• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 31 subscribers
  • Views 263 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PGA460-Q1: How to drive the high frequency probe？

user5901926
Prodigy 60 points
Part Number: PGA460-Q1
Other Parts Discussed in Thread: BOOSTXL-PGA460

Hello ! Recently, I have a problem with driving the high frequency probe (300kHZ ). 

The circuit schematic diagram I used is as follows, but it seems that the probe core is not successfully driven, and the 128 Bytes Echo Recording obtained are all 0x00.

In addition, I have set the FREQ_SHIFT to 1. And when the drive frequency is set to low frequency (40~80kHZ), the Echo Recording is normal (not all 0x00). So I don't understand why this circuit fails in high frequency driving?

At present, I need some suggestions on this issues. I hope you can reply as soon as possible. Thank you very much !

  • 0 in reply to user5901926
    TI__Mastermind 27940 points

    user5901926,

    Assuming you are using the same transformer driver components from the BOOSTXL-PGA460, and that the echo data dump memory is all 0x00, you likely have two issues:

    1) For high-frequency (180-480kHz) transformer driven applications, you need to use a high-frequency compatible transformer. The secondary inductance of the default EVM transformer is too high (mH) to match the resonant frequency of a high-frequency transducer, which requires a secondary inductance in the hundreds of uH. You can find a list of high-frequency transducers and transformers in the PGA460 Transducer & Transformer Listing spreadsheet. Also, remove the matching components in parallel to the transducer (C15 and R38). Alternatively to the transformer drive mode, you can use the direct drive mode to excite your 300kHz transducer.

    2) To capture the echo data dump successfully, ensure you have followed these steps:

    1. Set bit DATADUMP_EN to '1'.
    2. Write to the threshold registers (Px_THR_y) to clear THR_CRC_ERR to '0'.
    3. Send a burst/listen command.
    4. Wait the equivalent length of your preset record length. For guaranteed margin, wait 70ms.
    5. Read back the echo data dump results.