bq2502
Features
® Power monitoring, backup supply, and switching for 3V batterybackup applications
® Write-protect control
® Input decoder for control of up to 2 banks of SRAM
® 3-volt backup power output
® Internal 130m Ah lithium-coin cell
® Reset output for system power-on reset
® Less than 10ns chip-enable propagation delay
® 5% or 10% supply operation
Integrated Backup Unit
General Description
The CMOS bq2502 Integrated Backup Unit provides all the necessary functions for converting one or two banks of standard CMOS SRAM into nonvolatile read/write memory.
A precision parator monitors 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 internal battery-backup supply as VCC decays. On a subsequent power-up, the VOUT supply is automatically switched from the internal lithium supply to the...
