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PGA460: PGA460 INP and INN are unable to receive waveform when I connect 300kHz ultrasonic sensors with full-bridge direct drive in bi-static mode.

user4058462
Prodigy 10 points
Part Number: PGA460

Hi

 There are some questions when I use full-bridge direct drive in bi-static mode . When I connect 300KHZ ultrasonic sensors , PGA460 INP and INN are unable to receive waveform when OUTA and OUTB transmit normally .  But when I connect 40KHZ ultrasonic sensors , PGA460 INP and INN can receive waveform when OUTA and OUTB transmit normally . I have tried do somehing to solve it , but failed. Please give me some advice .

  • 0
    TI__Mastermind 27780 points
    Hello user4058462,
    Can you list the part number or link to the datasheet of the 300kHz transducer you are using?
    Can you attach the oscilloscope screen capture of the 300kHz driver at OUTA/B?

    INN should be grounded through C_INN, as well as the negative terminal of the receiving transducer. Have you updated the values of C_INP and C_INP for the 300kHz frequency (see PGA460 datasheet table 101 for calculations).

    Can you share the schematic for your bi-static full-bridge circuit? Note, we have observed issues with the EVM's full-bridge implementation. It is possible for the driver to latch with additional supporting circuitry (detailed full-bridge implementation to be made available as an Application Note and TI Design in the near future).

    I would recommend you attempt the half-bridge driver first. If you can successfully use a half-bridge bi-static mode with the 300kHz transducers, we can further debug the full-bridge mode.