Time to digital converter measures distance down to 4cm

17th January 2017

Mick Elliott

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Datasheet

The TDC7201 time-to-digital converter from Texas Instruments is now being shipped by Mouser Electronics. The converter is designed for use with ultrasonic, laser, and radar range finding equipment using time-of-flight (TOF) technique. Laser-based TOF applications demand picosecond accuracy plus the ability to measure very short durations.

Two built-in time-to-digital converters (TDCs) enable the device to be used to measure distance down to 4cm and up to several kilometres using a simple architecture, which eliminates the need to use FPGAs or processors.

Each TDC performs the function of a stopwatch and measures the TOF between a START pulse and up to five STOP pulses.

This ability to measure simultaneously and individually on two pairs of pins using two built-in TDCs offers high flexibility in time measurement design.

The TDC7201 features a wide measurement range of 0.25ns to 8ms and high accuracy of 28ps. The device has a single shot resolution of 55ps, (equivalent to 0.825cm).

When placed in the autonomous multi-cycle averaging mode, the TDC7201 device can be optimised for low system power consumption, which is ideal for battery-powered flow meters.

In this mode, the host can go to sleep to save power and wake up when interrupted by the TDC upon completion of the measurement sequence.

The TDC7201 is supported by the TDC7201-ZAX-EVM evaluation module, also available from Mouser. This is a BoosterPack plug-in module for the MSP430F5529 LaunchPad and includes two pairs of SMA connectors for START and STOP inputs plus a user-friendly graphic user interface (GUI) to modify the registers, display time of flight, and export data in CSV format.

The TDC7201 is ideal for TOF laser-range-finding applications, including surveying, navigation, drones, and robotics, as well as collision avoidance in autonomous vehicles.