GS8128218/36(GB/GD)-xxxV

Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.

Rev: 1.01 5/2017

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© 2015, GSI Technology

Sleep Mode

During normal operation, ZZ must be pulled low, either by the user or by its internal pull down resistor. When ZZ is pulled high,

the SRAM will enter a Power Sleep mode after 2 cycles. At this time, internal state of the SRAM is preserved. When ZZ returns to

low, the SRAM operates normally after ZZ recovery time.

Sleep mode is dictated by the length of time the ZZ is in a High state. After entering Sleep mode, all inputs except ZZ become

disabled and all outputs go to High-Z The ZZ pin is an asynchronous, active high input that causes the device to enter Sleep mode.

operations or operations in progress may not be properly completed if ZZ is asserted. Therefore, Sleep mode must not be initiated

until valid pending operations are completed. Similarly, when exiting Sleep mode during tZZR, only a Deselect or Read commands

may be applied while the SRAM is recovering from Sleep mode.

Sleep Mode Timing

tZZR

tZZH

tZZS

Hold

Setup

tKL

tKL

tKH

tKH

tKC

tKC

CK

ADSP

ADSC

ZZ

Application Tips

Single and Dual Cycle Deselect

SCD devices (like this one) force the use of “dummy read cycles” (read cycles that are launched normally, but that are ended with

the output drivers inactive) in a fully synchronous environment. Dummy read cycles waste performance, but their use usually

assures there will be no bus contention in transitions from reads to writes or between banks of RAMs. DCD SRAMs do not waste

bandwidth on dummy cycles and are logically simpler to manage in a multiple bank application (wait states need not be inserted at

bank address boundary crossings), but greater care must be exercised to avoid excessive bus contention.

JTAG Port Operation

Overview

The JTAG Port on this RAM operates in a manner that is compliant with IEEE Standard 1149.1-1990, a serial boundary scan

Disabling the JTAG Port

It is possible to use this device without utilizing the JTAG port. The port is reset at power-up and will remain inactive unless

clocked. TCK, TDI, and TMS are designed with internal pull-up circuits.To assure normal operation of the RAM with the JTAG