New high-speed, 20ps time-to-digital converter

The new LTDC-X3 TDC is ideal for use in optical ranging systems in robots, drones, golf range finders, safety scanners, and many other industrial applications.

The launch of the LTDC-X3 builds on ScioSense’s position in the general market for TDCs, which it has established through its products’ high accuracy and precision, and their easy integration into a host system.

The new TDC, which offers single-shot resolution of up to 20psrms, can measure both the rising and falling edge of a pulse on both Stop channels. To meet LiDAR systems’ requirement for a high sampling rate, ScioSense has equipped the LTDC-X3 with a high-speed quad SPI interface transferring output data at a rate of up to 50MHz or 200MB/s. The device can operate with an interval between pulses of as little as 5ns.

The LTDC-X3 can also be configured to register up to four Stop triggers for each Start pulse, enabling a LiDAR sensor to detect reflections from multiple objects in the field of view. By taking advantage of the combination of ultra-high precision and multiple Stop triggers, a LiDAR system can generate a detailed and accurate picture of the complex environment through which a drone or robot might navigate.

As well as providing the core time measurement function, the LTDC-X3 operates as an integrated sensor interface, providing important features such as:

• Start pulse generator with configurable phase noise, for trigger signals to an external laser diode driver
• Stop input comparator compatible with an LVDS interface
• On-chip calculation of Stop-Start time differences and the Stop pulse width

Norbert Breyer, Director of Marketing and Product Management at ScioSense, said: “Many industrial LiDAR systems today continue to rely on an FPGA to provide the interface to a laser diode emitter and detector – a solution which occupies a large board footprint, consumes a lot of power, and is expensive. The introduction of the LTDC-X3 gives LiDAR system manufacturers a new, smaller option which offers higher speed, consumes much less power and has an attractive unit cost.”

Integrated time measurement capability

The LTDC-X3 implements a dedicated measurement sequence, starting with initialisation, waiting for hits on the Start and Stop inputs, and ending with the interrupt when all hits or a timeout are detected. LVDS inputs enable easy integration into the host system’s fast analog front end.

The LTDC-X3 is supplied in a compact 32- QFN package with a footprint of just 4 x 4mm.

Low power dissipation of just 150mW eases thermal design.