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

2.3.2 TUSS4470 220 kHz Configuration

Table 2-2 shows example starting values for short to mid range evaluation of the TUSS4470 with a 220 kHz transducer and the TUSS Gen III EVM GUI.

Table 2-2 TUSS4470 220 kHz Suggested Evaluation FW Setup
TX Setting Short Range Value Mid-Range Value RX Setting Value Output Setting Short Range Value Mid-Range Value
BURST_PULSE 4 10 BPF_HPF_FREQ 218.26 kHz ECHO_INT_
COMP_EN		 Disabled Disabled
HALF_BRG_
MODE		 Enabled Disabled LOGAMP_DIS_
LAST_GM		 Enabled Record (GUI record time) 12 ms 24 ms
Frequency 220 kHz LOGAMP_DIS_
FIRST_GM		 Enabled
Evaluation Notes:

From this starting point, tuning will almost always be required to achieve the desired VOUT output across a given ToF range. When ring down is a concern, four burst pulses was experimentally determined to serve a wide ToF range with a relatively short blind zone. When the ring down time is not important, 10 burst pulses is a good starting point. Also note that while it is recommended to start tuning with the logarithmic amplifier stages enabled for air-coupled measurements, disabling the first and last stage with LOGAMP_DIS_FIRST_GM and LOGAMP_DIS_LAST_GM can reduce errors in threshold detection since the noise floor is lower and can be more stable. However, the dynamic range will be reduced as well. In this testing, a smooth noise floor was favored over dynamic range for very short ToF or high VDRV measurements.

ECHO_INT_COMP_EN is disabled above because it is recommended that the expected VOUT is verified before enabling the echo interrupt. If the echo interrupt is desired, a threshold may be set to the necessary level with the ECHO_INT_THR_SEL bits once the device settings are adjusted for the desired VOUT.