APPLICATION NOTE 474

Precision DAC and Watchdog Improve Analog Output Safety

By: Damian Anzaldo

Abstract: Using a DAC and a microprocessor supervisor, the system safety can be improved in industrial controllers, programmable-logic controllers (PLC), and data-acquisition systems. The analog output is set to zero-scale (or pin-programmable midscale) when a microprocessor failure, optocoupler failure, or undervoltage condition occurs. A simple application is shown on how to implement this function.