TUSS4470: TUSS4470

Hello Michael,

Thanks for posting to the sensors forum! I see that you posted another thread here: https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/1392061/tuss4470-tuss4470

I'll be answering both your threads on this post.

Questions from previous thread:

1. Is it possible to measure distances less than 1m using this chip and senor 40kHz?
   1. When using a monostatic solution, the minimum sensing distance is mostly based on the transducer frequency, the voltage the transducer is being driven with, and the amount of pulses being transmitted out of the transducer. You should be able to achieve less than 1m with a 40kHz transducer but you might need to reduce the number of pulses being emitted for the lower ranges.
2. The analog signal on Vout has a significant duration due to transient processes. How to solve this problem? 
   1. Another option is to use a bistatic solution which requires a separate TX and RX transducer and two separate devices. You can achieve a pseudo bistatic solution with the TUSS4470 by using two transducers an a single TUSS4470 device. There is still some internal noise that would couple to the AFE return path but this helps reduce the blind zone significantly.
3. Specify the sensor you used in the tests?
   1. The sensor used was a Murata MA300D1-1

I hope this helps!

Best,

Isaac

Hello Isaac,

What configuration should I choose to provide measurement in the range from 50mm to 2000mm using TUSS4470. Maybe it is not suitable for this task. What would you recommend? Maybe another TI chip?

Please give your assessment of the configuration that I use for a 300kHz sensor and an external voltage of 20v

I would like to draw your attention to the fact that the setting of the comparator level for determining the distance depends on the distance itself.

The receive channel has too much delay and this affects the minimum distance measurement.

This case you can see below:

I'd also like to point out that the amplitudes I'm getting are much smaller than I see in the datasheet.

Hello Michael,

The device can definitely handle the upper portion of this range, but may struggle on the lower end, mainly due to a limitation of ultrasonic technology in general. To get the lower portion you may need to use a bistatic implementation which employs the use of two separate transducers one for transmission and one for receiving in general. The reason this is needed is due to the ringing time of the transducer so the voltage decays slowly after transmission meaning that the input of the transducer is saturated during that time unable to receive signals. Having more pulses and larger voltage also makes the lower end of the measurement much more difficult. 

For the long distance sensing range I believe the main problem may be in the chosen transducer frequency, higher frequencies will attenuate much quicker than a lower frequency, meaning that the ringing period will be decreased but the signals themselves also don't carry as much energy meaning they would decay much faster. So in order to get to increase the range you so you may require more voltage if you decide to continue pursuing the 300kHz transducer or you can also decrease the transducer frequency and remain at the same voltage and identify if the result is closer than before.

Here is a capture of 40kHz transducer at 5V measuring ~2.4m, if you notice the  ringing period is significantly longer than the 300kHz due to the lower frequency.

The amplitudes in the datasheet may differ depending on the target that is being used. A larger target will have a larger surface area to return more signal at the transducer or a different target material can have a different acoustic impedance that absorbs more of the signal instead of reflecting it.

Best,

Isaac