The Onsemi SiC Gamble Amidst the EV Demand Plateau
As 2025 unfolds, a growing sentiment suggests that onsemi's SiC business is not expanding as the market anticipated. The SiC business, built primarily around EV inverters, faces headwinds from a slowdown in electrification pace in Europe and the US, leading to a series of downward revisions to annual forecasts. However, the company remains steadfast in its SiC investment strategy. This report examines the rationale behind this "staying the course" decision through the lenses of technology, market, and competition.
Why SiC Investment Continues Despite EV Slowdown
With EV manufacturers adjusting production, power semiconductor companies have encountered accumulating SiC inventory and order deferrals. Onsemi is no exception, experiencing a deceleration in SiC-related revenue growth from the latter half of 2024 into 2025. Viewed in isolation, this might be described as a "correction phase in the SiC boom."
Yet, the scale of development and manufacturing investments under its EliteSiC brand has not diminished. This resilience stems from a deliberate shift toward a business structure that diversifies beyond sole reliance on the EV sector. The portfolio, encompassing SiC MOSFETs and diodes from 650V to 1700V, along with modules, is designed for expansion beyond EV inverters into industrial equipment and renewable energy applications.
This strategy suggests an effort to establish a framework where sales in the industrial and energy infrastructure sectors can provide a stable floor, even if EV demand temporarily wanes. Nevertheless, verifying the actual effectiveness of this strategy will be crucial as segment-specific revenue breakdowns are disclosed.
What Defines the EliteSiC Technology Position?
When discussing the merits of SiC devices, low on-resistance (RDS(on)) is often highlighted. While it's a critical metric for loss reduction, "short-circuit withstand time (SCWT)" serves as another crucial axis that influences actual system reliability. SCWT refers to the duration a device can withstand a load short circuit before failure, essentially providing a grace period before protective circuits activate.
Short-circuit withstand time and low on-resistance are fundamentally in a trade-off relationship. Reducing on-resistance typically involves miniaturizing the die and increasing current density, leading to faster temperature rises during a short circuit. SiC devices, inherently smaller and with higher current densities than silicon, tend to exacerbate this issue. Consequently, protective circuits may need to be designed with faster response times for SiC compared to silicon.
Short-Circuit Withstand Time (SCWT)
The grace period before protective circuits operate. It depends on drain voltage, gate voltage, and junction temperature conditions, with varying minimum requirements for different systems.
On-Resistance (RDS(on))
A direct indicator of conduction loss. It has a trade-off with short-circuit withstand time; the priority depends on the application's usage.
Compatibility with DESAT Protection
If the DESAT detection parameters (threshold voltage and blanking time) on the gate driver side are not aligned with the device's short-circuit withstand capability, there's a risk that protection may not activate in time.
Temperature Dependency
SiC MOSFETs tend to increase RDSon at higher temperatures, suppressing saturation current, while short-circuit withstand time generally improves at higher temperatures. Evaluation across the operating temperature range is essential.
Achieving both short-circuit withstand time and on-resistance requires delving into the device structure itself. Rohm's 4th-generation SiC MOSFETs and Mitsubishi Electric's trench SiC-MOSFETs with a p-type protective layer are frequently cited industry examples attempting to balance these through structural improvements. Onsemi's EliteSiC also aligns with a similar direction, positioning enhanced system reliability through high efficiency as a competitive advantage. Examining how effectively each approach improves these metrics, by comparing datasheet conditions, can provide valuable insights.
Short-Circuit Protection Circuit Design and Device Selection are Inseparable
The complexity of SiC lies in its inability to isolate technical discussions to the device alone. Specifically, short-circuit protection design only functions effectively when the device's specifications and the gate driver's settings work in concert.
DESAT (desaturation) protection monitors the on-state drain-source voltage (VDS) and turns off the switch upon detecting overcurrent. Key parameters for its operating speed include the DESAT trigger threshold (VDESAT), DESAT current (IDESAT), and short-circuit blanking time.
For Microchip's 1200V SiC MOSFETs, the nominal short-circuit withstand time under specific conditions is typically stated as 3μs. This 3μs indicates the maximum time the protective circuit has to switch off the device before it fails. If the gate driver's DESAT response time exceeds this, protection will not be established, even if it operates according to its specifications. When selecting a device, it's crucial to recognize that examining the short-circuit withstand time value alone is insufficient; verification must include the timing design of the gate driver to assess the safety margin in practical use.
Drain Voltage (VDS)
Lowering this reduces short-circuit power density, extending SCWT. This provides material for re-examining the relationship between operating points and protection response.
Gate Voltage (VGS)
Reducing VGS lowers saturation current and shifts towards withstand capability, but this creates a trade-off with increased Ron.
Junction Temperature (Tj)
A characteristic tendency of SiC is that at higher temperatures, RDSon increases, limiting saturation current, while short-circuit withstand capability tends to improve (opposite to Si IGBTs). This characteristic needs to be understood.
While the chart above illustrates directional trends rather than precise figures, it serves to organize the understanding that short-circuit withstand time is not a single fixed value but fluctuates with operating conditions. In actual designs, the short-circuit withstand time under worst-case conditions (such as high drain voltage, high gate voltage, or during cold starts) becomes the bottleneck for system safety design.
How Does onsemi Differentiate from Competitors? Measuring EliteSiC's Position
In the SiC market, onsemi faces a diverse array of competitors, including Infineon with its CoolSiC series, STMicroelectronics, Rohm, and Mitsubishi Electric. Amidst competitors with distinct strengths in scale, technology, and supply chain, understanding the axes along which EliteSiC differentiates itself is vital for assessing business sustainability.
Onsemi EliteSiC
Promotes low loss and high efficiency as enhancements to system reliability. Offers a full portfolio from 650V to 1700V, bridging industrial, EV, and energy applications.
Infineon CoolSiC
Focuses on achieving low RDSon with trench MOSFETs. Offers reference designs combined with gate driver ICs to accelerate design cycles.
Rohm 4th Generation SiC
Differentiates itself through proprietary structures that achieve both low RonA and high short-circuit withstand capability. Continues to expand its range of automotive-qualified products.
Mitsubishi Electric Trench SiC
Significantly improves short-circuit withstand capability with the introduction of a p-type protective layer. Emphasizes the completeness of module products and holds a strong position in high-capacity inverters.
One of onsemi's distinguishing features is its positioning of products not as standalone devices but within the context of portfolio breadth and system-level efficiency improvements. EliteSiC's emphasis on "high efficiency and improved system reliability through low power loss" can be interpreted as an intention to move beyond discrete specification comparisons and encourage evaluation on the grounds of total cost of ownership (TCO).
Conversely, the extent to which this proposition influences procurement decisions varies with the stage of power system development. In the later stages of mass production, the availability of certified devices and supply stability carry significant weight. In the early development phase, the quality of data available for efficiency simulations plays a role in the decision-making process. The perception of EliteSiC's competitiveness will thus vary depending on the evaluation phase.
How to Interpret the Current Situation
While no one can definitively predict when the EV demand plateau will end, the adoption of SiC itself is not receding. Applications in industrial equipment, solar, and energy storage systems are quietly expanding, and the non-automotive SiC market is emerging as a stabilizing force for business across multiple manufacturers.
Technologically, the challenge of balancing short-circuit withstand time and on-resistance is becoming a central theme in the development of 4th and 5th-generation devices. Including the issue of system integration with gate drivers, the "difficulty of mastering SiC" will persist even as devices advance. Manufacturers and distributors capable of providing support with a deep understanding of this complexity may gain an advantage as long-term partners.
Onsemi's decision to continue SiC investments at this juncture will be validated by the recovery in electrification in 2026 and beyond, as well as by its performance in the industrial sector. At present, tracking the specific adoption achievements the company is accumulating across various applications and technological axes remains the most reliable way to evaluate this business.