The SP791 is a low-power microprocessor supervisory circuit that integrates a myriad of components involved in discrete solutions to monitor power-supply and battery-control functions in µP and digital systems. The SP791 offers complete µP monitoring and watchdog functions.
The SP791 is a low‑power microprocessor supervisory circuit that provides voltage monitoring, battery‑backup switching, reset and watchdog functions for portable, battery‑powered digital systems. It integrates a voltage monitor, backup‑battery monitor, manual‑reset input, power‑fail comparator and watchdog timer in a single 16‑pin package.
Key electrical characteristics include a 0 V to 5.5 V operating voltage range, 75 µA maximum supply current, 250 mA output in normal mode and 25 mA in battery‑backup mode. The device is offered in Plastic DIP and narrow SOIC packages and includes pin‑compatible options for the MAX791 family.
| Maximum Operating Supply Current | 75 µA |
|---|---|
| Battery Backup Current | 1.0 µA |
| Battery Standby Current | 0.1 nA |
| Vec Mode Output Current | 250 mA |
| Battery Mode Output Current | 25 mA |
| Operating Voltage Range | 0 – 5.5 V |
| Reset Threshold Voltage | 4.50 – 4.75 V |
| Watchdog Timeout Period | 1.0 – 2.25 s |
The SP791 draws up to 75 µA of supply current.
The RESET output remains low for 200 ms after the manual‑reset input returns high.
The watchdog timeout can be set between 1.0 s and 2.25 s.
Multiply the capacitor value in nF by 2.1 ms to get the timeout period.