DC/DC converters in automotive applications

It has been said that the modern car is a mobile data center, and EVs add-in industrial scale electrical power handling, battery charging and motor drives that are now rated in fractions of a megawatt. In a modern car there are upwards of 100 Microprocessors and controllers operating in the background, handling everything from wireless connectivity, to heated seats, to implementation of complex algorithms for three-phase control of the traction motors to squeeze out the best efficiency and range.

All this electronics needs its own power rails and these derive from the battery, whether a 12V/24V lead-acid type or a lithium-ion pack at up to 800V. As in data centers, power bus architectures have been devised in cars to minimize losses and particularly weight, and DC/DC converters are an integral component to provide the voltage conversion stages from battery to end load. Among these DC/DCs, non-isolated Point-of Load (PoL) converters are fitted close to each sub-system and processor to give the best regulation and dynamic performance exactly where it is needed. Other DC/DCs such as LED drivers are also common.

A web search will show PoLs and LED drivers as being one of the most ubiquitous types of DC/DC converter with a wide variety of features and ratings. However, in the automotive application, the choice has to narrow to types with the right qualification, defined by the Automotive Electronics Council, (AEC) founded by Chrysler, Ford Motors and Delco Electronics, who set standards for stress testing, qualification and production quality control of components in the automotive arena. The Standards are designated AEC-Qxx and currently relate to stress testing of ICs (AEC-Q100), discrete semiconductors, (AEC-Q101), optoelectronics, (AEC-Q102), sensors (AEC-Q103) and ‘multi-chip modules’ (AEC-Q104).

Passive components are covered by a range of standards in the AEC-Q200-xxx series and in all cases, standards from other sources such as MIL-STD-883, JEDEC, JESD, IPC and UL are referenced. Component manufacturers ‘self-certify’ that they meet the AEC-Q standards but they are a ‘base’ level, and further requirements will be set by the automotive customer at any tier, for their particular application. At a minimum this will define the area of the vehicle where the part is used with its environmental conditions defined. For example, ambient operating temperature is defined for different areas for ICs in Table 1.


As a separate requirement, a component supplier to the automotive industry must have a quality system with TS/IATF 16949:2016 certification, a step-up from the commonly used ISO 9001:2015. There is strong emphasis in the AEC-Q standards on the ability of a supplier to maintain the stress tolerance of components in their real manufacturing process. Although the AEC-Q stress tests need only be done once, parts must be used which have been fabricated using production tooling, processes and operatives, using non-consecutive lots. If anything in the component or manufacturing process changes, requalification is necessary using a Product Part Approval Process (PPAP). This was determined by the Automotive Industry Action Group and the PPAP has its own levels of applicability ranging from 1 to 5 with increasing requirements for supporting data and sample submission as shown in Table 2.


PPAP is part of an over-arching requirement of Advanced Product Quality Planning (APQP) which includes comprehensive documentation of the manufacturing process, test records and design/process failure mode and effect analysis (FMEA).

Examples of products with wettable flanks recently introduced by RECOM are their RPX-0.5Q/RPX-1.5Q PoL DC/DCs and their RPY-1.5Q LED driver, Figure 2.