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Original question:

DRV2700EVM-HV500 - high capacitance load

Could DRV2700 drive this piezoelectric ceramics

Gabriel Wang1
Genius 3825 points
Other Parts Discussed in Thread: DRV2700, DRV2700EVM-HV500

Dear Expert

This is our piezoelectric ceramics spec .

Our application's Voltage is related to power, the highest peak value is several hundred V, the specific maximum has not been measured.The capacitance of the two pieces together is about 2.6 nF.

,

Could DRV2700 drive this piezoelectric ceramics ?

BR

Gabriel Wang

  • 0
    TI__Genius 13610 points

    Hello Gabriel,

    Is that 2nd chart showing a resonance or driving frequency of 35kHz?

    Best Regards 

    Carson

  • 0 in reply to Carson Allen
    Genius 3825 points

    Dear Carson

    The resonant frequency Fs is 35.94khz.

    Let me elaborate.

    1.We choose DRV2700 to drive two parallel piezoelectric ceramics in resonant state through DRV2700. The piezoelectric ceramic plate is a capacitive load, and the capacitance of two parallel piezoelectric ceramics is about 2.6nF.When two piezoelectric ceramic plates are connected in parallel, the specific parameters are shown in FIG. 4 as shown in the admittance diagram. The resonant frequency Fs is 35.94khz, the resonant impedance R1 is 176.997757, the driving signal is ac sine wave, and the voltage peak-to-peak value may reach 200-300VPP.Please help evaluate whether DRV2700 and DRV2700EVM-HV500 can meet the requirements.If the requirements cannot be met, is there a recommended solution?

    2.The DRV2700 datasheet shows that the chip can support driving piezoelectric ceramic chip, but it can be seen from the schematic diagram of the development plate drv2700evm-hv500 that the development plate does not lead to pin13 and pin14 driving piezoelectric ceramic chip.What is the application scenario of drV2700EMV-HV500 development board?Can't support drive piezoelectric ceramic chip?

  • 0
    Prodigy 10 points

    Hello Allen,

             Yes, the resonance frequency Fs is 35.94kHz， the driving frequency is the same as resonance frequency。 But the Load will be changed，lead to the resonance frequency be changed as well。  The resonance frequency is in the range of 0~100kHz.

  • 0 in reply to bernard xiao bernard xiao
    TI__Genius 13610 points

    This device is very limited in its effectivity to drive high voltages past 20KHz so this part would not be a good fit even with such a small capacitance. Fundamental limitation of its integrated boost to provide the current as the frequency increases. There is no part I can recommend that would be able to get 200-300Vpp at 35KHz

    Here is bandwidth charts and in bottom right with 200Vpp capability bandwidth is only 10KhZ, and using it in its fly back configuration would get you higher voltages but still lower bandwidth