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PGA460: Transducer Selection

Lucas Barzotto
Intellectual 310 points
Part Number: PGA460
Other Parts Discussed in Thread: TDC1000,

Hello, I'm planning on using a PGA460 to drive the following transducer:

http://www.globalmarket.com/product-info/dual-frequency-ultrasonic-sensor-8249174.html

The idea is to use the transducer underwater and measure the depth of a tank (about 5m). Do you think this transducer and PGA460 (or maybe TDC1000) are suitable for the project? If not, what transducer would you recommend?

Thanks,

Lucas

  • 0
    TI__Mastermind 27950 points

    Hi Lucas,

    Yes, if this transducer is intended to be submerged, and your maximum distance requirement is only 5m, then the PGA460 is a suitable option. The TDC1000 can be considered as a secondary/alternative.

    The PGA460 will support both the 40kHz and 200kHz modes of this transducer. I do recommend that you use a transformer driver to properly excite this transducer to generate sufficient sound pressure level. You can find a list of transformer options for both low (40kHz) and high (200kHz) frequency compatible transducers here: PGA460 Transducer & Transformer Listing

  • 0 in reply to Akeem Whitehead
    Intellectual 310 points

    Thanks for your answer Akeem,

    According to the seller, the input voltage Vp-p is around 1000Vpp. Is PGA460 able to drive this transducer using a transformer? How about TDC1000? Which transformer would be suitable?

  • 0 in reply to Lucas Barzotto
    TI__Mastermind 27950 points

    Hi Lucas,

    The PGA460 is better suited to handle high voltage transducers due to its integrated low-side FETs rated for 500mA of drain-source current. The TDC1000 is exclusively a pre-driver (no integrated high current FETs).

    You should note that though the maximum input voltage is around 1000Vpp, you may not necessarily need to generate this much voltage to create a detectable amount of sound pressure level. The transformers listed in the aforementioned spreadsheet mostly have push-pull turns ratios of 1:1:10, meaning if you supply the maximum allowable voltage of 15V at the center-tap of the transformer's primary winding, you can generate +/-150V or 300Vpp. This would only be third of your transducers drive voltage, but worth exploring. If you can get away with this drive voltage, it will also save you power. If not, you may need to find or request a custom transformer for a larger turns ratio.

    Another alternative is to use the PGA460 as a pre-driver for external FETs with a larger drain-source rating. For example, if an external FET has a rating of 100V drain-source, you could use a center tap voltage of 50V max. Then, when using 1:1:10 transformer, your excitation at the secondary could be as high as  1000Vpp. See the PGA460 Full-Bridge Driver Solutions for Ultrasonic Transducers (Rev. A) for an example on how the PGA460 can be used as a pre-driver for external FETs.