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[ LM48560 ] Protection Circuit for Back EMF

Kenichiro
Mastermind 9165 points
Other Parts Discussed in Thread: LM48560

[ LM48560 ] Protection Circuit for Back EMF

Hi,

My customer has being consider whether any kind of protection circuit is necessary for output stage to prevent damage from reverse voltage due to back emf effect.

Their concern is that the excess reverse voltage would be generated due to change of piezo shape, in this situation, LM48560 suppose to be exposed over voltage condition at output pins.

As my understanding, LM48560 output stage has no over voltage voltage protection, so it could be necessary. However if you have different aspect, please let me know.

Thanks,
Ken
  • 0
    Expert 1220 points

    Back-EMF or inductive kickback?

    I presume you really mean inductive kickback. More than likely the output stage has CMOS diodes for ESD purposes, but these will rarely be sized for inductive kickback. A typical solution is to include Schottky diodes on the output that are sized to the current you expected. 
    The key is to clamp the voltages no more than 300mV beyond the rail else, you can inject charge into the substrate of the device and BOOM!

    -Ken

  • 0 in reply to Ken Dillinger
    Mastermind 9165 points
    Thanks, Ken!
    (really sorry that I missed reply to you.)

    This is helpful!
    Regards,
    Ken