Power chip selection and design challenges

Smart car cockpits are usually equipped with a variety of features that enhance the driving experience. For example, the full LCD central control screen and high-definition display can make the user experience smoother and simpler; the driver can make calls and achieve intelligent navigation through voice recognition; high-quality audio and ambient lighting can provide an immersive experience of watching movies and listening to music. In addition, wireless download (OTA) technology can seamlessly connect the driver's mobile phone to the vehicle system; the smart cockpit can even monitor the driver's status and provide emergency road condition warnings, making driving safer.

The car's smart cockpit is not only a powerful travel assistant, but also a bridge connecting users and digital intelligence. The frequent and close contact between consumers and vehicles is reflected in the cockpit; through the cockpit system, consumers can specifically see that the car is becoming more and more intelligent and innovative.

According to iCVTank, the global smart cockpit market was worth $23.1 billion in 2020 and is expected to reach $44 billion by 2026. The in-vehicle infotainment market is the largest, accounting for 64.3%, followed by cockpit display systems at 27.05% and head-up display systems at 4.62%. Among the key factors that influence user purchasing decisions (such as power, space, and price), cockpit configurability has become an important consideration.

This article will discuss the hardware support system of the automotive smart cockpit solution by introducing the reference board jointly developed by MPS and SemiDrive Technology. In addition, it will discuss three key power solutions, including primary power supply, secondary power supply and backlight drive solution.

Computing power of the car’s smart cockpit

The 2021 Automotive Smart Cockpit White Paper points out that the computing power of the main SoC is the key to determining the cockpit's functions and performance. The computing power of the central processing unit (CPU) is mainly measured in millions of instructions per second (Dhrystone DMIPS), which refers to the number of millions of machine language instructions processed per second. In order to meet the ever-expanding application coverage, the computing power requirements of the CPU are also increasing. As of now, SoCs with more than 20kDMIPS are sufficient to meet the requirements of smart cockpit processors, and the demand is still increasing.

The smart cockpit of a car can provide a variety of functions, including head-up display system, visual perception system and voice interaction system. Figure 1 gives an overview of the typical functions of the smart cockpit system.

Figure 1: Typical functions of a smart cockpit

We will explore the hardware architecture of the smart cockpit solution through the high-performance CoreDrive X9 chip (see Figure 2).

Figure 2: CoreDrive X9 series cockpit chip (Image source: CoreDrive Technology)

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Power Supply Design for Automotive Infotainment Systems (Part 1)

Understand the characteristics of primary and secondary power supplies

Reference Design

Versal AI Edge (Automotive Grade) Full Power Management Reference Design

From cold start to load dump

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The X9 series processors are automotive-grade chips from CoreDrive Technology for the next generation of automotive electronic cockpits. This series of new smart cockpit technologies integrates high-performance CPUs, graphics processing units (GPUs), AI accelerators, video codec processors, and other acceleration units. A single X9 processor can drive up to 10 high-definition displays (such as instrument panels, center consoles, rearview mirrors, and rear entertainment systems) at the same time, and supports multi-screen sharing and interaction to meet the functional requirements of future automotive smart cockpits (see Figure 3). The X9 processor also integrates a wealth of interfaces and bus protocols, such as PCIe, USB, CAN-FD (Flexible Data Rate Controller Area Network), and Ethernet. Therefore, this series of processors can seamlessly connect various types of vehicle systems at a low cost.

The X9 series includes X9E, X9M, X9H, X9HP and X9U. These processors are equipped with different numbers of CPUs and CPU cores, with a maximum computing power of 100k DMIPS, covering a variety of cockpit application scenarios such as LCD instrumentation, central control navigation, and high-end smart cockpits. In addition, the entire X9 series is compatible with a variety of software and hardware, which can help customers reduce development costs and shorten development cycles, and a single design can be applied to applications of different models.

MPS and SemiDrive jointly develop X9H reference board

X9H is a high-performance cockpit chip in the X9 series, using 6-core A55 plus several R5 cores, with a CPU computing power of up to 36K DMIPS and a GPU computing power of up to 140 GFLOPS. The X9H reference board jointly developed by MPS and CoreDrive can realize a smart cockpit solution with up to 4 screens linked. The input of the reference board is directly powered by a 12V battery. Since the power supply rail of the SoC is usually at a voltage level below 1V, it is recommended to use a two-stage power supply solution to improve the system conversion efficiency and cope with battery voltage fluctuations during cold start and load dumping.

Primary power supply solution

The first stage uses the MP4436-AEC1 to convert the 12V power supply to 5V. The MP4436-AEC1 is an adjustable frequency automotive grade synchronous step-down switching regulator with a maximum input voltage (VIN) of 45V and a maximum output current (IOUT) of 6A. It also supports parallel configuration (see Figure 4).

Figure 4: MPS primary power solution: MP4436-AEC1

The functional features of MP4436-AEC1 are described as follows:

4mm x 4mm ultra-small package size reduces board layout area;

Ultra-high conversion efficiency supports heat dissipation in complex cabin environments;

The dynamic performance provides stable output for the subsequent circuit;

The scalability of supporting multiple parallel connections increases customer design flexibility and platform inheritance;

Extensive internal protection features ensure system reliability, such as over-current protection (OCP) with hiccup mode and input under-voltage protection (UVP).

There is also a spread spectrum function (FSS) version of MPQ4436A-AEC1. The spread spectrum function can reduce the EMI interference of the system and reduce the difficulty of EMI design of the customer's entire board. Customers can flexibly choose according to their needs.

Secondary power supply solution

The MPQ217x automotive-grade switching regulator family offers flexible pin-to-pin compatibility with the X9E, X9M and X9H. The family of regulators includes the MP21777-AEC1(1A I)OUT), MP2178-AEC1(2A I)OUT) and MPQ2179-AEC1(3A I)OUT), all of which support a unified hardware layout across different platforms.

Taking X9H as an example, its secondary circuit is composed of multiple MPQ2179-AEC1 and MP2167A-AEC1(6A I)OUT) according to the current requirements of different SoC power rails.

Figure 5 shows the system architecture of the secondary power solution.

Figure 5: Secondary power solution system architecture

The secondary circuit implemented with MPQ2179-AEC1 and MP2167A-AEC1 has the following advantages:

The MPQ2179 and MPQ2167A are specifically designed for 5V applications such as infotainment, ADAS, cameras and smart cockpits, which require fast transient response, ultra-low noise, high-precision output and good thermal performance.

MPS' latest Bipolar-CMOS-DMOS (BCD) low-resistance process, combined with advanced flip-chip packaging technology, can achieve higher system efficiency.

The MPQ2179-AEC1's high 2.4MHz switching frequency (fSW) reduces inductor size, avoids the AM radio band, and reduces interference with automotive radio bands.

The MP2167A-AEC1 is available in a small (3mmx3mm) package, and its operating frequency can be set by external resistors up to 2.2MHz. The device also integrates a rich set of protection functions, including cycle-by-cycle over-current protection (OCP), output short-circuit protection (SCP), input under-voltage protection (UVP), and output over-voltage protection (OVP).

Backlight drive solution

X9H can support up to four full HD displays, and backlight driver chips are required for screen lighting and dimming. Taking MP3364-AEC1 as an example, this device is a boost WLED driver with a maximum operating frequency of 2.2MHz, a maximum drive current of 150mA per channel, and a maximum output voltage (VOUT) of up to 50V (see Figure 6).

Figure 6: MP3364-AEC1 Typical Application Functional Block Diagram

The functional features of MP3364-AEC1 are described as follows:

Supports I2C interface, and the chip itself supports 3 I2C addresses. The same I2C bus can support 3 chips, which is convenient for configuring multiple chips;

Three available dimming modes are provided: pulse width modulation (PWM) dimming, analog dimming and hybrid dimming (PWM and analog dimming), which can be selected through external pins. The PWM dimming ratio and analog dimming ratio are up to 15000:1 and 200:1 respectively, and the fine dimming ratio can achieve fine adjustment of screen brightness.

Supports cycle-by-cycle current protection, LED open circuit protection and short circuit protection (SCP), inductor short circuit protection (SCP0), output overvoltage protection (OVP) and over temperature protection (OTP). Rich internal protection functions ensure safe and reliable operation of the backlight drive system.