Time to Digital Converters

TDC-GP2 – Time to Digital CONVERTERS

TDC with Special Features for Ultrasonic Flow Meters and Ultrasonic Heat Meters

The TDC-GP2 is an ScioSense (previously acam) general-purpose Time to Digital Converter (TDC). Higher resolution and smaller package size make it ideal for cost-sensitive industrial applications. With single shot resolution of 22ps and a 4 ms measurement range, the TDC-GP22 has the resolution and timing range for many applications that require precise measurement, while still being a low cost part. With special function blocks like a fire pulse generator, stop enable, temperature measurement, and clock control, it is perfectly suited for flowmeter and heat-meter applications.

TDC-GP2 is not recommended for new design.


Time to Digital Converters


Measurement Range 1

  • 2 channels with typ. 50 ps rms resolution
  • 65 ps Bin size
  • Measurement range 3.5 ns to 1.8 µs
  • 15 ns pulse-pair resolution with 4-fold multihit capability
  • 4 events can be measured arbitrarily against each other
  • Windowing for precise stop enable

Measurement Range 2

  • 1 channel with typ. 50 ps rms resolution
  • 65 ps Bin size
  • Measurement range 500 ns to 4 ms
  • 2 x CLKHS pulse-pair resolution with 3-fold multihit capability
  • Each of the 3 events can be assigned to an adjust-able measuring window with 10ns resolution

Special Features

  • Fire pulse generator for up to 15 pulses with programmable phase
  • 4 temperature measurement ports for 16 Bit temperature measurement
  • Clock calibration unit
  • Typical current consumption 5 µA

General Features

  • Trigger to rising and/or falling edge
  • I/O voltage 1.8 V to 5.5 V
  • Core voltage 1.8 V to 3.6 V
  • 1 MHz continuous data rate max.
  • Temperature range 40°C to 125°C
  • 4 wire SPI interface
  • QFN 32 package


TDC-GP2 Temperature Measurement

Especially for heatmeter applications the TDC-GP2 has a PICOSTRAIN based temperature measuring unit that offers high resolution and very low current consumption.

The unit has 4 resistor ports with the following function:

  • PT1: reference resistor lower temperature
  • PT2: sense resistor lower temperature
  • PT3: sense resistor lower temperature
  • PT4: reference resistor higher temperature

The temperature sensor should have a minimum resistance of 500 Ω (PT500/1000);. The TDC-GP2 measures the discharge times of the RC-networks made of each resistor and the capacitor.

The precision of the temperature measurement is about 0.004°C which is 5 times better than needed. When measuring every 30 seconds the current consumption is 0.08 µA only.

The temperature measurement is fully automated. It is triggered by the µC sending the opcode “Start_Temp”. The TDC-GP2 controls the 4 measurements by itself. After the 4 measurements have finished the interrupt flag is set. The four data are found in registers 0 to 3.

From Res_2/RES_1 and RES_3/RES_4 the microcontroller can calculate the ratio Rtemp/Rref. By means of a look-up table it can calculate the temperature for the special type of sensor in use.

It is not possible with TDC-GP2 to use 4-wire temperature sensors.


Current Consumption

By means of the PICOSTRAIN technology the temperature measurement needs an extremely low current, much less than an A/D converter does.

A full temperature measurement with 2 sensors, 2 references, including all calculations takes less than 2.5 µAs. With one temperature measurement in 30 seconds (typical for heatmeters) the average current consumption is 0.08 µA only. This is about 50 times less than other solutions.

TDC-GP2 Fire-pulse Generator

The fire-pulse generator generates a sequence of pulses which is highly programmable in frequency, phase and number of pulses. The high-speed oscillator frequency is used as the basic frequency. This frequency is internally doubled and can freely be divided by a factor of 2 to 15. It is possible to generate 1 to 15 pulses. For each pulse the phase can be adjusted per register configuration.

The fire-pulse generator provides 2 outputs. The driver strength of each output is 48 mA @ 5V. These 2 outputs can be paralleled to increase the driver strength up to 96 mA. Furthermore each output signal can be inverted to double the signal amplitude. The outputs can be set individually high-Z.

The fire-pulse generator allows to generate and send pulse sequences multiple times for use in a quasi sing-around method. Using this feature the received pulse sequence is fed into TDC-GP2 Fire_In input. It is digitally amplified and directly forwarded to the output buffer for an immediate re-emittance without any clock delay.

Block Diagram


Package Outline


Documentation & Downloads

Ordering Numbers

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