PGA460: How to Detect Short Distacnce

Hi Kato,
It is very difficult to use nearly any low-frequency (30-80kHz) transducer in a mono-static (single transducer) configuration for sub-10cm object detection. The ring-decay time of the transducer is typically too long to enable very short range detection. Here is a list of alternative transducers you can use: e2e.ti.com/.../620399

I typically recommend to use a high-frequency (180-480kHz) transducer for sub-10cm object detection in a mono-static transducer. Otherwise, you will need to use a bi-static configuration to continue using a low-freq transducer such as the MA40H1S-R. This means you will need to use two MA40H1S-R transducers: one dedicated to transmitting, and the other dedicated to receiving.

There are a few optimization techniques you can implement to try to reduce the ring-decay time. This first you can do for the MA40H1S-R is reduce the high-side voltage for the bridge driver to 1~5V. On the BOOSTXL-PGA460, the daughtercard currently attaches to VPWR to force the high-side voltage of the bridge driver to the same voltage. You can selectively connect the BOOSTXL-PGA460 motherboard to the daughtercard to connect the voltage pin of the daughtercard to an external voltage. Other modifications are described in the "PGA460 Ultrasonic Module Hardware and Software Optimization" appnote ( www.ti.com/.../slaa732 ), although the default damping resistor is relatively well-matched on the BOOSTXL-PGA460 daughtercard.