Understanding automotive chips in one article - power conversion chips-EEWORLD

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1. Introduction to power chips

A power chip is an integrated circuit chip that converts or controls power to provide a suitable voltage or current for the normal operation of the load. It is a very important type of chip in analog integrated circuits. It generally includes power conversion chips, reference chips, power switch chips, battery management chips, and other categories, as well as power products for some specific application scenarios. Power conversion chips are usually divided into two types of chips: DC-DC and LDO (low dropout regulator) according to the chip architecture. Power management chips can also be roughly divided into the following six categories:

AC/DC modulation IC, containing low voltage control circuit and high voltage switching transistor;

Power factor control PFC pre-modulation IC, providing a power input circuit with power factor correction function;

Pulse modulation or pulse amplitude modulation PWM/PFM control IC, which is a pulse frequency modulation and/or pulse width modulation controller used to drive an external switch;

Battery charging and management ICs. Including battery charging, protection and power display ICs, as well as "smart" battery ICs that can communicate battery data;

Hot-swap board control IC (to avoid the impact of plugging or unplugging another interface from the working system);

The switching function of MOSFET or IGBT IC.

For complex processor chips or complex systems with multiple load chips, multiple power rails are often required. The power supplies must meet strict timing requirements. Some systems also require voltage monitoring, watchdog, communication interface and other functions. Integrating these functions into chips with power as the main body will derive product categories such as PMU and SBC.

Power chips are widely used in automotive electronic systems, and different types of power chips are used in automotive electronic components according to application requirements. As cars move toward electrification, networking, and intelligence, more and more power chips are used in single vehicles, and the number of power chips used in new energy vehicles will exceed 100.

Typical power chip application cases: The application of power chips in automotive motor controllers is mainly used to generate various types of secondary power supplies, such as providing working power or reference levels for the main control chip, related sampling circuits, logic circuits, and power device drive circuits.

Figure 1 shows a traditional automotive motor controller power supply solution, which can meet the system's power supply needs but cannot satisfy the product's certain functional safety requirements.

Figure 1: Power architecture without functional safety requirements

※Source: Public information, provided by the compilation unit

Figure 2 is based on the solution in Figure 1, but uses an SBC chip with monitoring and diagnostic functions to optimize the monitoring and diagnostic functions of the weak current power supply. Therefore, the architecture has a certain functional safety level (such as ASIL B).

Figure 2: Power architecture with certain functional safety requirements

※Source: Public information, provided by the compilation unit

Figure 3 is based on the previous two. The monitoring and diagnosis of the low-voltage power supply are more complete, and a high-voltage/low-voltage DC-DC backup power supply is added to meet the requirements of the highest safety level (ASIL D). The dotted box notes the power topology built using the power chip.

Figure 3: Power architecture for functional safety ASIL D

※Source: Public information, provided by the compilation unit

(Note: the power topology shown here is only a general solution investigated within a certain range and does not represent all application cases of the power supply in the motor controller of the vehicle, the same below).

2. Power conversion chips

Flash memory, as a storage medium, is widely used in storage products such as solid-state drives, UFS, eMMC, SD cards, and USB flash drives. Flash memory is a non-volatile memory, which means that data will not be lost even if the power is turned off. The power supply for the vehicle system usually comes from the battery. Passenger cars and commercial vehicles generally use 12V and 24V battery voltages, respectively. Due to the special working conditions of the vehicle system, the voltage has a certain fluctuation range. For specific power-consuming chips in the vehicle system, the battery voltage cannot be used directly, and a power conversion chip is required to convert the battery voltage to the voltage value required by the chip. The following analyzes the two categories of DC-DC switching power supplies and LDO linear power supplies. (1) DC-DC switching regulator

A DC-DC switching regulator refers to a DC voltage to DC voltage regulator, often referred to as a switching power supply. The power tube of a DC-DC chip operates in a high-frequency switching state, using inductors and capacitors for energy storage and filtering to achieve the function of voltage conversion. Depending on whether the power tube is external or internally integrated, the DC-DC chip can be further divided into a DC conversion controller and a DC switching converter. Usually, a DC conversion controller architecture is used for high current output scenarios, and a DC switching converter with integrated power tubes is used for application scenarios with smaller current output. According to the relationship between the output voltage and the input voltage, it can be divided into several common topology architectures: Buck, Boost, and Buck/Boost. In addition, there are also topology architectures such as Sepic, Cuk, and Zeta. Since the latter is relatively less used in vehicle systems, this article will not expand on it. The following table shows the classification, main functions, key parameters, and application scenarios of DC-DC switching regulators.

DC-DC switching regulator situation

※Source: Public information, provided by the compilation unit

(2) LDO Regulator

LDO Regulator refers to a low drop-out linear regulator, which is also widely used in voltage conversion in automotive systems. Unlike DC-DC switching regulators, the power tube of a linear regulator does not operate in a high-frequency switching state, but at a specific point on the output characteristic curve. Compared with DC-DC chips, LDO has the advantages of lower noise, fewer external passive components, simpler circuits, and less EMC interference. However, the power conversion efficiency of LDO is low, especially when the input-output voltage difference is large, the heat generated is significantly higher than DC-DC, so it is not suitable for high-current output scenarios, and the output current is usually within hundreds of mA to several amps.

LDO can be divided into general-purpose LDO and follower LDO according to the output voltage adjustment method. General-purpose LDO is the most widely used, and is used in almost every vehicle system. Follower LDO has specific application scenarios, and the output voltage of the LDO needs to change with the output voltage of another LDO or the reference voltage.

The following table shows the classification, main functions, key parameters and application scenarios of LDO Regulator linear regulators.

LDO Regulator Linear Regulator

※Source: Public information, provided by the compilation unit

3. Development of domestic power conversion chips

Power chips are widely used in automobiles, and the technology development of domestic enterprises is relatively mature. Domestic companies represented by Allwinner Technology, Huada Semiconductor, Shengbang Micro, and Lingxin have relatively mature products in the application fields of LDO, chips, DCDC chips, PMU chips, etc., and are currently gradually carrying out domestic introduction.

(1) LDO chip

Domestic LDO situation