The Tesla Model 3 is changing our impression of the vehicle dashboard. Gone are the multiple gauges, buttons, and knobs that we’re accustomed to. Instead, when you step into the driver’s seat, the car’s 15-inch touchscreen takes center stage, providing access to all driver controls. When it comes to automotive displays, vehicle manufacturers are starting to incorporate more screens—and bigger, sharper ones—inside their cabins. Displays for functions such as advanced instrument clusters, heads-up displays, infotainment, center displays, rear-seat entertainment, and smart mirrors are delivering vivid images of the surrounding environment, automotive controls, and infotainment options.
What’s more, as vehicles are equipped with more autonomous functions, displays will continue to play a critical role for safety as well as convenience. Premium vehicles may boast as many as 10 displays. Over the next several years, we may see vehicles with screens larger than 34 inches becoming common and resolutions of 4K (and, eventually, 8K). Adding more screens to each car, however, involves a complex balancing act since the power supply circuitry for these screens competes with many other electronic systems for the limited space inside the car. A smaller and simplified PCB is desired, as this would reduce the bill of materials (BOM) and, consequently, related costs.
An effective automotive display must address:
- Power requirements
- Functional safety standards
- Electromagnetic interference (EMI)
- Contrast ratio guidelines
To meet these demands, the power solutions for these displays will need to be precise, flexible, and small. In this blog post, I’ll highlight the automotive power management capabilities that are needed to fulfill the requirements for large, high-resolution displays. Also, I’ll be speaking on the topic at a couple of upcoming events. You can learn more by attending:
- “Matrix Local Dimming LED Driver for Local Dimming Automotive Displays” from 9:00a.m. to 9:20a.m., Thursday, February 27, at the electronic display Conference (during embedded world 2020)
- “Highly Integrated TFT Bias with Functional Safety for Automotive Display Application,” on Tuesday, March 17, at APEC 2020
A typical TFT-LCD display gets its power via multiple ICs. A high-voltage buck converter provides the main 3.3V rail, which feeds the remaining low-voltage circuits. A low-voltage LDO provides rails which are critical to noise. A low-voltage buck converter provides the deserializer rail. A high-voltage, low-standby-current LDO provides always-on power to the microcontroller unit (MCU). And a watchdog timer resets the local MCU if the input isn’t pulsed periodically. As you can see, the power management system for this TFT-LCD display example is quite bulky and complex. Is there a way to streamline all of this, without sacrificing display quality while also making functional safety easier to achieve?
A highly integrated power management approach accomplishes what’s outlined in our example using just two ICs. A single power management IC (PMIC) accommodates a five-block stack that includes the high-voltage buck, a high-voltage LDO, the watchdog, a low-voltage LDO, and a low-voltage buck. With this integration comes better control and sequencing of the different voltage rails.
The PMIC in this scenario is the MAX16923 automotive 4-output display power solution with watchdog, the market’s smallest, most integrated automotive PMIC for high-performing, < 12.3” vehicle display modules. While the closest competitive solution requires at least five discrete chips, the MAX16923 integrates into a 480mm2 space:
- A high-voltage 2.1A buck converter
- A high-voltage 100mA LDO
- A low-voltage 1.6A buck converter
- A low-voltage 180mA LDO
- And a watchdog
Spread spectrum (±3%), slew-rate controlled switching, and adjustable switching frequency mitigate EMI, while differential output voltage variation provides design flexibility. A second highly integrated IC, the MAX20069, provides the LED backlight and TFT driver functions. Together, these two ICs meet all of the power supply requirements for an automotive display.
These devices are part of Maxim’s expanding portfolio of power ICs for automotive displays. In this portfolio, you’ll find highly integrated, automotive-grade ICs that meet ASIL requirements, come with features that mitigate EMI, and are capable of enabling crisp, vivid displays.
For greater insight on designing high-quality automotive displays, read:
- "PMIC Streamlines Automotive TFT-LCD Display Design"
- "How LED Backlight Drivers Enable Bigger, Higher Resolution Automotive Displays"
- "Digital Instrument Clusters: Why Functional Safety is Important"