bq2205LY Datasheet | Texas Instruments

SLUS581 - FEBRUARY 2004 POWER MONITORING AND SWITCHING CONTROLLER FOR 3.3ĆV SRAM Features D Power Monitoring and Switching for Non-Volatile Control of SRAMs D Input Decoder Allows Control of 1 or 2 Banks of SRAM D Write-Protect Control D 3-V Primary Cell Input D 3.3-V Operation D Reset Output for System Power-On Reset D Less than 20-ns Chip Enable Propagation Delay D Small 16-Lead TSSOP Package APPLICATIONS D NVSRAM Modules D Point-of-Sale Systems D Facsimile, Printers and Photocopiers D Internet Appliances D Servers D 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 parator 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. Main Supply VDC GND Backup Supply VDC GND From Address Selector bq2205LYPW 12 VCC BW 15 1A RST 16 11 CE VOUT 13 9 BCP 4 VSS 5 VSS 8 VSS CECON1 10 CECON2 14 VCC To...