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PGA460: Looking for ultrasonic driver IC for 200 kHz transducer with 50W input power

Andreas Hansen
Intellectual 410 points
Part Number: PGA460
Other Parts Discussed in Thread: DRV8870, TDC1000, TDC7200, DRV8837

Hi

I'm looking for an analog front end for a 200 kHz ultrasonic underwater transducer with 50W tone burst drive power. The device must be used for range measurements.

Have been looking at TI's portfolio and especially the PGA460. It seems to have great software to test and configure the IC for optimum operation.

As far as I can see the PGA460 has the option to operate with a high frequency transducer (adjustable between 180-480 kHz with 1.2kHz steps) that gives 200.4 kHz.

However, as far as I can see, the PGA460 is only capable of delivering 7.5W during tone burst (VVPWR_XF = 15V and I_BURST = 500mA).

Do TI have driver ICs that are capable of delivering up to 50W or are there any ways I can make the PGA460 deliver this amount?

Best Regards,
Andreas

  • 0
    TI__Mastermind 27950 points
    Hello Andreas,

    Yes, the PGA460 can support a transducer with a frequency of 200kHz, but the PGA460 is intended to be used for air-coupled time-of-flight applications. Air-coupled transducers typically do not require more than 7.5W during echo burst transmission.

    Which underwater transducer are you using, what is your targeted range (min and max distance), and what is the specific application?

    I have only seen one underwater transducer which is supported in the PGA460's range of 30-480kHz though the power is rated at 50W; the Prowave 200LM450: prowave.com.tw/.../uwtx.htm

    It may not be necessary to drive the transducer at its maximum rated input power for your intended range. However, to answer your question about alternative drive modes for the PGA460, you can use the OUTA and OUTB pins as control signals for an external driver circuit. This is demonstrated in the "PGA460 Full-Bridge Driver Solutions for Ultrasonic Transducers"appnote ( www.ti.com/.../slaa780.pdf ). In this example, the DRV8870 is used as the actual driver circuit, rather than the PGA460's internal low-side FETs. The DRV8870 has a 3.6A Peak Current Drive with a Wide 6.5-V to 45-V Operating Voltage to better achieve the 50W driver rating you are targeting.
  • 0 in reply to Akeem Whitehead
    Intellectual 410 points

    Hi Akeem

    Thank you for the reply.

    You are completely right about the transducer, I'm refering to the 200LM450. Do you have any experiences with that underwater transducer and maybe in combination with PGA460?

    The specific application is to measure short distances in ocean environments where the transducer is targeting: Sand, mud, small rocks etc. By close, I mean from maybe 30 cm and up to 5-10 meters or whatever turns out to be possible.

    Prowave sells a "Sonar Ranging IC" PW0268 () which I'm considering as well. But it seems to be less configurable and require more external components than the PGA460. Do you have any comments on the comparison between PW0268 vs PGA460.

    Its a good point that its possible to use an external driver circuit. The DRV8870 certainly will be able to deliver sufficient power, but it is right on the limit in terms of the frequency. The datasheet says f_PWM < 200 kHz.

    Best Regards,
    Andreas

  • 0 in reply to Andreas Hansen
    TI__Mastermind 27950 points
    Hi Andreas,

    Unfortunately, we do not have any data on pairing the 200LM450 with the PGA460. I would be interested and willing to perform some testing on this if you have a spare sample to send us.

    Given the transmission medium is water, and not air, I'm not sure how the minimum and maximum ranging would be impacted. Considering the speed of sound in water is 1498m/s, the PGA460's record timer is able to capture all of the ultrasonic data within a 30cm to 10m range.

    The Prowave PW0268 is more so similar to TI's TDC1000+TDC7200 combination in terms of features. Based on PW0268 example schematic, more of the filtering has to be implemented externally, and the driver only allows for a single-ended externally sinking transformer mode. The PGA460 allows offers an integrated push-pull (500mA limit) for stronger echo generation, and handles all the DSP filtering internally. On a high level, the PGA460 is a more integrated solution with a wider feature set.

    If the frequency limit is of concern, the DRV team may have an alternative device they can recommend with more margin. The true issue with the DRV8870 is its automatically enabled sleep mode. The DRV8870 needs 40us to wake-up after 1ms of inactivity. This means you will need to pad your true burst count with: 40us / (1/200kHz) = 8 additional pulses before the DRV8870 toggles the transducer. The DRV8837 allows you to manually control the sleep mode via a pin, but only allows 11V at the high-side instead of 45V as on the DRV8870. You can also implement a discrete solution of the driver as illustrated in the full bridge app note previously linked.
  • 0 in reply to Akeem Whitehead
    Intellectual 410 points
    Hi Akeem,

    Once again, thank you for the good answer. It provided a lot of useful information.

    I happen to have a spare sample of the 200LM450. So if you are willing to perform some testing and share the results, that would be great.

    Best Regards,
    Andreas