SLDA058 March   2021 TUSS4470

 

  1.   Trademarks
  2. 1Review of Ultrasonic Sensing Range Performance Factors
    1. 1.1 Physical Parameters
    2. 1.2 Transducer Characteristics
    3. 1.3 AFE Device Configuration
  3. 2Methods Overview
    1. 2.1 Introduction
    2. 2.2 Hardware Configuration
      1. 2.2.1 Transducers
      2. 2.2.2 Experimental Setup: Air-Coupled Level Sensing
      3. 2.2.3 Experimental Setup: Water-Coupled Level Sensing
      4. 2.2.4 TUSS4470 EVM Hardware Configuration
      5. 2.2.5 TDC1000-C2000EVM Hardware Configuration
    3. 2.3 Firmware Configuration
      1. 2.3.1 TUSS4470 Power Configuration
      2. 2.3.2 TUSS4470 220 kHz Configuration
      3. 2.3.3 TDC1000 220kHz Configuration
      4. 2.3.4 TDC1000 220kHz Configuration
      5. 2.3.5 TDC1000 1 MHz
  4. 3Short Range Air-Coupled Test Results
    1. 3.1 TUSS4470
    2. 3.2 TDC1000
  5. 4Mid-Range Air-Coupled Test Results
    1. 4.1 TUSS4470
      1. 4.1.1 Concept
      2. 4.1.2 TUSS4470 35 V Results
    2. 4.2 TDC1000
  6. 5Short Range Water-Coupled Test Results
    1. 5.1 TUSS4470
    2. 5.2 TDC1000
  7. 6Resistive Damping Device Comparison
    1. 6.1 TUSS4470
    2. 6.2 TDC1000
  8. 7Summary
  9. 8References
  10.   A Appendix A
    1.     A.1 TUSS4470: Filter Capacitor Selection
    2.     A.2 TUSS4470: Shematic
  11.   B Appendix B
    1.     B.1 TDC1000 Misc.
    2.     B.2 TDC1000-C2000EVM Schematic

6.1 TUSS4470

Figure 6-1 shows the TUSS4470 VOUT signal: undamped, 500Ω damped, and 75Ω damped, respectively. Cursors show the distance between the TX pulse and the first return echo pulse. To quantify the damping effect, cursor 'a' is placed to cross VOUT on the TX pulse approximately at the voltage level bisecting min and max of the leading edge of the first return pulse. Another helpful measure could be taken from the start of the TX decay until the first rising edge.

GUID-20210310-CA0I-ZTLD-06MB-MZN9MMZWTXDP-low.png Figure 6-1 TUSS4470 1MHz Water Level Measurement: Undamped

Figure 6-2 shows a 10 kΩ potentiometer soldered in parallel to the transducer across J3 on the TUSS4470EVM provided the adjustable damping resistance.

GUID-20210310-CA0I-1WGB-MJ3K-PBTHH8QXLG4H-low.png Figure 6-2 TUSS4470 1 MHz Water Level Measurement: 500Ω damping

Figure 6-3 compares the constant ToF measurements, the damped measurements show a quicker decay before the first echo pulse arrives as the resistance is decreased. The timing metric used here also increases from 75.2 μs to 93.2 μs, illustrating that the minimum range will be somewhat improved with resistive damping. The drawbacks to resistive damping are reduced range or increased current consumption from the increased load on the transducer driver.

GUID-20210310-CA0I-KF5Z-BNNN-J3Z8XGPJHTBP-low.png Figure 6-3 TUSS4470 1 MHz Water Level Measurement: 75Ω damping