Cold starts, voltage drops, and multiple power rails can break automotive displays. This design shows a simple, reliable way to keep them running safely.
Automotive display modules face several critical power challenges. Systems must operate reliably during cold cranks, survive sudden voltage drops or spikes caused by load dump events, and continue functioning under low battery conditions. At the same time, designers need to meet functional safety requirements, such as compliance with automotive safety integrity levels (ASIL). Multiple voltage rails are typically required for subsystems like local dimming backlights, display timing controllers, and high-speed communication interfaces. Each rail must be precisely monitored for faults, and the system must recover safely from abnormal conditions. Achieving all of this in a compact, energy-efficient design while minimizing electromagnetic interference presents a complex engineering problem.
PMP41085, the reference design from Texas Instruments (TI) addresses these challenges through a multi-stage approach. The first stage focuses on input protection. It safeguards the system against negative voltage, undervoltage, locked output conditions, and overcurrent events. This ensures that the downstream circuitry is isolated from potentially damaging input conditions and can operate safely even in extreme automotive scenarios.
The second stage is designed to maintain stable operation during low battery conditions, such as at startup. It functions as a pre-boost stage, raising the input voltage when the battery is weak. This allows the system to deliver full power even from a partially discharged battery. The stage supports voltages as low as the minimum battery level, while providing sufficient power to drive the display module and its subsystems. By handling these conditions, engineers can rely on the system to start correctly and operate consistently, even in challenging electrical environments.
The third stage handles the regulated supply of multiple voltages required by display subsystems. It provides dedicated power for the local dimming backlight, timing controller, and high-speed interfaces such as SerDes. Each voltage rail is designed for high efficiency, low electromagnetic interference, and high power density, ensuring that the display module performs reliably without excessive heat generation or footprint. This stage also allows the system to meet strict performance requirements while operating within automotive space constraints.
Voltage monitoring is integrated throughout the design to detect overvoltage, undervoltage, and other fault conditions on each rail. Programmable delays and reset features allow the system to recover gracefully from transient faults, ensuring both operational reliability and safety compliance. This monitoring is essential for supporting functional safety requirements such as ISO 26262, as it provides real-time feedback to the system and enables corrective actions when needed.
The reference design delivers a complete 100 W power solution that operates even at low battery voltages. It combines robust input protection, pre-boost capability for weak batteries, multiple regulated outputs for display subsystems, and comprehensive voltage monitoring. For engineers, this design addresses the key challenges of automotive display power supply design, including cold crank survival, load dump tolerance, multi-rail regulation, safety compliance, and system reliability. By implementing this approach, automotive designers can reduce development time, improve system robustness, and ensure that display modules operate safely and consistently under real-world conditions.
TI has tested this reference design. It comes with a bill of materials (BOM), schematics, assembly drawing, printed circuit board (PCB) layout, and more. The company’s website has additional data about the reference design. To read more about this reference design, click here.
