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TDC-GP21 Ultrasonic Flow Converter

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


  • 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 parameters

Analog Frontend Yes
First Wave Detection -
Amplitude Measurement -
Number of Hits 3
Resolution [ps] 22
Operating Supply Range 2.5 to 3.6
Interface SPI
Firmware -
Memory -
Ambient Temperature Range [°C] -40 to +125
Package QFN32

General Description

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. An optimized power managements of the various units brings down the operating current to a few µA at 2Hz measuring rate.

This product suits for the following applications:

  • Ultrasonic heat meters
  • Ultrasonic gas meters
  • Ultrasonic flow indicators
  • Laser rangefinders
  • Magnetostrictive sensors


Title Category Headline Buy
TDC-GP21EvalKit Application Board Evaluation Kit for TDC-GP21
TDC-GP22DemoKit Application Board Demo Kit for TDC-GP22
TDC-GP22EvalKit Application Board Evaluation Kit for TDC-GP22

Technical Documents

Type Description Language
Datasheet Document version 1.6 English
Datasheet Document version 1.6 English

Environmental Documents

Type Description Language
RoHS Certificate RoHS Certificate_TDC-GP21 English


Type Description Language
EoL Notification TDC-TCN1 (issued 2017-Apr) English
Product Change Notification Change Notification_MOQ Amendment_PCAPx_TDC-GPx_PS09FN (issued 2017-Mar) English
Product Change Notification CN13-2017 (PCAP0x, TDC-GPxx, PS09) English

Other Information

Type Description Language
Block Diagram TDC-GP21 Block Diagram English

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