Asynchronous, Cascadable 8K/16K/32K/64K x9 FIFOs
CY7C460A/CY7C462A
CY7C464A/CY7C466A
Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600
October 4, 1999
Features
• High-speed, low-power, first-in fir st- out (FIFO)
memories
• 8K x 9 FIFO (CY7C460A)
• 16K x 9 FIFO (CY7C462A)
• 32K x 9 FIFO (CY7C464A)
• 64K x 9 FIFO (CY7C466A)
• 10 -ns access time s, 20-ns rea d/write cycle times
• High-speed 50-MHz read/write independent of
depth/width
• Low op er ati n g pow e r
—ICC= 60 mA
—ISB =8 mA
• Asy nchronous read/write
• Empty and Full flags
• Half Full flag (in standalone mode)
• Retransmit (in standalone m ode)
• TTL-compatible
• Width and Depth Expansion Capability
•5V ± 10% supply
• PLCC, LCC, 300-mil and 600-mil DIP packag ing
• Three-state outputs
• Pin compatible density upgrade to CY7C42X/46X famil y
• Pin compatible and functionall y equival ent to IDT7205,
IDT7206, IDT7 207, IDT7208
Functional Descri pti on
The CY7C460A, CY7 C462A, CY7C4 64A, and CY7C46 6A ar e
respect ively, 8K, 16K , 32K, and 64K wo rds by 9- bit wide fir st-in
first-out (FIFO) memories. Each FIFO memory is organized
such that the data is read in the same sequential order that it
was written . Full and Empty fl ags are provided to prev ent ov er-
run and underrun. Three additi onal pins are also provided to
facilitate unlimited expansion in width, depth, or both. The
depth e xpansion technique steer s the control si gnals from one
device to another by passing tokens.
The read and write operations may be asynchronous; each
can occur at a rate of up to 50 MHz. The writ e operati on occurs
when the Write (W) signal is LOW. Read occurs when Read
(R) goes LOW. The nine data outputs go to the high-imped-
ance state when R is HI G H .
A Half Full (HF) out put fla g is pro vided th at is v alid in the stan-
dalone (single devi ce) and width expansion configurations. In
the depth expansion configuration, this pin provides the expan-
sion out (XO) in f ormatio n that is us ed t o tell th e ne xt FI FO tha t
it will be activated.
In the standalone and width expansion configurations , a LOW
on the Retransmit (RT) input causes the FIFOs to retransmit
the dat a. Read Enab l e (R) a nd Write Ena b le (W) mu st bot h be
HIGH during a retransmit cycle, and then R is used to access
the data.
The CY7C460A, CY7 C462A, CY7C4 64A, and CY7C46 6A ar e
fa bricate d using Cy pre ss’s adv anced 0.5µ RAM3 CMOS tech -
nology. Input ESD protection is greater than 2000V and
latch-up is prevented by careful layout and the use of guard
rings.
32K x
LogicBlockDiagram Pin Configurations
1
2
3
4
5
6
7
8
9
10
11
12
15
16
17
18
19
20
24
23
22
21
13
14
25
28
27
26
Top View
DIP
W
D8
D3
D2
D1
D0
XI
FF
Q0
Q1
Q2
GND
VCC
D4
FL/RT
MR
EF
XO/HF
Q7
R
PLCC/LCC
Top View
Q3
Q8
D5
D6
D7
Q6
Q5
Q4
4 3 2 1 32 31 30
14 15 16 17 18 19 20
5
6
7
8
9
10
11
12
13
29
28
27
26
25
24
23
22
21
FL/RT
MR
EF
XO/HF
Q7
D6
Q6
D7
NC
READ
CONTROL
WRITE
CONTROL
WRITE
POINTER
RESET
LOGIC
EXPANSION
LOGIC
RAM ARRAY
8K x 9
16K x 9
9
DATAINPUTS
(D0−D8)
THREE–
STATE
BUFFERS
DATAOUTPUTS
(Q0-Q 8)
W
READ
POINTER
FLAG
LOGIC
R
XI
EF
FF
XO/HF
MR
FL/RT
D2
D1
D0
XI
FF
Q0
Q1
NC
Q2
D
D
W
NC
V
D
D
3
8
cc
4
5
Q
Q
GND
NC
R
Q
Q
3
8
4
5
C46XA–1
C46XA–2
C46XA–3
7C460A
7C462A
7C464A
7C460A
7C462A
7C464A
64K x 9
7C466A 7C466A
DUAL PORT