onsemi RB-Series SiPM dToF LiDAR Platform (SECO-RANGEFINDER-GEVK) & App Note

Introduction : This application note provides a technical deep dive into the onsemi SECO-RANGEFINDER-GEVK, a Direct Time of Flight (dToF) LiDAR development platform. By utilizing high gain Silicon Photomultipliers (SiPM), this platform overcomes the limitations of traditional PIN and APD sensors, offering a robust solution for industrial distance measurement.

Features of LiDAR Platform

It is built around the RB-series SiPM, which is specifically enhanced for Near Infrared (NIR) sensitivity at 905 nm.

• Measurement Range : 0.11 m to 23 m
• Wavelength : 905 nm (NIR)
• Safety : Class 1 Laser Product (BS EN 60825-1:2014)
• Precision : Provided by an FPGA based Time to Digital Converter (TDC)

Transmit Chain : Precision Pulse Generation

The main function of transmit part is to fire ultra short and high power pulses of light towards target and start the timer. Following are the different modules used in this transmit chain.

• Pulse triggering : FPGA such as Lattice iCE40 is used to generate digital trigger pulse.
• Laser driver : It provides enough current to rapidly switch logic level MOSFET which controls laser diode.
• Emitter : It is laser diode (usually 905 nm) that converts electrical pulse into optical one.
• Reference Signal (START Pulse) : To ensure timing accuracy, a portion of the light is captured locally by a reference diode co-located with the laser. This signal passes through a discriminator (such as nsemi NBA3N012C) to create a precise START pulse for the TDC. This cancels out any internal delay caused by the driver electronics.

Receive Chain : Extracting Signals from Noise

The main goal of receiver is to capture returning photons that are bounced off from far-away target, often in the presence of sunlight. Following are the modules used in receive chain.

• Optical filtering : Light passes through Band Pass Filter of wavelength 905 nm before it reaches the sensor. This blocks most of the ambient solar noise.
• Detector : Onsemi RB-Series SiPM is used as sensor. Each SiPM consists of thousands of microcells. When a photon hits a cell, it triggers a Geiger avalanche, resulting in a massive gain.
• Signal conditioning : The weak current from the SiPM is amplified and then passed through an RF transistor and a discriminator.
• STOP Pulse : Once a return signal exceeds the pre-set threshold, the discriminator generates a STOP pulse, which is sent to the FPGA.

Advanced Signal Processing: In industrial environments, a single return pulse is often lost in background noise (SNR issues). The onsemi platform uses a Multi shot approach handled by the FPGA.

Summary

• By integrating onsemi’s high performance NIR components with a flexible FPGA based timing system, developers can bypass months of optical engineering and move straight to solving real world challenges in robotics, logistics and industrial sensing.
• The SECO-RANGEFINDER-GEVK is an essential evaluation tool because it provides the full BOM (Bill of Materials), schematics, and Gerber files needed for mass deployment. Visit onsemi.com for more information.