AS9C25256M2036L
AS9C25128M2036L
9/30/04, v.1.3 Alliance Semiconductor P. 7 of 30
®
Signal description
Notes:
1. Subscript 'x' represents 'A' for Port A and 'B' for Port B.
2. OPTx,VDDQx and VDD must be set to appropriate operating levels before applying inputs on the I/Os and controls for that port.
3. OPTx = VDD (2.5V) implies that corresponding port's I/Os, addresses, clock, and controls will operate at 3.3V level and VDDQx must be supplied at 3.3V.
OPTx = VSS (0V) implies that corresponding port's I/Os, addresses, clock, and controls will operate at 2.5V level and VDDQx must be supplied at 2.5V.
Each port can independently operate on either of the VDDQ levels.
4. If unused JTAG inputs may be left unconnected.
5. JTAG is not supported in PQFP package.
6. Address A17 is a NC forAS9C25128M2036L
Signal
I/O Properties Description NotesPort A Port B
CLKA CLKB ICLOCK
Clock. Each port has an independent Clock input that can be of different frequencies.
All inputs except OEx and ZZx are synchronous to the corresponding port’s clock and
must meet setup and hold time about the rising edge of the clock.
1
A0A - A17A A0B - A17B I SYNC External Address. Sampled on the rising edge of corresponding port clock 6
DQ0A - DQ35ADQ0B - DQ35B I/O SYNC Bidirectional data pins
CE0A, CE1A CE0B, CE1B I SYNC Chip enable inputs. Active low and high, respectively. Sampled on the rising edge of
corresponding port clock.
R/WAR/WB I SYNC Read/Write enable. Drive this pin LOW to write to, or HIGH to Read from the
memory array.
BE0A - BE3A BE0B - BE3BI SYNC
Byte Enable Inputs. Active low. Asserting these signals enables Read and Write
operations to the corresponding bytes of the memory array. (Refer Byte Control
Truth Table)
ADSAADSB I SYNC Address Strobe Enable.Active low. Loads external address onto the counter. (Refer
Counter Control Truth Table)
INCAINCB I SYNC Address Counter Increment. Active low. Increments the counter value. (Refer
Counter Control Truth Table)
RPTARPTB I SYNC Address Counter Repeat. Active low. Reloads the counter with the previously loaded
external address.(Refer Counter Control Truth Table)
OEAOEB I ASYNC Asynchronous output enable. I/O pins are driven when the OE is low and the chip is
in Read mode. A high on OE tristates the I/O pins.
ZZAZZB I ASYNC Snooze Mode Input. Places the device in low power mode. Data is retained. This pin
has an internal pull-down and can be floating.
PL/FTAPL/FTB ISTATIC
Pipeline/Flow-Through Select. When low, enables single register flow-through
mode. When high, enables double register Pipeline mode. This pin has an internal
pull-up and can be left floating to operate in pipeline mode.
OPTAOPTB ISTATIC
VDDQx Option. OPTx selects the operating voltage levels for the I/Os, addresses,
clock, and controls on that port. This pin has an internal pull-up and can be left
floating to operate in 3.3V mode.
1,2,3
INTAINTB O SYNC Interrupt Flag. Used for message passing between two ports. (Refer Interrupt Logic
Truth Table)
COLACOLB O SYNC Collision Alert Flag. Used to indicate collision during simultaneous memory access
to the same location by both the ports (Refer Collision Detection Truth Table)
VDDQAVDDQB IPOWER
Power to I/O bus. Can be 3.3V or 2.5V depending on OPTx input. 1,2,3
VDD I POWER Power Inputs (To be connected to 2.5V Power supply) 2
VSS I GROUND Ground Inputs (To be connected to Ground supply)
TCK I CLOCK
(JTAG) JTAG Test Clock Input. All JTAG signals except TRST are synchronous to this clock. 4,5
TDI I SYNC
(JTAG)
JTAG Test Data Input. Data on the TDI input will be shifted serially into selected
registers. 4,5
TDO O SYNC
(JTAG)
JTAG Test Data Output. TDO transitions occur on the falling edge of TCK. TDO is
normally tristated except when the captured data is shifted out of the JTAG TAP. 5
TMS I SYNC
(JTAG)
JTAG Test Mode Select Input. It controls the JTAG TAP state machine. State
machine transitions occur on the rising edge of TCK. 4,5
TRST I
ASYNC
(JTAG) JTAG Test Reset Input. Asynchronous input used to initialize TAP controller. 4,5