IS61QDPB24M18A Datasheet, PDF (4/31 Pages) Integrated Silicon Solution, Inc – Fixed 2-bit burst for read and write operations

IS61QDPB24M18A/A1/A2
IS61QDPB22M36A/A1/A2
SRAM Features description
Block Diagram
36 (18)
D (Data-In)
Data
Register
20 (21)
Address
Address
Register
19 (20)
R#
W#
BWx#
4 (2)
Control
Logic
72 (36) 72 (36)
Write
Driver
72 (36)
2M x 36
(4M x 18)
Memory Array
72 (36)
72 (36)
Output
Register
72(36)
36 (18)
36 (18)
Q (Data-out)
QVLD
2
QVLD
2
CQ, CQ#
CQ, CQ#
(Echo Clocks) (Echo Clocks)
K
K#
Doff#
Clock
Generator
Select Output Control
Note: Numerical values in parentheses refer to the x18 device configuration.
Read Operations
The SRAM operates continuously in a burst-of-two mode. Read cycles are started by registering R# in active low state
at the rising edge of the K clock. R# can be activated every other cycle because two full cycles are required to
complete the burst of two in DDR mode. A set of free-running echo clocks, CQ and CQ#, are produced internally with
timings identical to the data-outs. The echo clocks can be used as data capture clocks by the receiver device.
The data corresponding to the first address is clocked two and half cycles later by the rising edge of the K# clock. The
data corresponding to the second burst is clocked three cycles later by the following rising edge of the K clock.
A NOP operation (R# is high) does not terminate the previous read.
Write Operations
Write operations can also be initiated at every rising edge of the K clock with first data whenever W# is low. The write
address is provided half cycle with second data later, registered by the rising edge of K#, so the write always occurs in
bursts of two.
The write data is provided in an ‘early write’ mode; that is, the data-in corresponding to the first address of the burst, is
presented half cycle before the rising edge of the following K clock. The data-in corresponding to the second write
burst address follows next, registered by the rising edge of K#.
Integrated Silicon Solution, Inc.- www.issi.com
4
Rev. C
08/21/2014