In power electronics, temperature is rarely where the simulation says it will be. Inverters, DC link stages, and compact transmission control modules run hotter than the spreadsheet predicted, especially once the enclosure is sealed and the airflow is theoretical. That is where small sensing parts begin to struggle. TDK has extended its NTCSP series of automotive NTC thermistors to survive ambient conditions up to 175 C, which quietly shifts where these sensors can sit inside modern power modules without becoming the weak link.
Why 175 C Matters Inside Today’s Power Modules
Automotive power semiconductors have been climbing in junction temperature for years. SiC devices in particular are comfortable at levels that would have made older silicon IGBTs nervous. The surrounding ecosystem has had to follow. A thermistor that topped out at 150 C might still function electrically, but qualification margins disappear quickly once the module housing creeps higher during sustained load. By extending guaranteed operation to 175 C, the NTCSP series aligns more closely with the thermal reality around traction inverters, engine control zones, and high current transmission electronics. This is not about chasing a headline number. It is about allowing the temperature sensor to remain physically closer to the heat source without derating gymnastics.
The devices are qualified to AEC Q200, which means the usual battery of automotive stress tests applies. Thermal cycling, mechanical shock, humidity bias. None of that is glamorous, but in a brake controller or engine bay assembly, it is the difference between a stable calibration curve and a service bulletin.
AgPd Terminations and the Move Away from Solder Limits
One of the more interesting decisions here is the adoption of silver palladium terminations designed for conductive glue mounting. Traditional solder joints start to look less comfortable as continuous temperatures approach the upper edge of their rating. You can specify high temperature solder alloys, but process windows tighten and long term reliability modeling becomes more cautious. Conductive adhesive changes that equation slightly.
Using AgPd terminals compatible with conductive glue allows the thermistor to tolerate sustained 175 C environments that would be awkward for conventional solder mounting. That does not remove assembly considerations. Conductive adhesive introduces its own process controls, curing profiles, and contact resistance behavior. But it does let designers rethink placement inside densely packed power stages where local board temperature is no longer polite.
Electrical Characteristics in a 1.6 x 0.8 mm Footprint
The NTCSP parts are offered in a 1.6 x 0.8 mm package, so these are genuinely compact sensors rather than leaded beads hiding elsewhere on the PCB. Two resistance options are available at 25 C, 10 kΩ and 100 kΩ, each with a 1 percent resistance tolerance. The 10 kΩ version carries a B constant around 3435 K measured between 25 and 85 C, while the 100 kΩ variant sits higher, near 4485 K, also with tight tolerance.
That B constant spread matters more than it first appears. A higher B value sharpens the resistance change across temperature, which can help resolution in certain compensation networks, but it also alters linearization strategies in firmware. Designers already comfortable with 10 kΩ NTC curves will need to check lookup tables and ADC scaling if migrating between variants. The operating range from minus 55 C up to 175 C covers both cold start conditions and prolonged high load operation, which is not trivial when you consider how wide automotive duty cycles really are.
Where These Sensors Actually Sit in the Vehicle
TDK positions the series for ABS modules, transmissions, and engine related electronics. In practice, the interesting applications are often inside hybrid and EV power control units where board level temperature monitoring feeds derating algorithms. The sensor may not be measuring junction temperature directly, but it provides a proxy close enough to prevent runaway conditions.
As thermal envelopes continue to stretch upward, the humble NTC has to keep pace. It is not a glamorous component, and it will never be the hero of a system block diagram. But once ambient temperatures push beyond what older mounting approaches tolerated, small construction details such as terminal metallurgy and adhesive compatibility start to matter more than the nominal resistance printed in the datasheet.
Learn more and read the original announcement at www.tdk.com
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