256K X 36, 512K X 18
3.3V Synchronous ZBT
TM
SRAMs
3.3V I/O, Burst Counter
Flow-Through Outputs
AS8C803625A
AS8C801825A
Features
256K x 36, 512K x 18 memory configuration
Supports high performance system speed –
100MHz (7.5ns Clock-To-Data Access)
ZBT
TM
Feature – No dead cycles between write
and read cycles
Internally synchronized output buffer enable
eliminates the need to control OE
Single R/W (READ/WRITE) control pin
4-word burst capability (Interleaved or linear)
Individual byte write (BW
1
– BW
4
) control
(May tie active)
Three chip enables for simple depth expansion
3.3V power supply (±5%)
3.3V (±5%) I/O Supply (V
DDQ
)
Power down controlled by ZZ input
Packaged in a JEDEC standard 100-pin plastic
thin quad flatpack (TQFP)
in and control signal registers. The outputs are
flow-through (no output data register). Output
enable is the only asynchronous signal and can be
used to disable the outputs at any given time.
A clock Enable (CEN) pin allows operation of
the 803625A/801825A to be suspended as long
as necessary. All synchronous inputs are ignored
when CEN is high and the internal device
registers will hold their previous values.
There are three chip enable pins (CE1, CE2,
CE2) that allow the user to deselect the device
when desired. If any one of these three is not
asserted when ADV/LD is low, no new memory
operation can be initiated. However, any pending
data transfers (reads or writes) will be
completed. The data bus will tri-state one cycle
after the chip is deselected or a write is initiated.
The 803625A/801825A have an on-chip burst
counter.
In the burst mode, the 803625A /
801825A can provide four cycles of data for a
single address presented to the SRAM. The order
of the burst sequence is defined by the LBO input
pin.
The LBO pin selects between linear and
interleaved burst sequence. The ADV/LD signal is
used
to
load
a
new
external
address
(ADV/LD=LOW) or increment the internal burst
counter (ADV/LD=HIGH).
The
803625A/801825A
SRAMs
utilize
Alliance’s latest high-performance CMOS process
and are packaged in a JEDEC Standard 14mm x
20mm 100-pin plastic thin quad flatpack (TQFP).
Description
The 803625A/801825A are 3.3V high-speed
9,437,184-bit (9 Megabit) synchronous SRAMs
organized as 256K x 36/512K x 18. They are
designed to eliminate dead bus cycles when
turning the bus around between reads and writes,
or writes and reads. Thus they have been given
the name ZBT
TM
, or Zero Bus Turnaround.
Address and control signals are applied to the
SRAM during one clock cycle, and on the next
clock cycle the associated data cycle occurs, be it
read or write.
The 803625A/801825A contain address, data-
Pin Description Summary
A
0
– A
18
CE
1
, CE
2
, CE
2
OE
R
/W
CEN
BW
1
, BW
2
, BW
3
, BW
4
CLK
ADV/LD
LBO
ZZ
I/O
0
– I/O
31
, I/O
P1
– I/O
P4
V
DD
, V
DDQ
V
SS
Address Inputs
Chip Enables
Output Enable
Read/Write Signal
Clock Enable
Individual Byte Write Selects
Clock
Advance Burst Address/Load New Address
Linear / Interleaved Burst Order
Sleep Mode
Data Input / Output
Core Power, I/O Power
Ground
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
I/O
Supply
Supply
Synchronous
Synchronous
Asynchronous
Synchronous
Synchronous
Synchronous
N/A
Synchronous
Static
Asynchronous
Synchronous
Static
Static
5298 tbl 01
NOVEMBER 2010
Talking
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