SLAA907D September   2019  – December 2021 PGA450-Q1 , PGA460 , PGA460-Q1 , TDC1000 , TDC1000-Q1 , TDC1011 , TDC1011-Q1 , TUSS4440 , TUSS4470

 

  1.   Trademarks
  2. 1What is Ultrasonic Time-of-Flight Sensing?
    1. 1.1 Principles of Ultrasound
    2. 1.2 Why Use Ultrasonic Sensing?
    3. 1.3 How Does Ultrasound Compare to Other Sensing Technologies?
    4. 1.4 Typical Ultrasonic-Sensing Applications
  3. 2Ultrasonic System Considerations
    1. 2.1 Introduction to the Ultrasonic System
    2. 2.2 The Ultrasonic Echo and Signal Processing
    3. 2.3 Transducer Types
    4. 2.4 Transducer Topologies
    5. 2.5 Transducer Frequencies
    6. 2.6 Transducer Drive (Transformer Drive & Direct Drive) and Current Limit
    7. 2.7 Pulse Count
    8. 2.8 Minimum Detection Range
  4. 3What Factors Influence Ultrasonic Sensing?
    1. 3.1 Transmission Medium
    2. 3.2 Acoustic Impedance
    3. 3.3 Radar Cross Section
    4. 3.4 Ambient Conditions (Temperature, Humidity, Debris)
    5. 3.5 Device Selection
  5. 4Additional Resources
  6. 5Revision History

2.6 Transducer Drive (Transformer Drive & Direct Drive) and Current Limit

There are two ways to drive a transducer: in transformer mode or in direct drive mode. This is determined based on the maximum drive voltage (thus a higher current limit) of the selected transducer. Although direct drive is the lower-cost driving technique, it is typically intended for short range, open-top applications. Transformer drive maximizes closed-top transducer requirements (beyond 100 Vpp), but it also requires additional calibration at mass production. Figure 2-9 shows the non-linear relationship between transducer (XDCR) drive voltage, and the percent of the sound pressure level that is transmitted. Note that blindspot lengths increase with higher current limits.

GUID-C6A7121B-04D1-4FF8-B640-68073B1A6354-low.pngFigure 2-9 SPL Across Driving Voltage