I need a watchdog timer to control some "failsafe" relays.
There are a lot of watchdog chips, but the outputs are typically designed to create a momentary pulse to toggle a reset line. What I need is the output to hold some relay coils energized until the timeout, at which point the relay coils are de-energized. The coils should remain de-energized until the timer is reset with a tickle on the input. If the input is "tickled" before the timeout, then the timer should be reset and the output should continue to hold the coils energized.
Does anyone know of a chip that can do this?
Ideally, the output should keep the relays de-energized at power-on until the first "tickle" of the watchdog, but that is not a hard requirement and it would be OK if the timer starts and the output drives the relay coils at power on.
Thanks!
There are a lot of watchdog chips, but the outputs are typically designed to create a momentary pulse to toggle a reset line. What I need is the output to hold some relay coils energized until the timeout, at which point the relay coils are de-energized. The coils should remain de-energized until the timer is reset with a tickle on the input. If the input is "tickled" before the timeout, then the timer should be reset and the output should continue to hold the coils energized.
Does anyone know of a chip that can do this?
Ideally, the output should keep the relays de-energized at power-on until the first "tickle" of the watchdog, but that is not a hard requirement and it would be OK if the timer starts and the output drives the relay coils at power on.
Thanks!