ROHM Puts 1.55 V IGBTs Into EV Compressors and Heaters
ROHM's 4th-generation 650 V automotive IGBTs claim a 1.55 V typical saturation voltage and 7 microsecond short-circuit withstand, aimed at EV compressors, cabin heaters and industrial inverters.
ROHM has released a 4th-generation automotive-grade 650 V IGBT family with a typical collector-emitter saturation voltage of 1.55 V and a 7 microsecond short-circuit withstand time, targeted at EV electric compressors, PTC and coolant high-voltage heaters, and industrial inverters.
ROHM has launched a fourth generation of 650-volt IGBTs built to automotive qualification standards, aimed squarely at the parts of an electric vehicle that most buyers never think about: the electric air-conditioning compressor, the high-voltage cabin and battery heaters, and the industrial inverters that share the same silicon.
The headline numbers are two. The typical collector-emitter saturation voltage, VCE(sat), is 1.55 V. And the short-circuit withstand time is 7 microseconds at junction temperature. Both are the figures a thermal-system designer looks at first, and both are worth translating.
What VCE(sat) and short-circuit withstand actually buy you
An IGBT — insulated-gate bipolar transistor — is a power switch. It turns high-voltage direct current on and off tens of thousands of times a second so an inverter can synthesise the alternating current a motor needs, or so a heater can be modulated smoothly rather than banged fully on and off.
VCE(sat) is the voltage dropped across the device while it is switched on. That drop, multiplied by the current flowing, is heat. Heat has to go somewhere, and in a compressor module that means a heatsink, thermal interface material, sometimes a coolant loop. A lower saturation voltage is therefore not an abstract spec sheet win: it is fewer watts to dissipate, which is a smaller heatsink, a lighter module, a cheaper enclosure, and — because the compressor and heater draw off the traction battery — marginally more range for the same pack.
Short-circuit withstand time is the safety margin. If the output shorts, the device has to survive long enough for the gate driver's protection circuit to detect the fault and shut it down. Seven microseconds is short in human terms and generous in silicon terms; it is the window in which the protection logic has to do its job. Designers trade this against conduction loss, because the design choices that make a device tougher under fault usually make it lossier in normal running. Claiming a low VCE(sat) alongside a stated withstand time is the whole pitch.
Compressors and heaters are the overlooked half of EV electronics
Most attention in EV power semiconductors goes to the traction inverter, where silicon carbide has taken the premium end of the market. The auxiliary systems are a different problem. They run at lower power, they run constantly rather than in bursts, and they are brutally cost-sensitive — which is exactly the territory where a well-optimised silicon IGBT still beats wide-bandgap alternatives on price per switched watt.
Cabin and battery heating in particular has become a competitive battleground. PTC heaters — positive temperature coefficient resistive elements, which self-limit as they warm — and coolant heaters that warm a liquid loop both draw directly from the high-voltage bus. In cold weather they are one of the largest non-traction loads in the car, and a meaningful cause of the winter range collapse that shows up in owner complaints. Efficiency in the switching stage is one of the few levers available without adding pack capacity.
ROHM is also pointing the same parts at industrial equipment inverters, which matters commercially. Automotive qualification is expensive; amortising it across an industrial line spreads the cost and gives the product a second demand curve that does not move with EV sales.
Silicon still has a job in a wide-bandgap world
The strategic read here is that IGBTs are not being displaced everywhere at once. Silicon carbide wins where switching frequency and peak efficiency justify a premium — the main drive inverter, the onboard charger. Below that, the older technology keeps improving generation on generation, and each improvement pushes the crossover point where SiC pays for itself a little further up the power curve.
The strategic read here is that IGBTs are not being displaced everywhere at once.
For suppliers, that is a rational hedge. A company selling both can let the customer choose, and the auxiliary-systems socket is high-volume: every EV has a compressor, and in cold markets essentially every EV has a high-voltage heater. Content per vehicle is modest compared with a traction inverter, but the attach rate is close to universal.
The release was reported by Charged EVs.
What the tape says about the backdrop
The announcement lands into a broadly firm equity market. As of the last trade at 20:00 GMT on 2 September 2026, the S&P 500 tracker (NYSEARCA: SPY) stood at $765.20, up 0.45% on the day from a previous close of $761.78, with a session range of $761.73 to $766.43. The Nasdaq 100 fund (NASDAQ: QQQ) was at $709.31, up 0.24%, and the Dow 30 fund (NYSEARCA: DIA) at $530.62, up 0.54%.
Component launches of this kind rarely move a share price on the day, and this one carries no revenue guidance, no customer name and no volume-production date. Its significance is cumulative: design wins in auxiliary power electronics are sticky, because requalifying a switch inside a compressor module is not something an automaker does casually mid-programme.
What to watch from here
- Whether module makers rather than automakers are the first named adopters — compressors are usually bought as complete units, so the design-in happens a tier down the supply chain.
- Package and current-rating variants, which determine whether the family reaches beyond compressors and heaters into other auxiliary loads.
- How rival power-semiconductor suppliers respond on the same two metrics, since VCE(sat) and short-circuit withstand time are the numbers this segment competes on publicly.
- Cold-climate range data, the ultimate real-world test of whether heater-side efficiency gains show up where drivers notice them.
None of this resolves quickly. Automotive power semiconductor cycles run in years, from sampling through qualification to volume. But the direction is clear enough: the efficiency fight in electric vehicles has moved past the motor, into the thermal system, and the switches inside it are now being marketed on decimal points of saturation voltage.
Key facts
- Device: ROHM 4th-generation automotive-grade 650 V IGBTs
- Typical VCE(sat): 1.55 V
- Short-circuit withstand: 7 µs at junction temperature
- Market backdrop: SPY $765.20, +0.45%, as of 20:00 GMT, 2 Sep 2026
Frequently asked questions
What is an IGBT and why does an EV need one?
An insulated-gate bipolar transistor is a high-voltage power switch. It rapidly turns direct current on and off so an inverter can drive a motor or modulate a heater. In an electric vehicle, IGBTs sit inside the air-conditioning compressor drive and the high-voltage heaters, controlling power drawn straight from the traction battery.
What does a 1.55 V saturation voltage mean in practice?
Collector-emitter saturation voltage is the voltage lost across the switch while it is conducting. Multiplied by current, it becomes waste heat. ROHM quotes a typical VCE(sat) of 1.55 V for these parts. A lower figure means less heat to remove, allowing smaller heatsinks, lighter modules and slightly less energy drawn from the battery pack.
Why does short-circuit withstand time matter?
If the output shorts, the transistor must survive long enough for the gate driver's protection circuitry to detect the fault and switch it off. ROHM specifies 7 microseconds at junction temperature for this family. That window defines how fast the surrounding protection electronics have to react to prevent destructive failure of the device.
Which applications is ROHM targeting?
Three named areas: electric compressors in EV air-conditioning systems, high-voltage heaters of both the PTC resistive type and the coolant-loop type, and inverters for industrial equipment. The industrial application matters commercially because it spreads the cost of automotive qualification across a second market with different demand cycles.
Why use silicon IGBTs rather than silicon carbide?
Silicon carbide dominates where peak efficiency and high switching frequency justify a premium, typically the traction inverter and onboard charger. Auxiliary loads such as compressors and heaters run at lower power and are far more cost-sensitive, so improved silicon IGBTs remain competitive there on price per switched watt.
Does this announcement include financial details?
No. The release covers device specifications and target applications only. There is no stated volume-production date, no named customer, no pricing and no revenue guidance. Design wins in automotive power electronics typically take years to move from sampling through qualification to volume shipment, so any commercial impact would emerge gradually.
Sources
Photo: Marta Branco · Pexels Licence — source
