bq2201
SRAM Nonvolatile Controller Unit
Features General Description вћ¤ Power monitoring and switching
for 3-volt battery-backup applications The CMOS bq2201 SRAM Nonvolatile
Controller Unit provides all necessary
functions for converting a standard
CMOS SRAM into nonvolatile
read/write memory. вћ¤ Write-protect control
вћ¤ 3-volt primary cell inputs
вћ¤ Le than 10ns chip-e nable
propagation delay
вћ¤ 5% or 10% supply operation A precision comparator monitors the
5V VCC input for an out-of-tolerance
condition. When out of tolerance is
detected, a conditioned chip-enable
output is forced inactive to writeprotect any standard CMOS SRAM. Pin Connections During a power failure, the external
SRAM is switched from the V CC
supply to one of two 3V backup supplies. On a subsequent power-up, the
SRAM is write-protected until a
power-valid condition exists.
The bq2201 is footprint-and timingcompatible with industry standards with the added benefit of a
chip-enable propagation delay of
less than 10ns. Pin Names NC 1 16 NC VOUT 2 15 VCC VOUT Supply output BC1—BC2 3-volt primary backup cell inputs THS Threshold select input CE chip-enable active low input CECON Conditioned chip-enable output VOUT 1 8 VCC NC 3 14 NC BC2 2 7 BC1 BC2 4 13 BC1 THS 3 6 CECON NC 5 12 NC VCC +5-volt supply input VSS 4 5 CE THS 6 11 CECON VSS Ground NC 7 10 NC NC No Connect VSS 8 9 CE 8-Pin Narrow DIP or SOIC …
