0

I am planning to add a active piezo element audio buzzer with built-in driver (BESTAR BPT-14X or LOUDITY LD-BZEL-PB04-1408 ) to my recent quite complex MCU project.

These buzzers come with built in generators, so can be driven directly by DC voltage. I have a square pulse output from PNP transistor that I also monitor with MCU. I would like to add acoustic signaller here - so connect buzzer in parallel.

I heard from many sources (sadly mostly guesses) that these active PZT come with internal coil, so they can cause large voltage spikes on their positive pin (in my case connected also to MCU input - so any spike could easily kill MCU). Is that a fact? In datasheets there are no mentions about this. I would test this, but my scope in not in working condition right now... If this is correct, what kind of protection would you recommend? Schottky diode is probably wrong since I am drivnig with 3,3V. Maybe TVS or zenr diode?

HeliTux
  • 195
  • 1
  • 7
  • https://electronics.stackexchange.com/questions/18212/whats-the-third-wire-on-a-piezo-buzzer shows about the simplest circuit you're likely to encounter. No coil. Should be no problem with a PNP high-side-switch. If you can tap into the transistor base driver, your MCU could switch the oscillating resistor directly - no PNP required. – glen_geek Apr 23 '20 at 19:46
  • I have a PNP as part of signal inverter output to feed into MCU counter, so it will be there anyway. Anyway I see that kind of piezo self driving structure for the first time - very interesting and clever. So I see that there should be no voltage spikes or other dangerous transitions on PZT pins. – HeliTux Apr 23 '20 at 21:38

0 Answers0