FEATURES

Power Monitoring and Switching for

Non-Volatile Control of SRAMs

Input Decoder Allows Control of 1 or 2 Banks

of SRAM

Write-Protect Control

3-V Primary Cell Input

3.3-V Operation

Reset Output for System Power-On Reset

Less than 20-ns Chip Enable Propagation

Delay

Small 16-Lead TSSOP Package

APPLICATIONS

NVSRAM Modules

Point-of-Sale Systems

Facsimile, Printers and Photocopiers

Internet Appliances

Servers

Medical Instrumentation and Industrial

Products

DESCRIPTION

The CMOS bq2205 SRAM non-volatile controller

with reset provides all the necessary functions for

converting one or two banks of standard CMOS

SRAM into non-volatile read/write memory.

A precision comparator monitors the 3.3-V VCC

input for an out-of-tolerance condition. When

out-of-tolerance is detected, the two conditioned

chip-enable outputs are forced inactive to

write-protect both banks of SRAM.

Power for the external SRAMs, VOUT, is switched

from the VCC supply to the battery-backup supply

as VCC decays. On a subsequent power-up, the

VOUT supply is automatically switched from the

backup supply to the VCC supply. The external

SRAMs are write-protected until a power-valid

condition exists. The reset output provides

power-fail and power-on resets for the system.

During power-valid operation, the input decoder, A,

selects one of two banks of SRAM.