SNAS648C October   2014  – February 2023 TDC1000

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information (1)
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Transmitter Signal Path
      2. 8.3.2 Receiver Signal Path
      3. 8.3.3 Low Noise Amplifier (LNA)
      4. 8.3.4 Programmable Gain Amplifier (PGA)
      5. 8.3.5 Receiver Filters
      6. 8.3.6 Comparators for STOP Pulse Generation
        1. 8.3.6.1 Threshold Detector and DAC
        2. 8.3.6.2 Zero-Cross Detect Comparator
        3. 8.3.6.3 Event Manager
      7. 8.3.7 Common-Mode Buffer (VCOM)
      8. 8.3.8 Temperature Sensor
        1. 8.3.8.1 Temperature Measurement With Multiple RTDs
        2. 8.3.8.2 Temperature Measurement With a Single RTD
    4. 8.4 Device Functional Modes
      1. 8.4.1 Time-of-Flight Measurement Mode
        1. 8.4.1.1 Mode 0
        2. 8.4.1.2 Mode 1
        3. 8.4.1.3 Mode 2
      2. 8.4.2 State Machine
      3. 8.4.3 TRANSMIT Operation
        1. 8.4.3.1 Transmission Pulse Count
        2. 8.4.3.2 TX 180° Pulse Shift
        3. 8.4.3.3 Transmitter Damping
      4. 8.4.4 RECEIVE Operation
        1. 8.4.4.1 Single Echo Receive Mode
        2. 8.4.4.2 Multiple Echo Receive Mode
      5. 8.4.5 Timing
        1. 8.4.5.1 Timing Control and Frequency Scaling (CLKIN)
        2. 8.4.5.2 TX/RX Measurement Sequencing and Timing
      6. 8.4.6 Time-of-Flight (TOF) Control
        1. 8.4.6.1 Short TOF Measurement
        2. 8.4.6.2 Standard TOF Measurement
        3. 8.4.6.3 Standard TOF Measurement With Power Blanking
        4. 8.4.6.4 Common-Mode Reference Settling Time
        5. 8.4.6.5 TOF Measurement Interval
      7. 8.4.7 Averaging and Channel Selection
      8. 8.4.8 Error Reporting
    5. 8.5 Programming
      1. 8.5.1 Serial Peripheral Interface (SPI)
        1. 8.5.1.1 Chip Select Bar (CSB)
        2. 8.5.1.2 Serial Clock (SCLK)
        3. 8.5.1.3 Serial Data Input (SDI)
        4. 8.5.1.4 Serial Data Output (SDO)
    6. 8.6 Register Maps
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Level and Fluid Identification Measurements
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Level Measurements
          2. 9.2.1.2.2 Fluid Identification
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Water Flow Metering
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Regulations and Accuracy
          2. 9.2.2.2.2 Transit-Time in Ultrasonic Flow Meters
          3. 9.2.2.2.3 ΔTOF Accuracy Requirement Calculation
          4. 9.2.2.2.4 Operation
        3. 9.2.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

8.4.4.2 Multiple Echo Receive Mode

The Multiple Echo mode is intended for use in level sensing applications and distance/displacement measurements in which multiple echoes (burst) are received. In this condition, each received echo group will be treated as a single pulse on the STOP pin. Up to 7 STOP pulses can be generated based on the value of the NUM_RX field in the CONFIG_1 register. Multi echo mode can be enabled by setting the RECEIVE_MODE bit to 1 in the CONFIG_4 register. #SNAS6484660 shows a representation of multiple echo STOP pulse generation.

GUID-3CFB3B3E-5405-48AF-9F51-AE4D90FAAC01-low.gifFigure 8-20 Multiple Echo Receive Mode (5 STOP Events)

The rising edge of a STOP pulse is generated by a zero-crossing event. As in the Single Echo Receive Mode, the threshold comparator qualifies the next zero-cross after an RX amplitude smaller than the programmed threshold voltage is detected. The STOP pulse will extend until a zero-cross after the RX amplitude is no longer smaller than the threshold voltage (see #SNAS6488072).

GUID-3A7F0B27-9C22-41EA-A59E-949DF02ADECD-low.gifFigure 8-21 Multiple Echo Receive Mode (Zoom-in)

If the number of expected pulses programmed in NUM_RX is not received or the time-of-flight operation times out, the TDC1000 will indicate an error condition in the ERROR_FLAGS register and will set the ERRB pin low.