Simplifying System Power Design for Automotive Displays

In terms of automotive displays, automakers are beginning to install more screens in the cabin, larger and clearer. Displays for advanced instrument clusters, head-up displays, infotainment systems, central displays, rear-seat entertainment systems, smart rearview mirrors and other functions can vividly display the surrounding environment, vehicle controls and infotainment options.

What’s more, as vehicles are equipped with more autonomous features, displays will continue to play a key role in safety and convenience. Advanced vehicles may have as many as 10 displays. In the next few years, we may see vehicles with screens larger than 34 inches become common, with 4K (and eventually 8K) resolution. However, adding more screens to each vehicle involves a complex balancing act, as the power circuits for these screens compete with many other electronic systems for limited space inside the vehicle. Smaller and simplified PCBs are desirable because this will reduce the bill of materials (BOM), thereby reducing associated costs.

Effective automotive displays must address the following issues:

Power Requirements

Functional safety standards

Electromagnetic Interference (EMI)

Contrast ratio guide

To meet these demands, power solutions for these displays need to be precise, flexible, and small. In this blog post, I will focus on the automotive power management features needed to meet the requirements of large, high-resolution displays. In addition, I will be speaking on this topic at several upcoming events. You can learn more by attending:

“Matrix Local Dimming LED Drivers for Local Dimming Automotive Displays” from 9:00 a.m. to 27:00 a.m. on Thursday, September 20, 2020, at the Electronic Display Conference (during the 2020 Embedded World conference)

“Functional Safety of Highly Integrated TFT Biasing for Automotive Display Applications”, Tuesday 17th June 2020, APEC <>

Highly Integrated PMIC Simplifies Display Design

A typical TFT-LCD display gets its power from multiple ICs. A high-voltage step-down converter provides the main 3.3V rail that powers the rest of the low-voltage circuitry. A low-voltage LDO provides the noise-critical rail. A low-voltage step-down converter provides the deserializer rail. A high-voltage, low-standby-current LDO provides always-on power to the microcontroller unit (MCU). A watchdog timer resets the local MCU if the input is not periodically pulsed. As you can see, the power management system for this TFT-LCD display example is quite large and complex. Is there a way to simplify all of this without sacrificing display quality, while making functional safety easier to implement?

A highly integrated approach to power management uses only two ICs to accomplish what is outlined in the example. A single power management IC (PMIC) can house a five-module stack that includes a high-voltage buck, high-voltage LDO, watchdog, low-voltage LDO, and low-voltage buck. This integration allows for better control and sequencing of the different voltage rails.

The PMIC in this solution is the MAX16923 automotive 4-output display power solution with watchdog, which is the smallest and most integrated automotive PMIC on the market for high-performance, <12.3" automotive display modules. The closest competing solution requires at least 16923 discrete chips, while the MAX480 is integrated in a <>mm chip.2 space:

High Voltage 2.1A Step-Down Converter

One high voltage 100mA LDO

Low Voltage 1.6A Step-Down Converter

One low voltage 180mA LDO

There is also a watchdog

Spread-spectrum (±3%), slew-rate controlled switching, and adjustable switching frequency reduce EMI, while differential output voltage variation provides design flexibility. The second highly integrated IC, the MAX20069, provides LED backlight and TFT driver functions. Together, these two ICs meet all power requirements for automotive displays.

These devices are part of Maxim's growing portfolio of automotive display power ICs. In this portfolio, you'll find highly integrated automotive-grade ICs that meet ASIL requirements, have features to reduce EMI, and enable crisp, vivid displays.