How LED Backlight Drivers Enable Bigger, Higher Resolution Automotive Displays
February 21, 2019
| By: Szu-Kang Hsien
Executive Business Manager, Automotive Business Unit
Step inside a new car today and you’ll be greeted with sharp screens that help you navigate, provide entertainment, and keep you up-to-date on your vehicle’s performance. Like the TV screens inside our homes and offices, automotive displays are getting bigger and delivering higher resolution, thanks to the infotainment and instrument cluster systems driving this trend.
Providing this level of display performance requires compact electronic components that support low-temperature polysilicon process (LTPS) panels, address electromagnetic interference (EMI) concerns, and provide the dimming capability needed for better readability. Light-emitting diode (LED) backlight driver technology can help simplify the design process for these displays.
By 2023, we could start to see screen sizes greater than 34 inches inside our cars, according to analyst projections. 4K and, eventually, 8K will become standard. And, particularly as the industry makes advancements toward Level 5 fully autonomous vehicles, there could be up to 10 displays inside future vehicles. Many cars already have up to eight displays, when you consider the instrument cluster, the center information display (CID), the smart back mirror, heads-up display (HUD), rear seat mount on the head support, and rear seat mount on the roof.
Automotive displays, in particular the center stack and the instrument cluster, are commonly based on thin-film transistor (TFT) liquid crystal display (LCD) technology. These types of displays consist of tiny switching transistors and capacitors that are arranged in a matrix pattern on the display glass. There are various factors that can impact display performance. Let’s take a look at a few that can be addressed with LED driver technology:
- Screen size and current levels: As displays grow in size, so too does the LCD bias, which means that they’ll need more current to drive the higher voltages. The timing controller (TCON) won’t be up to the task at these current levels, so designers will need to integrate an LED driver. Small form factor at the right current levels will be essential for this component.
- Support for LTPS panels: LTPS panels support higher resolutions and faster responding displays, but these types of displays require a positive analog supply voltage, a negative analog supply voltage, and regulated output voltages to bias the TFT.
- Dimming: Proper dimming makes all the difference for good screen visibility in different driving conditions. An LED driver with a high dimming ratio can help.
- EMI: Mitigating both internal and external sources of EMI is important in ensuring reliable performance of displays in safety-critical applications like ADAS. Seek LED drivers with features such as phase-shifting, spread-spectrum frequency modulation, and hybrid dimming to minimize EMI.
- Display sequencing: When panels from different vendors are incorporated into the same vehicle design, their timing will need to be closely coordinated, as each panel will probably have different power rails to turn on first. A flexible sequencing capability will be useful here.
New Automotive TFT Bias with LED Driver
Maxim’s recently introduced MAX20069 is ideal for displays 8 to 12 inches and beyond. The automotive-grade device, which brings together a 4-channel, 150mA LED backlight driver and a 4-output TFT-LCD bias, addresses many of the display design challenges discussed in this post. For a deeper dive into display design and to learn how the MAX20069 can help, read my white paper, “Simplifying the Design of Bigger, Higher Resolution Automotive Displays.”
Automotive displays are getting bigger and sharper, which creates more design challenges to address in order to yield high-performing results. LED driver technology can help.