I have a question about piezoelectric component and microcontroller connection circuit.

I use 7BB-20-6L0 Murata piezo. Here is the datasheet - Link

Here is my current variant:

enter image description here

Is this schematic correct and safe? Are all this components necessary? (Is there any need in D1 and R2?)

And one more moment...

I'd like to use two MCU pins to increase the voltage level: enter image description here

What should be done in this case in order to get maximum safety?

Thank you in advance!!


enter image description here

  • \$\begingroup\$ piezo datasheet ? \$\endgroup\$ Mar 22 '18 at 20:25
  • \$\begingroup\$ Sorry, I've forgotten to add this info... I'll edit my question. \$\endgroup\$
    – Nick
    Mar 22 '18 at 20:29
  • \$\begingroup\$ For schematic B, how can you toggle pin 1 and pin 2 at the same time, alternating between '1' and '0'? \$\endgroup\$
    – user105652
    Mar 22 '18 at 21:58
  • \$\begingroup\$ Half of period there will be '0' at pin 1 and '1' at pin 2 and another half vice versa. \$\endgroup\$
    – Nick
    Mar 22 '18 at 22:19
  • \$\begingroup\$ @Sparky256 on many microcontrollers, you can modify the state of a whole register of pins at once, i.e. 8 pins at a time for 8 bit microcontrollers. \$\endgroup\$
    – BeB00
    Mar 22 '18 at 22:40
  • C1 prevents Ag migration in high humidity with DC across piezo
  • R1 C1 also matches impedance of this buzzer ... 10nF, 1kΩ (30%), (6.3kHz)
  • D1, D2 protects LSI chip if the board is dropped producing large V which may wound chip.
  • R2 reduces DC

maybe MMBD7000L dual diode is ok for you

Regarding differential drive from MCU , that is fine as 20mm piezo disks are typically 1 kOhm and less if above +/-10. So +/-3.3 or 5V is no sweat. You may want to use a natural resonant frequency in a self oscillating loop to improve loudness. For even louder sound an SMT stepup transformer can be used.

Sometimes you have to dig around on the JP site to get more details not in the English datasheet. They hold back broadcasting some information for at least 5 yrs and in many cases even special parts are not available for export for the same period. That's been going on for as long as I have practised.

enter image description here

  • \$\begingroup\$ Thank you for the answer! So, should I modify Schematic B to Schematic C? (I've updated the question with new schematic) \$\endgroup\$
    – Nick
    Mar 23 '18 at 22:26

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