IMP1232LP

The IMP1232LP/LPS microprocessor supervisor can halt and restart a "hung-up" or "stalled" microprocessor, restart a microprocessor after a power failure, and debounce and interface a manual push-button microprocessor reset switch. The low-power supervisors feature 40% lower supply current than the pin compatible Dallas Semiconductor DS1232LP/LPS.

Precision temperature compensated reference and comparator circuits monitor the 5V, VCC input voltage. During power-up or when the VCC power supply falls outside selectable tolerance limits, both the RESET and RESET become active. When VCC rises above the threshold voltage, the reset signals remain active for an additional 250ms minimum, allowing the power supply and system microprocessor to stabilize. The trip point tolerance signal, TOL, selects the trip level tolerance to be either 5- or 10-percent.

Each device has both a push-pull, active HIGH reset output and an open drain, active LOW reset output. A debounced manual reset input activates the reset outputs for a minimum period of 250ms.

Also included is a watchdog timer to stop and restart a microprocessor that is "hung-up". Three watchdog time-out periods are selectable: 150ms, 610ms and 1,200ms. If the ST input is not strobed LOW before the time-out period expires, a reset is issued.

Devices are available in 8-pin DIP, 8/16-pin SO and compact 8-pin MicroSO packages.