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Re: Can a piezo buzzer generate damaging voltages?

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On 10/10/17 00:15, John Speth wrote:
> My team is being asked to find out why a circuit is failing for no
> obvious reason. The circuit has a piezo buzzer (CEP2242 from CUI, Inc).
> The buzzer is driven by a MCU driven FET that completes a circuit like
> this: high side power 3.3V -> buzzer -> FET -> ground (BSS123LT1 FET on
> the low side).
>
> Does anybody have any experience with the possibility of a piezo buzzer
> generating damaging voltage spikes when dropped? We have no protection
> diodes on this part of the circuit.
>
> At this stage, we have no information of exactly what's failing. We do
> have evidence that some failed units have been dropped. I'm following
> through on a hypothetical failure path which we need to either consider
> further or discard.
>
> Thanks - JJS
>

Piezo buzzers are capacitive, so do you have a load resistor across
the piezo ?, otherwise no current will flow other than for the first
pulse, which charges up the capacitance. A load resistor might fix
the spike problem, though clamp diodes to ground and to the +3.3
volt rail, to limit excursions, would be a better solution...

Regards,

Chris

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Thread

Can a piezo buzzer generate damaging voltages? John Speth <johnspeth@yahoo.com> - 2017-10-09 17:15 -0700
  Re: Can a piezo buzzer generate damaging voltages? Clifford Heath <no.spam@please.net> - 2017-10-10 13:55 +1100
  Re: Can a piezo buzzer generate damaging voltages? o pere o <me@somewhere.net> - 2017-10-11 11:08 +0200
    Re: Can a piezo buzzer generate damaging voltages? Clifford Heath <no.spam@please.net> - 2017-10-11 22:37 +1100
      Re: Can a piezo buzzer generate damaging voltages? o pere o <me@somewhere.net> - 2017-10-16 09:56 +0200
  Re: Can a piezo buzzer generate damaging voltages? Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-10-11 23:10 +0000
    Re: Can a piezo buzzer generate damaging voltages? John Speth <johnspeth@yahoo.com> - 2017-10-11 16:46 -0700
      Re: Can a piezo buzzer generate damaging voltages? "petrus bitbyter" <petrus.bitbyter@hotmail.com> - 2017-10-12 15:32 +0200
        Re: Can a piezo buzzer generate damaging voltages? Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-10-12 14:31 +0000
        Re: Can a piezo buzzer generate damaging voltages? John Speth <johnspeth@yahoo.com> - 2017-10-12 13:48 -0700
          Re: Can a piezo buzzer generate damaging voltages? Jan Coombs <jenfhaomndgfwutc@murmic.plus.com> - 2017-10-15 18:12 +0100

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