Features

• FT pin for user-configurable flow through or pipeline operation

• Dual Cycle Deselect (DCD) operation

• IEEE 1149.1 JTAG-compatible Boundary Scan

• 2.5 V or 3.3 V +10%/–10% core power supply

• 2.5 V or 3.3 V I/O supply

• LBO pin for Linear or Interleaved Burst mode

• Internal input resistors on mode pins allow floating mode pins

• Default to Interleaved Pipeline mode

• Byte Write (BW) and/or Global Write (GW) operation

• Internal self-timed write cycle

• Automatic power-down for portable applications

• JEDEC-standard 165-bump BGA package

• RoHS-compliant 100-pin TQFP and 165-bump BGA available

Functional Description

Applications

The GS8161E18D(GT/D)/GS8161E32D(D)/GS8161D36D(GT/D) is

an 18,874,368-bit high performance synchronous SRAM with

a 2-bit burst address counter. Although of a type originally

developed for Level 2 Cache applications supporting high

performance CPUs, the device now finds application in

synchronous SRAM applications, ranging from DSP main

store to networking chip set support.

Controls

Addresses, data I/Os, chip enable (E1), address burst control

inputs (ADSP, ADSC, ADV) and write control inputs (Bx,

BW, GW) are synchronous and are controlled by a positiveedge-triggered clock input (CK). Output enable (G) and power

down control (ZZ) are asynchronous inputs. Burst cycles can

be initiated with either ADSP or ADSC inputs. In Burst mode,

subsequent burst addresses are generated internally and are

controlled by ADV. The burst address counter may be

configured to count in either linear or interleave order with the

Linear Burst Order (LBO) input. The Burst function need not

be used. New addresses can be loaded on every cycle with no

degradation of chip performance.

Flow Through/Pipeline Reads

The function of the Data Output register can be controlled by

the user via the FT mode pin (Pin 14). Holding the FT mode

pin low places the RAM in Flow Through mode, causing

output data to bypass the Data Output Register. Holding FT

high places the RAM in Pipeline mode, activating the risingedge-triggered Data Output Register.

DCD Pipelined Reads

The GS8161E18D(GT/D)/GS8161E32D(D)/GS8161D36D(GT/D) is

a DCD (Dual Cycle Deselect) pipelined synchronous SRAM.

SCD (Single Cycle Deselect) versions are also available. DCD

SRAMs pipeline disable commands to the same degree as read

commands. DCD RAMs hold the deselect command for one

full cycle and then begin turning off their outputs just after the

second rising edge of clock.

Byte Write and Global Write

Byte write operation is performed by using Byte Write enable

(BW) input combined with one or more individual byte write

signals (Bx). In addition, Global Write (GW) is available for

writing all bytes at one time, regardless of the Byte Write

control inputs.

Sleep Mode

Low power (Sleep mode) is attained through the assertion

(High) of the ZZ signal, or by stopping the clock (CK).

Memory data is retained during Sleep mode.

Core and Interface Voltages

The GS8161E18D(GT/D)/GS8161E32D(D)/GS8161D36D(GT/D)

operates on a 3.3 V or 2.5 V power supply. All input are 3.3 V

and 2.5 V compatible. Separate output power (VDDQ) pins are

used to decouple output noise from the internal circuits and are

3.3 V and 2.5 V compatible.