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BQ76200EVM-606: Zener Clamp for the Enable Interface

Part Number: BQ76200EVM-606
Other Parts Discussed in Thread: BQ76200


I am looking into the schematics of BQ76200EVM-606. What's the consideration of zener didodes(D5~D9) and 1k+39.2k resistors in series of the signal path in this design?


  • Hello Peiheng, 

    On the EVM board, these pin is connecting to the external source, the zener diode are used for these pins protection.

    Our AE expert could give more explanation on your further questions. 

    Thank you

  • Hi Peiheng,

    There was a concern that if the EVM user shorted pins together on U1 during evaluation, then reached for the shunts on J7 that they might unexpectedly contact  the battery voltage on the input signals.  So in that condition the zeners clamp the input signals to about 14V with voltage dropped by the 39.2k resistors.  The zeners have a tolerance so the 1k resistors provide a current limit into the zener if a control signal voltage is applied higher than the zener conduction point.

    The BQ76200 control inputs have 1M nominal internal pull downs, so the 10M external resistor patterns shown on the EVM are not populated.