The TPS3617 and TPS3618 are battery-backup supervisors that monitor 5 V supplies. They provide a battery-backup function ideal for applications that require data retention of CMOS RAM during fault conditions. When the voltage at VDD drops below a preset threshold (VIT), the active low push-pull RESET output asserts, and VOUT switches from VDD to VBAT. When VDD rises above the trip threshold, VOUT switches immediately from VBAT to VDD. The RESET output remains low until the delay time (td) expires. During power on, RESET is asserted when the supply voltage (VDD or VBAT) goes higher than 1.1 V.

The PFI and PFO pins are provided if additional voltage monitoring is needed. If the voltage at PFI is less than 1.15 V, the push-pull PFO pin will assert low. When the voltage at PFI exceeds the threshold voltage, PFO will go high.

These devices also feature a watchdog timer pin (WDI) that monitors processor activity and asserts RESET if the the processor is inactive longer than the watchdog timeout period. If the watchdog timer is not used, the WDI pin should be left floating.

The TPS3617 and TPS3618 are available in an 8-pin MSOP package and are characterized for operation over a temperature range of -40°C to +85°C.

• Supply Current of 40 µA (Max)
• Battery Supply Current of 100 nA (Max)
• Precision 5-V Supply Voltage Monitor, Other Voltage Options on Request
• Backup-Battery Voltage Can Exceed VDD
• Watchdog Timer With 800-ms Time-Out
• Power-On Reset Generator With Fixed 100-ms Reset Delay Time
• Voltage Monitor for Power-Fail or Low-Battery Monitoring
• Battery Freshness Seal (TPS3617 Only)
• 8-Pin MSOP Package
• Temperature Range: -40° to +85°C
• APPLICATIONS
  • Fax Machines
  • Set-Top Boxes
  • Advanced Voice Mail Systems
  • Portable Battery Powered Equipment
  • Computer Equipment
  • Advanced Modems
  • Automotive Systems
  • Portable Long-Time Monitoring Equipment
  • Point-of-Sale Equipment