Hello everyone!
While doing electrostatic discharge (ESD) testing, it seems that noise is coupling into the MR pin
of the TPS3823 causing my microcontroller to be reset. I took a 0.22 uF capacitor and soldered this between pins
3 (MR) and 2 (GND) and now I am not seeing the unexpected resets during an electrostatic discharge.
Here is a screen shot of the circuit:
I was wondering if there is a better value to use for the capacitor? The 2k resistor (R200) and the added
capacitor should give a low pass cutoff frequency of:
f = 1/ (2 * pi* 2k * 0.22 uF ) = 361 Hz
1.) When solving ESD problems how should I be thinking about the low pass filter here? Should I try to move as close as possible to DC? (0 Hz for the cutoff?)
2.) What about the impedance of the capacitor? We know that the impedance for a capacitor is
Zc = 1 / (j*w*C)
As frequency gets larger the impedance of the capacitor decreases routing noise to ground.
3.) If I had my choice between difference values of capacitors such as 0.68 uF, 22 uF or 47 uF what would be the best
selection for this problem I am having with the TPS3823.
Thank you.
-Mike
