TDC-GP21 Ultrasonic Flow Converter

TDC-GP21 Ultrasonic Flow Converter

Time-to-digital converter with integrated analog front-end.

TDC-GP21 is a 2-channel TDC with additional analog elements like extended fire-pulse generator, zero-cross detection and analog switches for simplifying the use in ultrasonic flow meter applications.

High resolution, 3-fold multi-hit capability and good pulse pair resolution make this device a good fit for industrial applications like magnetostrictive sensors, range finders or ultrasonic heat meters.
An optimized power management of the various units brings down the operating current to a few µA at 2Hz measuring rate.

TDC-GP2x Ultrasonic Flow Converter

TDC-GP21 features and benefits


  • 2-channel TDC with 22ps resolution
  • Analog frontend for ultrasonic flow meters
  • Chopper-stabilized low-offset comparator for zero crossing detection
  • Precise windowing for hit selection
  • Temperature measuring unit for PT1000 sensors
  • QFN32 package


  • High precision
  • Low power
  • Few additional external component needed

Product properties

  • Analog Frontend Yes
  • Number of hits 3
  • Resolution [ps] 22
  • Operating Supply Range 2.5 to 3.6
  • Interface SPI
  • Ambient Temperature Range [°C] -40 to +125
  • Package QFN32


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Evaluation kit

The GP21 evaluation kit is designed as a platform for a quick and easy start-up and evaluation of the TDC-GP21 Time-to-Digital Converter. The evaluation kit offers user-friendly configuration and extensive testing of the TDC-GP21.