cancel
Showing results for 
Search instead for 
Did you mean: 

STM32 ADC protection diode

jean_prieur
Associate III
Posted on September 18, 2013 at 11:58

Hello,

I want to protect my ADCs from overvoltage and ESD, and limiting the input to 3.3V.

This is my schematic:

0690X0000060514QAA.png

There is a voltage divisor to convert 5V >  3.3V.  The top resistor is also used as the diode resistor.

There is a lot of special diodes in the market: TVS, zener... Do you know a part number which can fit for my application ?

Thanks !
3 REPLIES 3
jpeacock2399
Associate II
Posted on September 18, 2013 at 15:54

I use the ST USBLC6-4 series TVS diode arrays.  They are intended for USB but work well as a low capacitance TVS diode.  The array clamps the input line to the power rails.   I like the USBLC6 since it has either 2 or 4 diodes for multiple channels plus a fast breakdown diode between ground and VDD. 

For single diodes and no line clamping I use the NXP PESD series TVS diodes for 5V and 3.3V lines.  For 24V outputs (common in industrial process control) I use the Vishay QSBT40 TVS diode array.

I also use zeners to clip the input voltage to an ADC channel in cases where the ADC VREF is below the VDD power rail.

  Jack Peacock
emalund
Associate III
Posted on September 18, 2013 at 17:38

a Zener is too slow for transient suppression

Erik
jean_prieur
Associate III
Posted on September 19, 2013 at 16:58

Thanks ! I also use the PESD5V0S1 for my resistive touchpad input. I think I will use it for my ADC inputs.