Time to Digital Converter basics | Time to Digital Converter ICs
This page on time to digital converter describes basics of time to digital conversion with application notes on popular Time to Digital Converter ICs available from semiconductor manufacturers.
In digital signal processing and electronics domain, these converters are used to recognize time interval between two events (say 'START' and 'STOP') and also to measure time in digital formats.
What is Time to Digital Converter ?
The device which converts time interval to measurable digital or binary format is known as time to digital converter. The common implementations of the time to digital conversion include counter which increments or decrements on every clock cycle. Usually this converter employs crystal to achieve long term stability in the output. The counter measurement technique is used for coarse measurement. The other fine measurement techniques are ramp interpolator, vernier method and tapped delay line. The hybrid method for time to digital conversion measurement offers long interval measurement with high resolution.
There are wide applications of time to digital converters which include flow meter (for water, gas and heat meter measurements), magnetostrictive sensor (for position/level sensing), time of flight in drones as well as metering equipments and projectors.
Image Courtesy: Texas Instruments Incorporated
The figure depicts TDC7200 from TI which can be used as time to digital converter. This TI IC performs function of stop watch which measures elapsed time (i.e. TOF or Time of Flight) between START and upto five STOP pulses.
Time to Digital Converter ICs
Following table mentions silent features of time to digital converter ICs from popular semiconductor manufacturers.
| IC Manufacturers | Part Number | Description of features |
|---|---|---|
| Texas Instruments Incorporated | TDC7200 | • Measurement Range: Mode-1: 12 ns to 500 ns and Mode-2: 250 ns to 8 ms • Data output (DOUT) format: SPI • Data In (DIN) pin is provided. This pin is driven by SPI master by transmitting command and data byte to configure the IC. • Standard deviation : 35 ps • Resolution : 55 ps • Supply : 2V to 3.6V |
| Maxim Integrated | MAX35101, MAX35102 | • The IC MAX35101 offers time measurement accuracy of about 20ps, measurement range upto 8 ms, 4 wire SPI interface etc. • The IC MAX35102 is similar to MAX35101 but with reduced features. Moreover it does not house RTC (real time clock). |
| Integrated Device Technology, Inc. | ClockMatrixTM TDC | • This family based devices can be used for speeds upto 100 Gbps interface. • They are used for various functions such as clock generation, jitter attenuation, frequency translation and phase alignment. • The common programmable interfaces supported are SPI or OTP and I2C. |
| ams AG | AS6500, AS6501, TDC-GPX, TDC-GPX2 | • AS56500 time to digital converter IC supports 4 stop channels with 20ns pulse to pulse spacing. • It offers maximum speed of about 1.5 MSPS via SPI interface. • It offers unlimited measuring range from 0 to 16 seconds. • Resolution of about 20 ps can be achieved. • Check https://ams.com/ for more information on other time to digital converter ICs offered by AMS. |
| LeCroy Corporation | MTD135, MTD133B | • They are 8-Channel, Multi-hit Time-to-Digital Converter ICs manufactured by LeCroy Corporation. |
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