May 16, 2019
|By: Chintan Parikh
Executive Business Manager, Automotive, Maxim Integrated
When cameras are expected to be the eyes on the road in today’s vehicles, they must perform reliably and efficiently. They are, after all, critical components in advanced driver assistance systems (ADAS). Blind-spot monitoring, parking assistance, driver monitoring, and front-view cameras are just some of the applications and systems that rely on high-resolution automotive cameras. According to Strategy Analytics, automotive cameras are anticipated to experience brisk growth in the coming years, with side-mounted cameras projected to have a CAGR of 16% through 2025.
Typically automotive cameras are installed in various spots on the vehicle’s interior and exterior. ADAS cameras capture image data that must be quickly and efficiently moved to the processing unit and from the processing unit to each of the vehicle’s displays. These cameras are in increasingly small enclosures, however, so designers need to strike a delicate balance between their power demands and power constraints.
Blind-spot monitoring is one of many safety-critical applications supported by vehicle cameras, which rely on power-management systems that must meet stringent criteria.
The cameras’ on-board power management systems must meet some stringent criteria:
Remote camera modules are generally powered by a power-over-coax (POC) ~8V rail, consuming about 1W or less. To power the on-board electronic loads, which includes the imager and the serializer, the rail is bucked down to three voltage rails. Since the camera is either on at full operation or completely off, buck converters designed for high efficiency at full load (without additional silicon to enhance light-load operation) provide a cost-effective option. A typical power management solution involves discrete bucks and/or LDOs—with a single/dual dedicated, 8V-powered device. This overall design, given the discrete bucks and their related passive components, also requires a fairly large footprint.
Dual buck-converter ICs provide a more efficient and compact solution for remote automotive cameras. Two of these devices can cover the four rails, saving space and enabling efficiency. For example, MAX20019 dual step-down converter with integrated high-side and low-side MOSFETs is ideal for surround-view camera power supplies as well as automotive point-of-load applications. In this power-management IC (PMIC), two integrated buck converters operate in a cascaded fashion, working at or near full load and high duty cycle to deliver the highest efficiency possible. Another PMIC option for vehicle camera modules is the new MAX20049, which integrates four power supplies (dual bucks and dual LDOs) in a 38mm2 PCB footprint that delivers the highest efficiency currently available. At full load, system efficiency is 74%. The device also features over-voltage protection, under-voltage lockout, external power good (PGOOD) signal, and cycle-by-cycle current limit. The MAX20049 can be powered directly from the coaxial cable or be cascaded, which provides flexibility to adjust the design layout and fine-tune the IC to meet application-specific requirements.