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Usage of MultiLayer Varistor for ESD protection on the NRST signal of STM32 M0 microcontroller

Question asked by sathiyamoorthy.arunk on Jan 4, 2016
Latest reply on Jan 6, 2016 by greg_stm

We are using STM32L051C6 microcontroller in our design. We also use the STWD100 Watchdog chip too provide a reset when the code hangs up. This is added as a redundance to the internal watchdog chip of the microcontroller. We also have put a multilayer varistor (DC voltage of 5.6V) on the NRST signal for ESD protection purpose. Additional RC delay network is added prior to the Varistor on the NRST signal.

Is this a recommended practice to use a varistor on the NRST signal of the microcontroller for ESD protection purpose. The circuit is powered up using a 3V battery.