
29
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
If FWFT = Low , EF = Low
tRSS
tRSS
tRSS
tRSS
tRS
PRS
REN
WEN
RT
SEN
PAE
PAF, HF
EF/OR
FF/IR
Q0–Qn
If FWFT = High, OR = High
If FWFT = Low , FF = High
If FWFT = High, IR = Low
OE = High
OE = Low
tRSR
tRSF
tRSR
tRSF
tRSF
tRSF
tRSF
Figure 6. Partial Reset Timing
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
30 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
tENS tENS
tDS
tWFF
tWFF
tWFF
Data Read Next Data ReadData In Output Register
tENH
tENH
tsk1
(see Note A)
tsk1
(see Note A)
tCLKH
WEN
RCLK
REN
WCLK
1212
Dx Dx + 1
FF
tDS
tWFF
tA
tA
Q0–Qn
D0–Dn
tDH
tDH
No Write tCLK tCLKH
No Write
NOTES: A. tsk1 is the minimum time between a rising RCLK edge and a rising WCLK edge to ensure that FF goes high (after one
WCLK cycle + tWFF). If the time between the rising edge of the RCLK and the rising edge of the WCLK is less than tsk1, the FF
deassertion can be delayed one additional WCLK cycle.
B. LD = high, EF = high
Figure 7. Write-Cycle and Full-Flag Timing (Standard Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
31
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
tDS
tOLZ
No Operation
RCLK
REN
EF
OE
WEN
12
No Operation
Last Word
tsk1
(see Note A)
tref
tOLZ
tOHZ
tENH
tENS
tDH
tENH
tENS
tDS tDH
Last Word
tENS tENH
tCLKH tCLKL
tENS tENH tENH
tA
tref
tA
tref
tA
tOE
WCLK
Q
0–Qn
D0–Dn D0 D1
D0 D1
tCLK
tENS
NOTES: A. tsk1 is the minimum time between a rising WCLK edge and a rising RCLK edge to ensure that EF goes high (after one
RCLK cycle + tref). If the time between the rising edge of WCLK and the rising edge of RCLK is less than tsk1, EF deassertion can
be delayed one additional RCLK cycle.
B. LD = high
C. First-data-word latency: tsk1 + 1*TRCLK + tREF
Figure 8. Read-Cycle, Empty-Flag, and First-Data-Word-Latency Timing (Standard Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 18, 16384 18, 32768 18, 65536 18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
×
×
×
×
32 POST OFFICE BOX 655303 DALLAS, TEXAS 75265
•
ÎÎ
ÎÎ
ÎÎ
ÎÎ
ÎÎ
ÎÎ
ÎÎ
ÎÎ
Î
Î
Î
Î
Î
Î
Î
Î
ÎÎ
ÎÎ
ÎÎ
ÎÎ
ÎÎ
ÎÎ
Î
Î
Î
Î
Î
Î
Î
Î
ÎÎÎ
ÎÎÎ
1 1
WCLK
D0–D17
tENS
WEN
tDH
tDS tDS
tDS tDS tENH
W1 W2 W3 W4 W[n+2] W[n+3] W[n+4] D – 1+ 1
W2D – 1+ 2
W2D – 1+ 3
W2W[D-m-2] W[D-m-1] W[D-m] W[D-m+2] W[D] W[D+1]
tsk1 (see Note A)
RCLK
REN
Q0–Q17
12 3
tA
Data in Output Register W1
tREF
OR
tsk2 (see Note B)
tPAES
PAE
tHF
HF
tPAFS
PAF
tWFF
IR
NOTES: A. tsk1 is the minimum time between a rising WCLK edge and a rising RCLK edge to ensure that OR goes low after two RCLK cycles + tREF. If the time between the rising
edge of WLCK and the rising edge of RCLK is less than tsk1, OR deassertion might be delayed one additional RCLK cycle.
B. tsk2 is the minimum time between a rising WCLK edge and a rising RCLK edge to ensure that PAE goes high after one RCLK cycle + tPAES. If the time between the
rising edge of WCLK and the rising edge of RCLK is less than tsk2, PAE deassertion might be delayed one additional RCLK cycle.
C. LD = high, OE = low
D. n = PAE offset, m = PAF offset, D = maximum FIFO depth
E. If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the SN74V273, D = 32769 for the SN74V283, and D = 65537 for the
SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283, and
D = 131073 for the SN74V293.
F. First-data-word latency: tsk1 + 2* TRCLK + tREF
12
2
Î
Î
Î
Î
W[D-m+1]
Figure 9. Write-Cycle and First-Data-Word-Latency Timing (FWFT Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 18, 16384 18, 32768 18, 65536 18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
×
×
×
×
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
•33
tOE
WCLK
ÎÎ
ÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ
WD
tENH
tENS
WEN
tsk1
(see Note A)
12
tDH
tDS
D0–D17
RCLK
tENS tENS
REN
OE
tOHZ tA
tAtAtAtAtA
tREF
Q0–Q17
tPAES
tHF
tPAFS
tWFF
tWFF
OR
PAE
HF
PAF
IR
W1 W1 W2 W3 W[m+3]Wm+2 W[m+4] D – 1+ 1
W2D – 1+ 2
W2W[D-n-1] W[D-n] W[D-n+2] W[D-1] WD
NOTES: A. tsk1 is the minimum time between a rising RCLK edge and a rising WCLK edge to ensure that IR goes low after one WCLK cycle + tWFF. If the time between the rising
edge of RLCK and the rising edge of WCLK is less than tsk1, IR assertion might be delayed an additional WCLK cycle.
B. tsk2 is the minimum time between a rising RCLK edge and a rising WCLK edge for PAF to go high after one WCLK cycle + tPAFS. If the time between the rising edge
of RCLK and the rising edge of WCLK is less than tsk2, PAF deassertion may be delayed an additional WCLK cycle.
C. LD = high
D. n = PAE offset, m = PAF offset, D = maximum FIFO depth
E. If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the SN74V273, D = 32769 for the SN74V283, and D = 65537 for the
SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283, and
D = 131073 for the SN74V293.
tsk2
(see Note B)
2
1
W[D-n+1]
Figure 10. Read Timing (First-Word Fall-Through Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
34 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
W2
(see
Note C)
WCLK
RCLK
REN
RT
EF
PAF
HF
PAE
12
12
WEN
tENS tENH tENS tENH
tAtAtA
tsk2
tENS tENH
tREF tREF
tPAES
tHF
tPAFS
Q0–Qn Wx Wx + 1
tRTS
tRTS
W1 (see Note C)
NOTES: A. Retransmit setup is complete after EF returns high; only then can a read operation begin.
B. OE = low
C. W1 = first word written to the FIFO after master reset, W2 = second word written to the FIFO after master reset
D. No more than (D – 2) words may be written to the FIFO between reset (master or partial) and retransmit setup. Therefore, FF is
high throughout the retransmit setup procedure.
If ×18 input or ×18 output bus width is selected, D = 8192 for the SN74V263, D = 16384 for the SN74V273, D = 32768 for the
SN74V283, and D = 65536 for the SN74V293.
If both ×9 input and ×9 output bus widths are selected, D = 16384 for the SN74V263, D = 32768 for the SN74V273, D = 65536
for the SN74V283, and D = 131072 for the SN74V293.
E. There must be at least two words written to and two words read from the FIFO before a retransmit operation can be invoked.
F. RM is set high during MRS.
Figure 11. Retransmit Timing (Standard Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
35
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
WCLK
RCLK
REN
RT
OR
PAF
HF
PAE
12
1 2
WEN
34
tENS
tENH
tRTS tENS tENH
tA
tA
tsk2
tENS tENH
tREF tREF
tPAES
tHF
Q0–Qn Wx Wx + 1 W4
tPAFS
tRTS
tAtA
W1 (see Note D) W2 (see Note D) W3 (see Note D)
NOTES: G. Retransmit setup is complete after OR returns low.
H. No more than (D – 2) words can be written to the FIFO between reset (master or partial) and retransmit setup. Therefore, IR is
low throughout the retransmit setup procedure.
If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the SN74V273, D = 32769 for the
SN74V283, and D = 65537 for the SN74V293
If both ×9 input and ×9 output bus widths are selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537
for the SN74V283, and D = 131073 for the SN74V293.
I. OE = low
J. W1, W2, W3 = first, second, and third words written to the FIFO after master reset
K. There must be at least two words written to the FIFO before a retransmit operation can be invoked.
L. RM is set high during MRS.
Figure 12. Retransmit Timing (FWFT Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
36 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
WCLK
RCLK
REN
RT
PAF
HF
PAE
12
12
WEN
3
tENS tENH
tAtAtAtAtA
tsk2
tRTS
tENS
tENH
tHF
tPAES
Q0–Qn Wx Wx + 1 W1 W4
EF
(
see Note A)
tPAFS
W3 (see Note C)
NOTES: A. If the FIFO is empty at the point of retransmit, EF is updated based on RCLK (retransmit clock cycle). Valid data also appears
on the output.
B. OE = low, enables data to be read on outputs Q0–Qn
C. W2 = second word written to the FIFO after master reset, W3 = third word written to the FIFO after master reset
D. No more than (D – 2) words may be written to the FIFO between reset (master or partial) and retransmit setup. Therefore, FF is
high throughout the retransmit setup procedure.
If ×18 input or ×18 output bus width is selected, D = 8192 for the SN74V263, D = 16384 for the SN74V273, D = 32768 for the
SN74V283, and D = 65536 for the SN74V293.
If both ×9 input and ×9 output bus widths are selected, D = 16384 for the SN74V263, D = 32768 for the SN74V273, D = 65536
for the SN74V283, and D = 131072 for the SN74V293.
E. There must be at least two words written to and read from the FIFO before a retransmit operation can be invoked.
F. RM is set low during MRS.
W2 (see Note C)
Figure 13. Zero-Latency Retransmit Timing (Standard Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
37
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
W1 W2 (see Note D) W3 (see Note D) W4 (see Note D)
WCLK
RCLK
REN
RT
OR
PAF
HF
PAE
12
12
WEN
45
3
tENS tENH
tsk2
tENS tENH
tHF
tPAES
tPAFS
Q0–Qn Wx Wx + 1 W5
tAtAtAtAtA
tRTS
NOTES: A. If the part is empty at the point of retransmit, OR is updated based on RCLK (retransmit clock cycle). V alid data also appears on
the output.
B. No more than (D – 2) words may be written to the FIFO between reset (master or partial) and retransmit setup. Therefore, IR is
low throughout the retransmit setup procedure.
If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the SN74V273, D = 32769 for the
SN74V283, and D = 65537 for the SN74V293.
If both ×9 input and ×9 output bus widths are selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537
for the SN74V283, and D = 131073 for the SN74V293.
C. OE = low
D. W1, W2, W3 = first, second, and third words written to the FIFO after master reset.
E. There must be at least two words written to the FIFO before a retransmit operation can be invoked.
F. RM is set low during MRS.
Figure 14. Zero-Latency Retransmit Timing (FWFT Mode)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
38 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
Bit x
(see Note A)
Bit 0Bit x
(see Note A)
WCLK
SEN
SI
LD
tENS tENH tENH
tLDH
tLDS tLDH
tDH
tDS
Empty Offset Full Offset
Bit 0
NOTES: A. ×9 to ×9 mode: x = 13 for the SN74V263, x = 14 for the SN74V273, x = 15 for the SN74V283, and x = 16 for the SN74V293
B. All other modes: x = 12 for the SN74V263, x = 13 for the SN74V273, x = 14 for the SN74V283, and x = 15 for the SN74V293
Figure 15. Serial Loading of Programmable Flag Registers (FWFT and Standard Modes)
WCLK
LD
WEN
PAE Offset (MSB) PAF Offset (LSB)PAE Offset (LSB) PAF Offset (MSB)
tCLK
tLDS tLDH
tENS
tDS tDH
tENH
tDS tDH
tDS tDH
tDS tDH
tLD
H
tENH
D0–D16
NOTE A: This diagram is based on programming the SN74V293 ×18 bus width. Add one additional cycle to both the P AE offset and P AF of fset
for ×9 bus width.
tCLKH tCLKL
Figure 16. Parallel Loading of Programmable Flag Registers (FWFT and Standard Modes)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
39
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
PAF Offset (MSB)
tLDS
RCLK
LD
REN
Data In Output Register PAE Offset (LSB) PAE Offset (MSB) PAF Offset (LSB)
tENH
tLDH tLDH
tENH
Q0–Q16
tCLKL
tCLK
tAtAtAtA
NOTES: A. OE = low
B. This diagram is based on programming the SN74V293 ×18 bus width. Add one additional cycle to both the PAE offset and PAF
offset for ×9 bus width.
tCLKH
tENS
Figure 17. Parallel Read of Programmable Flag Registers (FWFT and Standard Modes)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
40 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
tsk2
(see Note C)
D – (m + 1) Words in FIFO
(see N otes A and B) D – (m + 1)
Words in
FIFO
(see Notes
A and B)
WCLK
WEN
PAF
RCLK
REN
1212
tCLKL
tENS tENH
tPAFS tPAES
tENS tENH
D – m Words in FIF O
(see N otes A and B)
tCLKH
NOTES: A. m = PAF offset
B. D = maximum FIFO depth
In FWFT mode: If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the SN74V273,
D = 32769 for the SN74V283, and D = 65537 for the SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16385
for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283, and D = 131073 for the SN74V293.
In standard mode: If ×18 input or ×18 output bus width is selected, D = 8192 for the SN74V263, D = 16384 for the SN74V273,
D = 32768 for the SN74V283, and D = 65536 for the SN74V293. If both ×9 Input and ×9 output bus widths are selected, D = 16384
for the SN74V263, D = 32768 for the SN74V273, D = 65536 for the SN74V283, and D = 131072 for the SN74V293.
C. tsk2 is the minimum time between a rising RCLK edge and a rising WCLK edge to ensure that PAF goes high (after one WCLK
cycle + tPAFS). If the time between the rising edge of RCLK and the rising edge of WCLK is less than tsk2, the PAF deassertion
time may be delayed one additional WCLK cycle.
D. PAF is asserted and updated on the rising edge of WCLK only.
E. Select this mode by setting PFM high during master reset.
Figure 18. Synchronous Programmable Almost-Full Flag Timing (FWFT and Standard Modes)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
41
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
tCLKL
tENH
n Words in FIFO (see Note B)
n + 1 Wo rds in FIFO ( see Note C)
tsk2
(see Note D)
WCLK
WEN
RCLK 12 1 2
REN
tENS
tPAES
n Words in FIFO (see Note B)
n + 1 Wo rds in FIFO ( see Note C)
tPAES
tENS tENH
n Words in FIFO (see Note B)
n + 1 Wo rds in FIFO ( see Note C)
NOTES: A. n = PAE offset
B. For standard mode
C. For FWFT mode
D. tsk2 is the minimum time between a rising WCLK edge and a rising RCLK edge to ensure that PAE goes high (after one RCLK
cycle + tPAES). If the time between the rising edge of WCLK and the rising edge of RCLK is less than tsk2, the PAE deassertion
can be delayed one additional RCLK cycle.
E. PAE is asserted and updated on the rising edge of RCLK only.
F. Select this mode by setting PFM high during master reset.
PAE
tCLKH
Figure 19. Synchronous Programmable Almost-Empty Flag Timing (FWFT and Standard Modes)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
42 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
tENS
tENH
D – (m + 1) Words in FIFO
D – m Words in FIF O
WCLK
WEN
PAF
RCLK
REN
tCLKH
tENS
tPAFA
tPAFA
D – (m + 1) Words in FIFO
tCLKL
NOTES: A. m = PAF offset
B. D = maximum FIFO depth
In FWFT mode: If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263, D = 16385 for the SN74V273,
D = 32769 for the SN74V283, and D = 65537 for the SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16385
for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283, and D = 131073 for the SN74V293.
In standard mode: If ×18 input or ×18 output bus width is selected, D = 8192 for the SN74V263, D = 16384 for the SN74V273,
D = 32768 for the SN74V283, and D = 65536 for the SN74V293. If both ×9 input and ×9 output bus widths are selected, D = 16384
for the SN74V263, D = 32768 for the SN74V273, D = 65536 for the SN74V283, and D = 131072 for the SN74V293.
C. PAF is asserted to low on WCLK transition and reset to high on RCLK transition.
D. Select this mode by setting PFM low during master reset.
Figure 20. Asynchronous Programmable Almost-Full Flag Timing (FWFT and Standard Modes)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
43
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
n + 1 Wo r ds in FIFO
(see Note B)
n + 2 Wo rds in FIF O
(see Note C)
n Words in FIFO
(see Note B)
n + 1 Words in FIFO
(see Note C)
WCLK
WEN
PAE
RCLK
REN
tCLKL
tENS tENH
tPAEA
n Words in FIFO (see Note B)
n+1 Words in FIFO (see Note C)
tENS
tPAEA
NOTES: A. n = PAE offset
B. For standard mode
C. For FWFT mode
D. PAE is asserted low on RCLK transition and reset to high on WCLK transition.
E. Select this mode by setting PFM low during master reset.
tCLKH
Figure 21. Asynchronous Programmable Almost-Empty Flag Timing (FWFT and Standard Modes)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
44 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
+ 1 Words in FIFO (see Note B)
WCLK
WEN
HF
RCLK
REN
D + 1
2
D/2 Words in FIFO (see Note A)
tENH
tENS
tENS
Words in FIFO (see Note B)
D
2+ 1 Words in FIFO (see Note A)
D + 1
2
D/2 Words in FIFO (see Note A)
Words in FIFO (see Note B)
D + 1
2
tCLKL
tCLKH
tHF
NOTES: A. In standard mode: D = maximum FIFO depth. If ×18 input or ×18 output bus width is selected, D = 8192 for the SN74V263,
D = 16384 for the SN74V273, D = 32768 for the SN74V283, and D = 65536 for the SN74V293. If both ×9 input and ×9 output bus
widths are selected, D = 16384 for the SN74V263, D = 32768 for the SN74V273, D = 65536 for the SN74V283, and D = 131072
for the SN74V293.
B. In FWFT mode: D = maximum FIFO depth. If ×18 input or ×18 output bus width is selected, D = 8193 for the SN74V263,
D = 16385 for the SN74V273, D = 32769 for the SN74V283, and D = 65537 for the SN74V293. If both ×9 input and ×9 output bus
widths are selected, D = 16385 for the SN74V263, D = 32769 for the SN74V273, D = 65537 for the SN74V283, and D = 131073
for the SN74V293.
tHF
Figure 22. Half-Full Flag Timing (FWFT and Standard Modes)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
45
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
optional configurations
width expansion configuration
Word width can be increased by connecting the control signals of multiple devices. Status flags can be detected
from any one device. The exceptions are the the IR and OR functions in FWFT mode and EF and FF functions
in standard mode. Because of variations in skew between RCLK and WCLK, it is possible for EF/FF deassertion
and IR/OR assertion to vary by one cycle between FIFOs. In standard mode, such problems can be avoided
by creating composite flags, that is, ANDing EF of every FIFO and separately ANDing FF of every FIFO. In
FWFT mode, composite flags can be created by ORing OR of every FIFO and separately ORing IR of every
FIFO.
Figure 23 demonstrates a width expansion using two SN74V263, SN74V273, SN74V283, and SN74V293
devices. If ×18 input or ×18 output bus width is selected, D0–D17 from each device form a 36-bit-wide input bus,
and Q0–Q17 from each device form a 36-bit-wide output bus. If both ×9 input and ×9 output bus widths are
selected, D0–D8 from each device form an 18-bit-wide input bus, and Q0–Q8 from each device form an
18-bit-wide output bus. Any word width can be attained by adding additional SN74V263, SN74V273,
SN74V283, and SN74V293 devices.
Read Clock (RCLK)
Read Enable (REN)
Output Enable (OE)
Write Clock (WCLK)
Retransmit (RT)
Half-Full Flag (HF)
Write Enable (WEN)
Load (LD)
First-Word Fall-Through or Serial Input
(FWFT/SI)
Programmable
Almost-Full Flag (PAF)
Data In
Partial Reset (PRS)
Master Reset (MRS)
m + n
Full Flag/Input Ready 2
(FF/IR)
Full Flag/Input Ready 1
(FF/IR)
Empty Flag/Output Ready 2
(EF/OR)
D0–Dm
m
(Dm + 1) – Dn
n
Q0–Qm
mn
(Qm + 1) – Qn
m + n Data Out
SN74V263
SN74V273
SN74V283
SN74V293
SN74V263
SN74V273
SN74V283
SN74V293
Programmable (PAE)
Empty Flag/Output Ready 1
(EF/OR)
Gate
Gate
NOTES: A. Use an OR gate in FWFT mode and an AND gate in standard mode.
B. Do not connect any output control signals together directly.
C. FIFO 1 and FIFO 2 must be the same depth, but can be different word widths.
(see Note A)
(see Note A)
FIFO 1 FIFO 2
Figure 23. Width-Expansion Block Diagam
(For the ×18 Input or ×18 Output Bus Width: 8192 × 36, 16384 × 36, 32768 × 36, and 65536 × 36)
(For Both ×9 Input and ×9 Output Bus Widths: 16284 × 18, 32768 × 18, 65536 × 18, and 131072 × 18)
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
46 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
depth-expansion configuration (FWFT mode only)
The SN74V263 can be adapted easily to applications requiring depths greater than 8192 when the ×18 input
or ×18 output bus width is selected, 16384 for the SN74V273, 32768 for the SN74V283, and 65536 for the
SN74V293. When both ×9 input and ×9 output bus widths are selected, depths greater than 16384 can be
adapted for the SN74V263, 32768 for the SN74V273, 65536 for the SN74V283, and 131072 for the SN74V293.
In FWFT mode, the FIFOs can be connected in series (the data outputs of one FIFO connected to the data inputs
of the next), with no external logic necessary. The resulting configuration provides a total depth equivalent to
the sum of the dpths associated with each single FIFO. Figure 24 shows a depth expansion using two
SN74V263, SN74V273, SN74V283, and SN74V293 devices.
Care should be taken to select FWFT mode during master reset for all FIFOs in the depth-expansion
configuration. The first word written to an empty configuration passes from one FIFO to the next (ripple down)
until it finally appears at the outputs of the last FIFO in the chain. No read operation is necessary , but the RCLK
of each FIFO must be free running. Each time the data word appears at the outputs of one FIFO, that device’s
OR line goes low, enabling a write to the next FIFO in line.
REN
Data In
Write Enable
Write Clock
SN74V263
SN74V273
SN74V283
SN74V293
FWFT/SI
Transfer Clock
WCLK
WEN
IR
Dn
RCLK
OR
REN
OE
Qn
WCLK
WEN
IR
Dn
RCLK
OR
OE
Qn
Read Clock
Read Enable
Input Ready Output Ready
Output Enable
Data Out
GND
nnn
SN74V263
SN74V273
SN74V283
SN74V293
FWFT/SI FWFT/SI
Figure 24. Depth-Expansion Block Diagram
(For the ×18 Input or ×18 Output Bus Width: 16384 × 18, 32768 × 18, 65536 × 18, and 131072 × 18)
(For Both ×9 Input and ×9 Output Bus Width: 32768 × 9, 65536 × 9, 131072 × 9, and 262144 × 9)
For an empty expansion configuration, the amount of time it takes for OR of the last FIFO in the chain to go low
(i.e., valid data to appear on the last FIFO’s outputs) after a word has been written to the first FIFO is the sum
of the delays for each FIFO:
(N – 1) ×(4 ×transfer clock) + 3 ×TRCLK
where N is the number of FIFOs in the expansion and TRCLK is the RCLK period. Note that extra cycles should
be added for the possibility that the tsk1 specification is not met between WCLK and transfer clock, or RCLK and
transfer clock, for the OR flag.
The ripple-down delay is noticeable only for the first word written to an empty depth-expansion configuration.
There is no delay evident for subsequent words written to the configuration.
The first free location created by reading from a full-depth-expansion configuration bubbles up from the last
FIFO to the previous one until it finally moves into the first FIFO of the chain. Each time a free location is created
in one FIFO of the chain, that FIFO’s IR line goes low, enabling the preceding FIFO to write a word to fill it.
For a full-expansion configuration, the amount of time it takes for IR of the first FIFO in the chain to go low after
a word has been read from the last FIFO is the sum of the delays for each individual FIFO:
(N – 1) ×(3 ×transfer clock) + 2TWCLK
where N is the number of FIFOs in the expansion and TWCLK is the WCLK period. Note that additional cycles
should be added for the possibility that the tsk1 specification is not met between RCLK and transfer clock, or
WCLK and transfer clock, for the IR flag.
SN74V263, SN74V273, SN74V283, SN74V293
8192 ×18, 16384 ×18, 32768 ×18, 65536 ×18
3.3-V CMOS FIRST-IN, FIRST-OUT MEMORIES
SCAS669D – JUNE 2001 – REVISED FEBRUARY 2003
47
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
depth-expansion configuration (FWFT mode only) (continued)
The transfer clock line should be tied to either WCLK or RCLK, whichever is faster. Both these actions result
in data moving as quickly as possible to the end of the chain and free locations moving to the beginning of the
chain.
PACKAGING INFORMATION
Orderable Device Status (1) Package
Type Package
Drawing Pins Package
Qty Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
SN74V263-10PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V263-15PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V263-6GGM ACTIVE BGA MI
CROSTA
R
GGM 100 184 TBD SNPB Level-3-220C-168 HR
SN74V263-6PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V263-7PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V273-10PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V273-15PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V273-6PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V273-7PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V283-10PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V283-15PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V283-6PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V283-7PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V293-10PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V293-15PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V293-15PZAG4 ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V293-6GGM ACTIVE BGA MI
CROSTA
R
GGM 100 184 TBD SNPB Level-3-220C-168 HR
SN74V293-6PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
SN74V293-7PZA ACTIVE LQFP PZA 80 90 Green (RoHS &
no Sb/Br) CU NIPDAU Level-4-260C-72 HR
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
PACKAGE OPTION ADDENDUM
www.ti.com 28-May-2009
Addendum-Page 1
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
OTHER QUALIFIED VERSIONS OF SN74V263, SN74V273, SN74V283, SN74V293 :
•Enhanced Product: SN74V263-EP,SN74V273-EP,SN74V283-EP,SN74V293-EP
NOTE: Qualified Version Definitions:
•Enhanced Product - Supports Defense, Aerospace and Medical Applications
PACKAGE OPTION ADDENDUM
www.ti.com 28-May-2009
Addendum-Page 2
MECHANICAL DATA
MPBG028B FEBRUAR Y 1997 – REVISED MAY 2002
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
GGM (S–PBGA–N100) PLASTIC BALL GRID ARRAY
0,08 0,10
1,40 MAX
0,85
0,55
0,45 0,45
0,35
0,95
4
C
B
A
D
E
213
K
F
G
H
J
576 9810
Seating Plane
SQ
9,90
10,10 7,20 TYP
0,40
0,40
A1 Corner
Bottom View
4145257–3/C 12/01
0,80
0,80
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice
C. MicroStar BGA configuration.
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