Reference Design Of An Automotive 400-V to 12-V Unidirectional Converter

Reference design for an automotive 400-V battery to 12 V, 3.6-kW DC/DC converter.

Most new Electric Vehicles (EVs) have high voltage battery packs, but auxiliary systems such as lightning systems, infotainment systems, safety systems, etc. in cars and other vehicles still run on 12V DC. Although the power consumption of these individual systems is not that high, the cumulative power of all the systems when running together can add up to 1000s of watts. Therefore, it is important to have a safe and reliable DC / DC converter that can work in harsh working conditions and provide constant 12V DC output.

To solve this problem, Texas Instruments designed a 3.6 kW DC/DC converter that can handle a wide input range from 200V to 470V and provide a 12 V output. The output is adjustable from 9V to 15V with a maximum current of 300Amps. The output is scalable to 800-V input systems, with tight regulation of <±1%. The converter also provides soft-switching using a phase-shifted full bridge analog control loop. A circuit breaker is used for overcurrent and overvoltage protection. The reference design uses Sic MOSFETs on the high-voltage side and is driven by 5.7-kVRMS, stabilized isolated dual-channel gate drivers.

The reference design also features Zero Voltage Switching (ZVS) over a wide range of operating conditions. It also features various light load management features such as dynamic SR on and off control and burst mode, etc. A fast circuit breaker is implemented to comply with automotive safety.

This reference design was tested by Texas Instruments. To simplify the design, TI provides the firmware libraries, BOM, Gerber files, etc., which can be found in the Design guide PDF of TIDA-020031. You can find more data about the reference design on the company’s website. To read more about this reference design click here.