Ultrasonic Flow Converters

AS6031 Ultrasonic Flow Converter

The AS6031 ultrasonic flow converter is based on the TDC-GP30 platform for water and heat meters.

AS6031 Ultrasonic Flow Converter for Water and Heat MetersThe transducers are driven by the same high-performance front-end, which also processes the received signal to extract the time of flight data. Weaker receive signals can be handled by adding another programmable amplifier. The split burst strengthens the initial hit level detection and makes it possible to identify and correct phase jumps.

AS6031’s excellent zero-flow drift allows for exceptional low-flow detection performance. The flow calculation can be performed by the low-power CPU using 4k of NVRAM and ROM code at a few µA current only.

The AS6031F1 comes with a flow firmware on the chip, which speeds up time to market and streamlines the design of ultrasonic water meters. It handles every aspect of ultrasonic measurement, giving users complete control over the central processor of the meter and allowing them to continue with their current platforms and software libraries.

Ultrasonic Flow Converters (UFC)


  • High performance + ultra-low power 32-Bit CPU with:
  • 120 * 32 NVRAM (non-volatile RAM) for user firmware parameter & data
  • 3968 * 8 bit NVRAM (non-volatile RAM) for user firmware program code
  • 4k * 8 ROM for system task code and special flow library code
  • Advanced high-precision analog front-end for transducer frequences of 50 kHz to 4 MHz at 2.5 V to 3.6 V drive voltage
  • Integrated PGA, gain 2 to 30 @ 1 MHz
  • First hit level and phase detection
  • Amplitude measurement
  • Up to 31 zero crossing measurements
  • Precision time-to-digital converter and low noise frontend with < 50 ps single shot with good 1MHz transducers on a DN20
  • Ultra low power consumption
  • SPI serial interface
  • General Purpose I/O unit incl. pulse interface and 2-wire master interface (I2C like)
  • Supply voltage 2.5 to 3.6 V
  • 3.0 to 3.6 V NvRAM store only
  • Operating temperature -40 to 85°C
  • QFN48 package (7x7mm²)


  • Single-chip solution provides ready flow information
  • System design compatible with meachanical meters
  • High flexibility in choice for external µP handling communication and further data management
  • Precision down to low flow rates
  • Leakage detection
  • Handles weak signals for small transducers and multiple reflections
  • Compact design
  • Low BOM


Analog Frontend
Yes, with PGA
First Wave Detection
Yes, Split burst
Amplitude Measurement
Number of Hits
Resolution TDC [ps]
Operating Supply Range
2.5 to 3.6
SPI, Pulse, 2-wire master
4k NVRAM, 4k ROM
Ambient Temperature Range [°C]
-25 to +85


  • Residential Gas Meters
  • Industrial Gas Meters
  • Clamp-on Water Meters
  • Volume Counters
Block Diagram of the AS6040 Ultrasonic Flow Converter for gas and water meters

Ordering Numbers

Type Part number Package RoHS compl. Shipping package
TDC-GP22 MNR 1949 QFN32 Yes Tray
TDC-GP22 MNR 1950 QFN32 Yes Tape & Reel (5k)
GP22-EVA-KIT MNR 1951 System Yes Box
GP22-DEMO-KIT MNR 1979 System Yes Box
TDC-GP21 MNR 1839 QFN32 Yes Tray
TDC-GP21 MNR 1720 QFN32 Yes Tape & Reel (3K/5K)
GP21-EVA-KIT MNR 1781 System Yes Box
TDC-GP2 MNR 1058 QFN32 Yes Tray
TDC-GP2 MNR 1480 QFN32 Yes Tape & Reel (2k)
TDC-GP1 MNR 278 TQFP44 Yes Tray
TDC-GPX MNR 975 TQFP100 Yes Tray
TDC-GPX-FG MNR 1089 TFBGA120 Yes Tray