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STMicroelectronics SM4T14CAY — Circuit Protection

STMicroelectronics SM4T14CAY TVS Diode, AEC-Q101, 400W

MPNSM4T14CAY
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STMicroelectronics SM4T14CAY, Automotive AEC-Q101 TRANSIL™ bidirectional TVS diode, 12V reverse standoff, 25.3V clamp, 400W peak pulse power, DO-214AC SMA package.

$0.6000Ref. price · indicative, final on quote
STMicroelectronics SM4T14CAY datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

SM4T14CAY specifications
ParameterValue
TypeZener
SeriesAutomotive, AEC-Q101, SM4TY, TRANSIL™
MountingSurface Mount
Voltage - breakdown13.3V
Voltage - clamping (Max) @ ipp25.3V
Voltage - reverse standoff12V
Current - peak pulse (10/1000μs)91A (8/20µs)
Power - peak pulse400W
Power line protectionNo
Operating temperature-55°C~150°C(TJ)
PackageTape & Reel (TR); Cut Tape (CT)
ApplicationsAutomotive
CaseDO-214AC, SMA
Bidirectional channels1

Product details

12V automotive rail protection — the SM4T14CAY

The STMicroelectronics SM4T14CAY is a bidirectional TRANSIL™ TVS diode qualified to AEC-Q101. It clamps overvoltage spikes on 12V DC power rails in automotive electronic modules.

The reverse standoff voltage is 12V, meaning the diode will not conduct appreciably below that rail voltage — it stays invisible to the 12V bus during normal operation. Breakdown occurs at a minimum of 13.3V, and the clamping voltage at the peak pulse current of 91A (8/20 µs waveform) is 25.3V. That 25.3V clamp is what the downstream circuitry must survive; if the protected IC's absolute-maximum input is, say, 30V, there is margin.

Housed in a DO-214AC (SMA) surface-mount package, the SM4T14CAY shares the same footprint as many other SMA-packaged TVS diodes. The wide temperature range also suits outdoor telecom and industrial 12V rails that see thermal cycling.

For production BOMs, this means no immediate obsolescence risk. For dual-sourcing resilience, the SM4T14 series includes multiple voltage variants sharing the same SMA footprint, but within the 12V bidirectional option the SM4T14CAY is the standard order code.

Frequently asked questions

Is SM4T14CAY automotive grade?

Yes, the SM4T14CAY is part of the Automotive SM4TY series and is qualified to AEC-Q101, the stress-test qualification standard for discrete semiconductors used in automotive applications. This means it has passed the required reliability tests for under-hood and cabin electronics.

What is the difference between SM4T14CAY and SM4T14AY?

The 'C' in SM4T14CAY denotes a bidirectional device — it clamps both positive and negative transients with a single component. The SM4T14AY (without the 'C') is a unidirectional version, which only clamps in one polarity and requires correct orientation on the board. For AC-coupled or bipolar transient protection on a 12V rail, the bidirectional CAY variant simplifies layout and avoids reverse-installation errors.

Is SM4T14CAY suitable for 12V automotive systems?

Yes. With a 12V reverse standoff voltage, the SM4T14CAY is specifically rated for nominal 12V DC rails. It will not conduct at the normal 12V bus voltage, but will begin clamping above 13.3V, protecting downstream electronics from load-dump and other transients up to 25.3V at the peak pulse current. This matches the protection requirements for automotive 12V electronic control units (ECUs), sensors, and infotainment modules.