The story I’m going to tell today is about a very small part that plays a very big role in a large machine. This part is so small that almost a dozen could fit on a dime. The part provides the function of a DC/DC switching regulator. The large machine in which it plays an over-sized role is the autonomous vehicle.
Soon automobiles will drive themselves. Those automobiles will have electronic eyes, and these eyes need reliable power, power that must be sourced by energy efficient power supplies. One of the key technologies behind these electronic eyes is called LiDAR, short for “Light Detection And Ranging.” LiDAR uses laser pulses to feed a digital processor which builds 3D objects and determines distance and speed. It is at the core of many state-of-the-art automotive safety systems performing important tasks such as lane detection and automatic braking. LiDAR sensors also offer a wide field of view (FoV), and perform well in bright sunlight and at night, complementing existing radar and camera vision system shortfalls.
Because car batteries provide just a single voltage and LiDAR (as well as other car systems) needs many different voltages (sometimes up to +/-250 volts and beyond), switching regulators are critical to providing the regulated voltages required for LiDAR operation. The switching regulator must respond to changes in voltage going into it and provide a consistent voltage at its output. Too little voltage and the system may not function, too much and circuit damage could occur. Neither would be good for driver or passenger safety, not to mention the unwanted trip to the auto service department. It’s a kind of like Goldilocks’ porridge problem - LIDAR systems need controllable voltages that are “just right.” Analog Devices’ new LT8365 is a micropower boost switching regulator designed specifically to deliver exactly the right voltage in the smallest solution footprint.
LiDAR systems often need their controllable voltage to be negative – which is key to the operation of an element in the LiDAR system. Yes, voltage can be positive or negative. Many of us learn the lesson when we accidentally install a battery the wrong way and the device doesn’t work. Also, the voltage from the typical electrical outlet in most countries alternates between positive and negative. This “swing” between positive and negative provides more overall power. This becomes important to high performance LiDAR.
Common batteries have positive and negative sides
Okay, so earlier I wrote how LIDAR bounces light off objects to determine how far away and how fast they are moving. Detecting the reflected light is a photodiode, an electronic component which converts light into electricity. LIDAR requires an extremely sensitive type of photodiode called an Avalanche Photodiode, or APD. Avalanche describes the behavior of the diode under certain conditions (engineers can be very descriptive). The use of larger voltages (both negative and positive) increases the photodiode’s sensitivity, enabling a more accurate and safer LIDAR system.
Analog Devices’ LT8365 has a power switch voltage rating (150V) that is twice the voltage of the nearest competing part. This enables the smallest solution on the market because competitive solutions require extra, external components to achieve the same output voltage. The LT8365-based switching regulator is also less complex than competing solutions, which may seem contradictory because the LT8365 does so much more than others can in such a small space.
So why all this fuss about a tiny part inside a big automobile? Because consumers want more and more features in their cars, such as collision avoidance and voice recognition for hands-free dialing. More devices add weight and circuit complexity while automobile and other vehicle manufacturers are endeavoring to make lighter, more energy efficient, and reliable cars. The LT8365-based Switching Regulator boosts a customer’s ability to reduce size, complexity and power draw for a critical component in today’s modern vehicle.