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Tomar - is it necessary to add external diode at RESET pin to VDDX?

Question asked by Yi Wang Employee on Jun 24, 2015
Latest reply on Jul 22, 2015 by Radek Sestak

Dear Team:

 

We are using S12VR and we are reviewing the hardware design with OEM team.

In our application we use a pull-up resistor (4.7K Ohm) to VDDX and a pull-down cap (1nF) to GND at RESET pin.

 

The problem is, if the power (12V) was cut off, the cap would discharge to the resisitor which would cause a high voltage at the pin during a short time (maybe t = R * C), however at that time the internal circuit would drop to low, therefore do you see any risk of this temporary "short circuit"?

 

So we are considering to add an external discharging diode at RESET pin to VDDX in order to avoid this situation. Please share your thought.

 

And we also have a big cap (680uF) at VSUP in case of emergency, but not sure if it helps here.

 

Appreciate your support!

 

Best Regards,

Wang

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