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PGA460-Q1: Detection Range, two transducer switching

Guru 20090 points
Part Number: PGA460-Q1
Other Parts Discussed in Thread: PGA460

Hello,

Our customer would like to use the device for detection range from 10cm to 8m.
In the datasheet P.106 there is the description that "The lower frequency range of 30 to 80 kHz is the default operating range for common automotive and consumer applications for a step resolution of 1 cm and typical range of 30 cm to 5m.".

Can we use PGA460-Q1 for this range?

If yes, could you please let me know the reference condition for detect this range?
Is this depend on transducer specification?
If the device has any function for expand detection range, please let me know.

Best Regards,
Ryuji

  • Ryuji,
    The detectable range is dependent on several factors:
    1) Transducer topology: mono-static or bi-static. Mono-static is a single transducer that both sends and receives, while bi-static is two transducers where one is dedicated to transmitting, and the other dedicated to receiving.
    2) Transducer type: closed-top or open-top. Closed-top protect from water/dirt, while open-tops have more sensitive receivers that don't require large excitation voltages.
    3) Drive mode: transformer or direct-drive. Transformer mode is used to excited closed-tops up to +100V peak-to-peak, while direct-drive (bridge drive) is more ideal for open-tops requiring an excitation voltage up to 30V.
    4) Target type: size, shape, and surface material of target. A flat metal surface is easier to detect than a narrow carpeted pole.
    5) Transducer frequency: low (30-80kHz) or high (180-480kHz). Low freq transducer are more general purpose, while high-freq transducers are typically limited to short-range only applications that require high resolution.
    6) Transducer field-of-view: It is important to consider that many transducers have a wide area coverage FOV. Side-lobe reflections from unintended targets may results in false positives. Low-frequency trasnduers tend to have wide beam angles, but this can be constrained with the use of a horn (see FAQ www.ti.com/.../slaa733).

    Have the customer review these factors and others in more detail by reading the PGA460 Ultrasonic Module Hardware and Software Optimization (www.ti.com/.../slaa732) appnote. Once the customer has a better understanding of the different operating modes, have them propose their preferred transducer topology, transducer type, drive mode, and target types for us to better recommend and give feasibility.

    What is the customers use-case?

    If the customer has no preference, I would recommend a bi-static open-top transducer pair (such as the Murata MA40S4S/R pair) driven in a half-bridge driver mode. This will enable the best case min and max ranging at a low cost and small solution size. This configuration can achieve sub-10cm at the minimum range, and beyond +10m when targeting a wall. Smaller targets may yield a shorter maximum range.

    See the PGA460 Bi-static Transducer Half-Bridge Driver Small Form Factor Design File (www.ti.com/.../slac760) for an example of the solution size.