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Groups > comp.arch.embedded > #27372
| From | John Speth <johnspeth@yahoo.com> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: Can a piezo buzzer generate damaging voltages? |
| Date | 2017-10-11 16:46 -0700 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <ormah5$4ue$1@gioia.aioe.org> (permalink) |
| References | <orh3ef$1qpp$1@gioia.aioe.org> <orm8cb$25t$1@gioia.aioe.org> |
On 10/11/2017 4:10 PM, Chris wrote: > 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 Thanks, Chris. You raised a good point I hadn't considered (capacitance). I suppose the buzzer has a built-in load resistor because the circuit doesn't have a discrete load. The data sheet doesn't say one way or the other. I'll need to look into that. JJS
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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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