bq2202

Features:

Power monitoring and switching fornonvolatilecontrolofSRAMs
Write-protectcontrol
Input decoder allows control of upto2banksofSRAM
3-voltprimarycellinput
3-volt rechargeable battery in-put/output
Reset output for system power-on reset
Less than 10ns chip enable propagationdelay
5%or10%supplyoperation


Pinout




Specifications

Symbol	Parameter	Value		Unit	Notes
VCC	VCC relative to VSS	-0.3 to +7.0		V
VT	DC voltage applied on any pin ex- cluding VCC relative to VSS	-0.3 to +7.0		V	VT VCC + 0.3
TOPR	Operating ambient temperature	0 to +70		°C	Commercial
		-40 to +85		°C	Industrial "N"
TSTG	Storage temperature	-55 to +125		°C
TBIAS	Temperature under bias	-40 to +85		°C
TSOLDER	Soldering temperature	260		°C	For10seconds
IOUT	VOUT current	200		mA

Description

The CMOS bq2202 SRAM Nonvolatile Controller With Reset provides all the necessary functions for converting one or two banks of standard CMOS SRAM into nonvolatile read/write memory.


A precision comparator monitors of bq2202 the 5V 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 is switched from the VCC supply to the battery-backup supply as VCC decays. On a subsequent power--up, the V_OUT supply bq2202 is automatically switched from the backup supply to the VCC supply. The external SRAMs are write-protected until a powervalid condition exists. The reset output provides power-fail and power-on resetsforthesystem.


During power-valid operation, the input decoder of bq2202 selects one of two banksofSRAM.