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OPA1678: Using OPA1678 to drive a piezoelectric buzzer

SHENG YANG
Expert 1190 points
Part Number: OPA1678
Other Parts Discussed in Thread: TLC555, OPA192

Tool/software:

Hi Team,

As shown in the diagram below, I would like to use two OPA1678 operational amplifiers to drive a piezoelectric buzzer. One of them will serve as an inverting amplifier, while the other will serve as a non-inverting amplifier.
The input voltage in the diagram ranges from DC 5V to 12V, and the analog switch input is a PWM signal from the SOC with a frequency ranging from 1kHz to 4kHz. The two OPA1678 amplifiers will output complementary signals with the same frequency to drive the piezoelectric buzzer.Is this plan feasible?

1、Can OPA1678 be used for square wave signal input? (Frequency 1KHZ~4KHZ).

Thanks

  • 0
    TI__Mastermind 22010 points

    Hi Sheng, 

     Does the Piezo need to be driven with plus and minus signal? If not a 555 timer would be more suitable. Please look at the TLC555 timer in the link below. 

    TLC555

    Here is an example using the monostable mode for the TLC555 that generates a 1kHz square wave on the output. The timing can be adjusted by using a potentiometer for R1. 

    TLC555 TINA Ti Simulation:

    TLC555 Monostable 2.TSC

    The OPA1678 is a high performance audio amplifier. The input common mode voltage range is VCC-2V as shown below where your input signal goes to VCC.

    If you need to use an op amp you may consider the OPA192 that has inputs that can be used as a comparator that would be better suited than the OPA1678. 

    OPA192

    You may also consider using a comparator in a square wave oscillator circuit as shown below.

    TLV1832

     

    Best Regards, 

    Chris Featherstone

  • 0 in reply to Chris Featherstone
    Expert 1190 points

    hi.Chris

    thank you for your reply.

    My original intention of designing is to use ±12V to drive the piezoelectric buzzer. The OPA1678 is used in the figure to form a common-phase and inverting amplifier circuit to generate +12V and -12V voltages at both ends of the buzzer.
    Please help evaluate whether the OPA1678 can input a square wave signal. Or maybe find an op amp to replace the OPA1678 that can drive the buzzer. Thank you.

  • +1 in reply to SHENG YANG
    TI__Mastermind 22010 points

    Hi Sheng, 

    As mentioned above the OPA1678 has a common mode range that is 2v below the supply rail where in your application you are driving to the supply rail which is not recommended. For this reason I recommended the OPA192 that has rail to rail inputs if an op amp is needed. I think a better option would be to consider a comparator that can do the square wave oscillator circuit as shown in my last reply.

    Best Regards, 

    Chris Featherstone