While the transition of electric and hybrid electric vehicles (EVs) from standard metal-oxide-semiconductor field-effect transistors (MOSFETs) as power control devices to FETs based on silicon carbide (SiC) substrates and process technology represents an increase in EV efficiency and An important step in overall system-level characterization. However, SiC devices require a new understanding of their key specifications and drive requirements to fully exploit their benefits.
This article provides an overview of EV and HEV power requirements, explains why SiC-based power devices are well suited for this function, and sheds light on the capabilities of their auxiliary device drivers. After a brief discussion of the impact of the AEC-Q101 standard on automotive-grade discrete devices, it introduces two AEC-qualified SiC power devices from ROHM Semiconductor and highlights key features that must be considered for a successful design.

Powering Electric and Hybrid Vehicles Demand for all vehicles - Internal Combustion Engines (ICs), Power Subsystems for Electric and Hybrid Vehicles has been growing exponentially to support Advanced Driver Assistance Systems (ADAS), Power Windows , functions and connections such as doors and mirrors, internal network, radar, entertainment system, GPS, etc.
The primary power source for an IC vehicle is typically standard12] The battery-based power subsystem in an EV provides power for the traction motors and related functions, as well as many of the now-standard features and functions expected by drivers.

In addition to the many small DCs used for internal functions and charging] While many factors determine the overall effectiveness of the power subsystem, the most important is the performance of the switching regulator. They convert the raw battery charge into the voltage/current required by the drivetrain and battery charging.
The reason is simple: at current levels of hundreds of amps, the base current] These static losses point to two well-known strategies to reduce IR drop and I2R losses: 1) reduce on-resistance, 2) increase system operating voltage, Thereby reducing the current required to supply a given amount of current to power the load. For dynamic switching losses, any device improvement that can reduce these losses (related to device physics, switching frequency, and other factors) will have a huge impact.

In the past few decades, the dominant power switching devices were silicon (Si)-based MOSFETs and insulated gate bipolar transistors (IGBTs). While technological advances have greatly improved their performance, improvements have largely stabilized. At the same time, electric vehicles require the feasibility and attractiveness of switchgear with better specifications.
Fortunately, in the past few decades, another solid-state MOSFET process technology has matured, one based on a silicon carbide (SiC) material rather than just basic silicon, consisting of the same parts of silicon and carbon through covalent bonds. connected. Although there are over 100 different SiC polytypes (unique structures) of SiC, the 4H and 6H types are of the most interest due to production and processing reasons.
Standard silicon, 4H SiC and 6H SiC have significantly different critical physical grade electrical performance specifications. The higher bandgap energy and critical electric field value of SiC supports higher voltage operation, while the smaller electron and hole mobility factors result in lower switching losses, enabling operation at higher frequencies (which also results in smaller filters and passive components). At the same time, higher thermal conductivity and operating temperature simplify cooling requirements.
Electrical Properties Si Silicon Carbide (4H) Silicon Carbide (6H) Diamond Bandgap Energy (eV) 1.12 3.28 2.96 5.5
Critical electric field (MV/cm) 0.29 2.5 3.2 20
Electron mobility (cm²/VS) 1200 800 370 2200
Hole mobility (cm²/VS) 490 115 90 1800
Conductivity (W/cmK) 1.5 3.8 3.8 20
Maximum Junction Temperature (°C) 150 600 600 1927
Key electrical properties at the base material level of silicon, two types of SiC, and diamond in comparison
SiC Maturity and AEC-Q101 However, the transition of SiC devices from theoretical promise to practical realization has not been achieved quickly or easily. But over the past decade, SiC-based MOSFETs have come of age, over several generations—each generation bringing process improvements and major structural changes.
For example, ROHM Semiconductor has long offered its second-generation SiC devices, which are widely used in automotive applications. Transition of most standard SiC] from 2 ROHM SiC devices to 2nd to 3rd generation includes process enhancements, as well as major structural changes

3rd Generation SiC with ROHM] Another issue that accompanies mature and multi-generation SiC devices is their ability to be fully AEC-Q101 compliant. The standard is based on a set of specifications from the Automotive Electronics Council (AEC), a group of major automakers and U.S. electronic component manufacturers responsible for establishing reliability tests for automotive electronics. The key agreements are:
AEC-Q100 (IC device)
AEC-Q101 (discrete components such as MOSFETs)
AEC-Q102 (Discrete Optoelectronics)
AEC-Q104 (Multi-Chip Module)
AEC-Q200 (passive components)
The AEC-Q101 standard is much more stringent than the standard widely used in industrial applications. The AEC specification establishes a set of grades, as shown in Table 2. SiC devices can meet grade 0 (-40°C to +] AEC reliability qualification standards that are more challenging than those used for commercial and industrial applications. Note that some Suppliers report that industrial applications are increasingly using the AEC-Q100 series of specifications to ensure enhanced reliability. This is practical from a cost perspective, as the widespread adoption of electronics and components in automotive The price difference of the car.
SiC devices support medium to high current designs
SiC devices are not only suitable for high current applications in EVs. In addition to the powertrain, there are many low-power functions (i.e. power seat/window heaters, seat and cabin heaters, battery warmers, AC motors, power steering) that can be derived from the characteristics of SiC MOSFETs benefit.
For example, ROHM's SCT3160KL is an N-channel SiC power MOSFET, and ROHM's SCT3160KL is a basic N-channel SiC power MOSFET for loads up to 17 A.

The SCT3160KL takes 16] The basic specifications of the SCT3160KL show its suitable power supply requirements for many smaller loads in EVs or other applications The maximum safe operating area (SOA) diagram illustrates how this SiC device is well suited for pulsed duty cycles, which are typically found in Switching power supplies and regulators at higher voltages.
The SOA diagram of the SCT3160KL establishes and limits the maximum limits of drain current, drain-source voltage and pulsed power handling.
Of course, the benefits of SiC-based devices are most evident at higher current levels. Consider ROHM's SCT3022AL, also an N-channel SiC power MOSFET in a TO-247N package. , it is ideal for motor drive power conversion, battery management, and battery charging in EVs] ROHM's SCT3022AL N-channel SiC power MOSFETs are ideal for higher current designs due to their low on-resistance value and other properties
SCT3022AL] Individual power devices - whether silicon MOSFETs, SiC FETs or IGBTs - are only one part of the power conversion/control design equation. In fact, three functions are required for high power "signal chain" operation: controller, gate driver and power semiconductor.

Although SiC devices have similar characteristics to Si devices (and IGBTs) in terms of driving, they also exhibit significant differences. For example, since SiC]SiC drivers require the following:
Relatively high supply voltage (25 to 30 volts), high efficiency higher drive current (typically > 5 A) through low conduction losses, and low impedance, fast slew driver with instantaneous rate of voltage change over time (dV /dt), which enables lower switching losses when drive current flows in and out of gate capacitance Fast short-circuit protection (typically <400 ns response) because SiC devices switch faster than Si devices Reduce propagation delay values and unit-to-unit skew of (again for efficiency)
Finally, ultra-high dV/dt immunity ensures stable operation in high current, high voltage operating environments
SiC-based FETS, Si] Table 5: While Si-based MOSFETs and IGBTs have some similar drive requirements, SiC device drivers have very different specifications. Due to the high voltages these devices operate with various other system topology factors, Regulatory issues related to creep and gap size are often included in design criteria. Additionally, galvanic (ohmic) isolation between the controller and the power device is almost always required.

This isolation can be provided by a separate stand-alone component between the controller and driver, or embedded in a multi-chip driver. The latter option results in a smaller overall footprint, but some designers prefer to use separate isolators so they can choose the isolation technology (e.g. magnetic, optical, capacitive) as well as performance specifications.
For example, the UCC27531-Q1 from Texas Instruments (ti) is an AEC-Q100 qualified (Grade 1) non-isolated single-channel, high-speed gate driver for SiC (and other) devices. It provides up to 2.5 in source mode] Texas Instruments (TI)'s non-isolated UCC27531-Q1 gate driver is well suited to the technical requirements of SiC switching devices, although this small six-pin SOT-23 driver appears to be a simple function Simple components, but effective driving requires detailed attention to the specific needs of SiC devices.
Texas Instruments' isolated SiC driver solutions include Power Integrations' SIC1182K , a single-channel, 8 A SiC gate driver with advanced active clamping and reinforced isolation up to 1200 V. Note that while this isolated SiC driver module is not AEC certified, Power Integrations can offer a very similar family of SID11x2KQ MOSFET/IGBT gate drivers that are AEC-100 Grade 1 compliant. For example the SID1182KQ-TL, an 8 A/1200 V single channel IGBT/MOSFET gate driver.

SIC1182K is available in a 16-pin eSOP-R16B package. The combined connection of pins 3, 4, 5, and 6 on Power Integrations' SIC1182K isolated SiC gate driver provides a thermal path as well as a large number of primary-side ground connections

The SIC1182K incorporates short-circuit protection during the turn-on phase and overvoltage limiting at turn-off with advanced active clamping, all through a single sense pin. Isolated gate drivers require connections to primary/secondary side power and ground, logic control and drive outputs. Additional connections are provided for more powerful drivers. These include connections for logic fault signaling (open drain), sense inputs to detect short circuit events at turn-on and limit overvoltage at turn-off, bootstrap and charge pump supply voltages, and secondary side reference potentials .
The SIC1182K isolated SiC gate driver has added pins to increase the robustness of its drive function in a real circuit, which is always prone to failure and bad behavior.

Conclusion Viable EVs require advanced batteries as well as high-performance power management, both of which can be achieved through SiC] However, to realize the full potential of these high-performance SiC devices, designers must also select gate drivers appropriate to the application needs.