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ADG1234 analog inputs clamping diodes

We plan to use the ADG1234 in one of our products. It will be powered with +/-15V rails (see picture attached). We would like to protect it against over voltages up to +/-25V. There is a 220R series resistor with each analog input we want to protect. We can't increase the resistor value to keep enough BW.

So my questions are :

  1. Are there clamping diode to VSS in the ADG1234?
  2. In order to handle the max current in over voltage condition (around 50mA), could you please suggest protection diodes (connected between input/output terminals and VDD, VSS) with very low capacitance (let's say 1pF total max.) which can meet the ADG1234 specs & our 25V input protection requirement?

Thank you in advance,

  • Hi,

    It sounds like one of our over-voltage protection switches may be a better fit for your application. Have a look at the ADG5243F. This is a triple SPDT Switch that has over-voltage protection on the source side of up to +/-55 V.  Once the input to the switch exceeds the supply voltage by 0.7 V the switch goes high impedance blocking the fault from the down stream circuitry. This would eliminate the requirement for your resistor and any diodes on the input.

    Let me know if this would be a fit for your application



  • Hi David,

    At first flance, the ADG5243F looked good for our application.

    Unfortunately, we needed to use the switch in a SPDT configuration (with

    the high voltage on the SP side), so this IC does not fit.

    In the end we have completely changed the architecture.

    Anyway thanks for your help,


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