Updated August 2019
We’ve all heard the headlines lately about efforts going into developing and testing a new generation of autonomous vehicles. Developing advanced driver assistance systems (ADAS) is an important trend in the automotive industry to make driving safer and pave the way to autonomous driving. This push toward increased driver assistance and automation relies on a variety of different sensors designed into the cars of tomorrow, such as cameras, radar or LIDAR.
Camera modules, in particular, will provide critical data for the autonomous decision-making process, such as reading road signs; thus, the requirements on car vision systems are rapidly evolving to gather more information. For example, the pixel count of CMOS image sensors used in cameras is increasing, which leads to more data processing and higher power consumption. Another constraint is that the camera modules must be small, efficient and discreet – no one wants to ruin the design of a car with a camera sticking out from the bodywork. So how can you power your next-generation ADAS camera modules to support more data-gathering capability and smaller sizes?
You first have to think about whether to use a DC/DC switching regulator or a low-dropout regulator (LDO) for each of the rails in your system. LDOs are a great choice if your current requirements are low or if the rail is very sensitive to noise (such as the analog input rail of a CMOS image sensor). However, with the trend toward higher pixel counts and increased power consumption, a DC/DC switching regulator will often be a better choice to minimize power losses and temperature rise.
Then, you must decide on your power tree. You have three main options:
We offer solutions for all of these options, as you can see in Figures 1-3.
Figure 1: Example of the highly integrated approach with the Automotive Camera PMIC Power Supply Reference Design with Power Over Coax Filter
Figure 2: Example of the discrete approach with the Automotive 2-MP camera module reference design with MIPI CSI-2 video interface, FPD-Link III and POC
Figure 3: Example of the partial integration approach with added precision diagnostics for the supply voltage rails
Using a dual step-down DC/DC converter for partial integration provides a simpler bill of materials than a discrete DC/DC switching regulator and offers more flexibility on the layout than a full-fledged PMIC, which is a good compromise between making your design simpler and keeping the layout flexible to best address the size constraints of camera modules.
TI is releasing two new fixed-output-voltage versions of a dual-channel step-down converter that are good choices for your automotive camera module designs. The TPS62423-Q1 and TPS62424-Q1 have a small 3mm-by-3mm package and no need for external resistor dividers.
The fixed output voltages of these new devices were chosen specifically to meet the power requirements of the latest CMOS image sensors, as you can see in Table 1.
OV2311, OX03A10, OV7916, AR0231AT
OV10640, OX02A10, OV10642, OV10650, OV7261
Table 1: Matrix of image sensors and the matching power supply
It’s an exciting time to be an engineer working on automotive electronics and ADAS, and TI is working hard to support you with the products you need to get your next camera module power-supply design rolling, no matter which power architecture you decide on.
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