Time-To-Digital Converters Emerge as Key Components in Autonomous Vehicles

A Look Inside Time-to-Digital Converter Applications

Water Flowmeters

Water flowmeters include two sound transducers, “A” and “B,” as in the picture below. Either can be used to transmit or detect a sound pulse.


Water Flowmeter. Image source: Maxim integrated


First “A” transmits, and “B” receives, with an appropriately configured time-to-digital converter recording the time between transmission and reception. Then, the sequence is reversed, with “B” transmitting and “A” receiving. This time interval, too, is captured by the time-to-digital converter.

It may seem that the times would be equal, as the sounds are traveling the same distance, but it isn’t so. The sound is moving through the water, but the water itself is traveling. So the sound going against the flow is slowed down, and the sound going with the flow is sped up.

The time periods are both noted, and by observing which time is longer and which is shorter, the device easily determines the direction of water flow. Additional knowledge of factors, such as the water pipe’s diameter, allows simple calculation of the volume of water flow.

Smart Cars

LIDAR stands for Light Detection and Ranging. It is a key component in smart cars, because it can warn the driver, or an autonomous controller, when a vehicle is getting too close to an object such as a barrier or to another vehicle.

Lidar works by emitting a laser pulse, and noting the arrival of the same pulse when it returns to the source.

Here, too, the time is noted by the time-to-digital converter. The speed of the pulse is the speed of light. With time and velocity known, the device can easily compute the distance between objects.