HA16117F Series

CMOS Watchdog Timer

Description

The HA16117F Series of ICs make a micro-processor (MPU) system fail-safe by monitoring its power

supply to detect voltage drops, and monitoring a P-RUN (program running) pulse to detect system crashes.

Also referred to as watchdog timers, these devices are essential in systems that aim for high levels of crash

protection. Fabricated by a CMOS process, they consume little power and are ideally suited for battery-

operated systems.

These ICs are available in versions for industrial and communications equipment and automotive

applications, as well as for consumer products.

Functions

• Power-on reset

 Sends a RES signal to the MPU for a fixed time at power-on

• Watchdog timer (WDT)

 Monitors a P-RUN signal from the MPU and sends the MPU a RES signal if P-RUN departs from a

set frequency range

• Auto-reset

 Outputs RES signals to the MPU at clocked intervals while P-RUN remains abnormal

• Supply voltage supervision

 Outputs a low RES signal if the supply voltage (same as the MPU's V

level (V

matching system requirements (see ordering information)

Features

• Low power consumption : Operating (ACC pin low) = 0.5 mW (Typ)

: Standby (ACC pin high) = 0.2 mW (Typ)

• Watchdog timer on/off control by ACC input signal

• Independent auto-reset high and low times (t

• Watchdog monitoring by frequency filtering (independent of duty cycle)

• High-precision low voltage detection (±2%)

• Space- and weight-saving 8-pin SOP package