GS881E18T GSI [GSI Technology], GS881E18T Datasheet - Page 23

• Manufacturer Part Number: GS881E18T
• Description: 512K x 18, 256K x 36 ByteSafe 8Mb Sync Burst SRAMs
• Manufacturer: GSI [GSI Technology]

Preliminary
GS881E18/36T-11/11.5/100/80/66
Sleep Mode Timing Diagram
CK
tH
tS
tKC
tKH tKL
ADSP
ADSC
tZZH
tZZS
tZZR
ZZ
Snooze
Application Tips
Single and Dual Cycle Deselect
SCD devices 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 consistent with IEEE Standard 1149.1-1990, a serial boundary scan interface
standard (commonly referred to as JTAG), but does not implement all of the functions required for 1149.1 compliance. Some
functions have been modified or eliminated because they can slow the RAM. Nevertheless, the RAM supports 1149.1-1990 TAP
(Test Access Port) Controller architecture, and can be expected to function in a manner that does not conflict with the operation of
Standard 1149.1 compliant devices. The JTAG Port interfaces with conventional TTL / CMOS logic level signaling.
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
Port unused, TCK, TDI, and TMS may be left floating or tied to either V
or V
. TDO should be left unconnected.
DD
SS
Rev: 1.10 9/2000
23/34
© 2000, Giga Semiconductor, Inc.
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.