Under the trend of automotive area controller architecture, the typical circuit designs of these three categories are changing.

The automotive market is turning to the trend of regional controller architecture, and the automotive regional controller architecture is developing in a distributed, integrated, and intelligent direction to achieve more efficient data processing, functional integration, and autonomous driving support. The regional controller-based architecture brings many design opportunities and challenges. For example, SmartFETs are increasingly replacing traditional MOSFET devices.

SmartFET is a power MOSFET device that integrates intelligent control and protection functions and has been widely used in electric vehicles today. On the basis of traditional power switching components, SmartFET adds functions such as overcurrent, overheating, overvoltage protection, and real-time monitoring and diagnosis. By integrating current sensing, temperature compensation, and adaptive switching control technology, SmartFETs can automatically adjust their behavior based on actual operating conditions, preventing potential failures, simplifying circuit design, and reducing the need for external components.

For example, in the field of automotive electronics, ON Semiconductor provides high-side SmartFETs that not only efficiently switch loads such as LED lighting, starters, door modules, HVAC and other actuators, but also feature active inrush current management, Features such as over-temperature shutdown, automatic restart, and active over-voltage clamping greatly improve the stability and service life of the entire system.

Usually when using MOSFET, you must first have a suitable driver, such as a suitable gate resistor. At the same time, in order to prevent damage to the field effect transistor, we must have various protection measures, such as overcurrent and mild overvoltage protection circuits, to ensure that it operates reliably for a long time without being damaged. Usually these protection circuits are implemented by discrete components, which not only increases the system cost, but also occupies a large PCB space.

SmartFET products integrate these driving and monitoring protection circuits into the standard MOSFET package. Therefore, a SmartFET consists of two main components: first, it has a power stage based on standard MOSFET that is responsible for providing current to the load; the second is the control level, which mainly refers to the driving and monitoring protection circuit of the MOSFET. With this control level, the MOSFET can be switched on and off correctly and at the same time, its damage can be prevented. This can not only increase the reliability of MOSFET use, but also save system costs and reduce the space occupied by the PCB. These advantages make SmartFET widely used in automotive electronics.

High-side and low-side drivers are two basic methods for controlling the switching of loads in circuits. They are widely used in fields such as power management, motor control, and automotive electronics. Specifically:

Low Side Driver (LSD) : In a circuit powered by a DC power supply, low side drive refers to turning on and off the load current by controlling the switching element connected to the load ground (or ground terminal). Break. When this "switch" (usually a MOSFET or transistor) is on, the load can form a loop and draw current from the supply; when the switch is off, the path between the load and ground is severed, stopping the flow of current.

High Side Driver (HSD) : High side driver refers to controlling the load current by controlling the switching element connected to the positive side of the load power supply. High-side drive is relatively complicated because it needs to deal with issues including ensuring that the gate drive voltage is higher than the power supply voltage to ensure that the MOSFET is effectively turned on, and a charge pump or bootstrap circuit must be considered to provide sufficient gate drive voltage. When the high-side switch is turned on, a path is formed between the load and the power supply to start working; when the switch is turned off, the load loses the upper power supply and current no longer flows through the load.

To sum up, between a power supply and a load, if the load is controlled by controlling the switch on the lower side (near the ground), it is low-side drive; if the load is controlled by controlling the switch on the upper side (near the positive pole of the power supply), it is High side driver. Both methods have their own advantages, disadvantages and applicable scenarios. When designing, choose the appropriate method based on system requirements, efficiency, security and other factors.

Due to the integration of various detection and protection circuits, high-side SmartFETs are actually able to handle a wide variety of loads. Common applications can be divided into three categories.

The first category is light bulbs and capacitive loads . The characteristic of this type of load is that there will be a surge voltage when they first turn on. For example, when a light bulb is cold, its resistance is relatively small. The current when it first turns on will be much greater than its rated current. This is especially true for capacitors, which have a charging current when they first turn on. At this time, the high-side SmartFET is required to be able to handle this surge current. These typical loads include lighting inside and outside the car, or various DCDC power modules commonly found in ECUs, etc.

The second type of load is the inductive load . Loads such as various motors and relays have a common characteristic. When the coil with energy inside is disconnected, there must be a freewheeling circuit. At the same time, an induced voltage (also called reverse current) may be generated in the primary coil. excitation voltage). These flyback voltages will generate overvoltage on the power device, and this overvoltage must be clamped to a reasonable range to ensure that it will not cause damage to the MOSFET power switch. Such loads include motors and relays for wipers, starters, door modules, HVAC, fuel injectors, electric power steering, throttle controls, etc.

The third category is resistive load . The resistive load itself has neither surge current nor overvoltage, but in order to know the changes in the load in time, accurate current detection capability is required. For example, in LED applications, if one LED in a string of LED lamp beads is damaged, the current of the LED string will change. This change may not be significant, but it needs to be detected promptly and accurately. In addition to LED lighting, such applications include heating units, transmissions and engine management systems.

An important trend in the current automotive market is that automotive electronic and electrical architecture has begun to shift to a regional controller architecture. The zone controller architecture is used to replace the already widely used domain controller architecture. The so-called regional controller architecture means that the electronic control units are organized and divided according to the physical location of specific areas rather than according to functions. For example, the left body, the right body, the front body, etc., the corresponding required functions are organized according to the physical location to form a regional controller. These area controllers are connected via high-speed Ethernet. These Ethernet networks not only transmit and process data, but also transmit and distribute power, thereby greatly reducing the complexity and weight of the wiring harness (it is worth mentioning that the wiring harness is currently the third heaviest and third most expensive component on electric vehicles).

It can be simply attributed to the fact that the regional controller architecture is replacing the wiring harness with the network, that is, the wiring harness in the domain controller has now become the network. This network is not only a data network, but also a power network. Because the regional controller architecture is a ring network composed of Ethernet, it is easy to expand, and the corresponding regional control can be added or subtracted according to the configuration of low, medium, and high levels. In this way, it is easy to achieve rapid product market launch.

Based on the regional controller architecture, not only data is transmitted and processed through the network, but power is also distributed through the network on a hierarchical basis. Therefore, SmartFET will be of great use: used as the efuse of the entire zone controller to protect the circuit from damage due to surge current or high voltage; at the same time, it can also control the power on and off of the entire zone controller architecture; You can also use SmartFET to decide when to connect the load to the power supply and when to disconnect the load from the power supply.

SmartFET is an advanced semiconductor switching solution designed to provide efficient, reliable power management for automotive and industrial applications. Its structure combines vertical power MOSFETs and intelligent control logic to achieve compact packaging and optimized performance. The design concept focuses on providing highly integrated protection features such as over-temperature protection, overload protection and short-circuit protection to ensure safe operation of the system under various fault conditions. SmartFETs also feature analog current sense outputs to support accurate load monitoring.

As a major supplier of SmartFET product technology, ON Semiconductor has considered compatibility with controllers in product design, making it easier to switch between SmartFETs of different sizes and different RDS(ON), providing greater flexibility for applications. flexibility. The entire ON Semiconductor series, from 1 milliohm to 60 milliohms, from 1 amp to 20 amps, has the same package, the same silk screen, the same instruction structure and the same high reliability. Therefore, when designing and making the regional controller architecture PCB board, it has considerable versatility and flexibility, and the PCB board will not have to be remade due to external load changes, which is a very big advantage.