eToF™ Laser Driver ICs for Advanced Autonomy Lidar
Mar 22, 2021
Co-written by Steve Colino
Laser drivers for light distancing and ranging (lidar) are used in a pulsed-power mode. What are the basic requirements for these laser drivers?
- High current
- High speed
- Small size
- Low cost
A new family of integrated laser driver ICs meets all these requirements. The first release, the EPC21601 laser driver IC, integrates a 40 V, 10 A FET with integrated gate driver and 3.3 V logic level input in a single chip for time-of-flight (ToF) lidar systems used in robotics, surveillance systems, drones, autonomous cars, and vacuum cleaners. This chip offers frequency capability up to 200 MHz in a low inductance, economical, 1 mm x 1.5 mm BGA package.
The EPC21601 IC runs off a 5 V supply to power the logic. The IC requires just one bypass cap for the 5 V supply and a logic level input. The waveforms below show the IC switching 10 A through a 2-ohm resistive load at just under 20 MHz. The rise and fall times are 300 to 400 picoseconds, and they are very clean.
To demonstrate the frequency capability, the device was pushed beyond the spec limit to see where they would break. The below waveform is at room temperature, and you can see that the waveforms are becoming a little distorted. The device is operating way out of spec, but it is still working. Even 200 MHz operation is not enough to break it!
For a straightforward evaluation of the EPC21601, the EPC9154 demonstration board uses best-practice layout and high-frequency measurement techniques, achieving 410 ps turn-on and 320 ps turn-off from 20 V with a 10 A resistive load. The demos come with an interposer board for mounting your choice of VCSEL or edge-emitting laser.
The EPC21601 is the first offering in what will be a wide-ranging family of integrated laser drive ICs available in chip-scale packages (CSPs). The next will be the EPC21603, which has the same ratings as the EPC21601 but offers a low voltage differential signal (LVDS) input for ToF applications where noise immunity is critical, such as augmented reality.
Integrated devices in a single chip are easier to design, easier to layout, easier to assemble, save space on the PCB, increase efficiency, and reduce cost. This family of products will enable faster adoption and increased ubiquity of ToF solutions across a more comprehensive array of end-user applications.