The TPS3610 family of supervisory circuits monitors and controls processor activity by providing backup-battery switchover for data retention of CMOS RAM. Other features include an additional power-fail comparator, low-line indication, watchdog function, battery-status indicator, manual switchover, and write protection for CMOS RAM.

The TPS3610 family allow usage of 3-V or 3.6-V lithium batteries as the backup supply in systems with, e.g., VDD = 1.8 V. During power-on, RESET\ is asserted when the supply voltage (VDD or VBAT) becomes higher than 1.1 V. Thereafter, the supply-voltage supervisor monitors VDD and keeps RESET\ output active as long as VDD remains below the threshold voltage VIT. An internal timer delays the return of the output to the inactive state (high) to ensure proper system reset. The delay time starts after VDD has risen above the threshold voltage VIT . When the supply voltage drops below the threshold voltage VIT, the output becomes active (low) again.

The product spectrum is designed for supply voltages of 1.8 V and 5 V. The circuits are available in a 14-pin TSSOP package. TPS3610 devices 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 Supply-Voltage Monitor, 1.8 V, 5 V; Other Options on Request
• Watchdog Timer With 800-ms Time-Out
• Backup-Battery Voltage Can Exceed VDD
• Power-On Reset Generator With Fixed 100-ms Reset Delay Time
• Battery-OK Output
• Voltage Monitor for Power-Fail or Low-Battery Monitoring
• Manual Switchover to Battery-Backup Mode
• Chip-Enable Gating ... 3 ns (at VDD = 5 V) Max Propagation Delay
• Battery-Freshness Seal
• 14-pin TSSOP Package
• Temperature Range ... –40°C to 85°C
• typical 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