SMCJ TVS Diodes: Package, Clamping and Device Selection

SMCJ is not a rating but a class: a 1500 W transient voltage suppressor in a DO-214AB (SMC) body. Bourns’ series covers 5.0 V to 495 V of standoff, a 200 A.

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SMCJ TVS Diodes: Package, Clamping and Device Selection

SMCJ is not a rating but a class: a 1500 W transient voltage suppressor in a DO-214AB (SMC) body. Bourns’ series covers 5.0 V to 495 V of standoff, a 200 A peak forward surge current and 5 W of steady-state dissipation at a 75 °C lead temperature, and those three numbers, not the headline figure, are what tell you whether it fits a design.

Last updated: October 16, 2026

Reading the 1500 W Rating Correctly

A peak pulse power rating is meaningless without its waveform, and the SMCJ class is a good place to see why.

Bourns’ SMCJ data sheet states 1500 W minimum peak pulse power dissipation at a 1 ms pulse, with the note that the value is non-repetitive and must be derated above a 25 °C ambient. ST’s SM15T — the same 1500 W class from another vendor — quotes 1500 W for a 10/1000 µs waveform, up to 10 kW for an 8/20 µs waveform, and states plainly that capability falls to about 1250 W at its 150 °C maximum junction temperature.

Those three statements are consistent, and together they describe the shape of a TVS: the shorter and steeper the pulse, the more power the die can take; the hotter the junction, the less it can take. A selection made from the headline number alone therefore assumes the mildest condition in the datasheet.

Parameter	Bourns SMCJ series	ST SM15T series
Peak pulse power	1500 W minimum at T_P = 1 ms	1500 W at 10/1000 µs; up to 10 kW at 8/20 µs
Standoff voltage range	5.0 V to 495 V (breakdown to 550 V)	5 V to 188 V
Surge current	200 A (8.3 ms single half sine, unidirectional)	Per part number at the rated pulse
Steady-state dissipation	5.0 W at T_L = 75 °C	Not specified as a DC rating
Forward voltage at I_PP = 100 A	3.5 V (5.0 V to 90 V parts), 5.0 V (100 V to 495 V parts)	Per part number
Leakage	Per part number at rated standoff	0.2 µA at 25 °C
Junction temperature	−55 °C to +150 °C	150 °C maximum
Package	DO-214AB (SMC)	SMC

Selecting One, in Order

Four steps, and each one can eliminate a part number before the next matters. Set the standoff above the highest normal operating voltage including tolerance, so the device stays off in service. Then take the clamping voltage at the peak pulse current the circuit can present and check it against the absolute maximum of everything downstream. Then compare the pulse energy with the class rating above. Finally, confirm the mechanical and qualification details: the SMC body, the unidirectional or bidirectional configuration, and — for automotive programmes — an AEC-Q101 qualified variant such as the HE3 or HM3 ordering codes on the Vishay SMBJ series, or the equivalent qualification route from other vendors.

The reverse of that order is where projects get stuck: choosing by the 1500 W headline and discovering at validation that the clamping voltage at the real surge current sits above the supply’s absolute maximum, or that the energy is two orders of magnitude beyond the class.

Check the package and clamping entry together

For an SMCJ candidate, confirm its package outline, polarity suffix, maximum operating rail voltage, and clamping result at the stated test current. A power-class label does not establish the protected circuit’s margin. Use the 1500 W pulse-energy guide for the separate waveform and protection-coordination discussion.

FAQ

What is an SMCJ TVS diode?

It is a transient voltage suppressor in the DO-214AB (SMC) surface-mount package, built around a 1500 W peak pulse power class. Bourns’ series covers 5.0 V to 495 V of standoff voltage with unidirectional and bidirectional options.

What does the 1500 W rating actually mean?

It is peak pulse power for a defined waveform. Bourns specifies 1500 W at a 1 ms pulse, derated above 25 °C; ST’s SM15T quotes 1500 W at 10/1000 µs and up to 10 kW at 8/20 µs, falling to about 1250 W at maximum junction temperature.

Can an SMCJ TVS handle an automotive load dump?

Not unsuppressed. An ISO 16750-2 test A load dump is a 40 ms to 400 ms event worth hundreds of joules, while a 1500 W part is rated for roughly 1.5 J in a single millisecond-class pulse. It fits the shorter transients, or a bus that already has central suppression.

How do I choose between SMCJ and SMBJ?

By the energy of the event and the room for the package. SMBJ is the 600 W class in a DO-214AA body; SMCJ is the 1500 W class in the larger DO-214AB. Move up a class when the surge energy or the required clamping margin does not fit the smaller part.

What should be checked before approving a TVS part number?

The standoff against the maximum normal voltage, the clamping voltage at the actual surge current against the downstream absolute maximum, the pulse energy against the class rating, the leakage at temperature, and the qualification variants available for the target market.

Official Resources

References

Bourns, SMCJ Transient Voltage Suppressor Diode Series — source of the 1500 W minimum peak pulse power at 1 ms, the 5.0 V to 495 V standoff range with breakdown to 550 V, the 200 A 8.3 ms surge current, 5.0 W steady-state dissipation at a 75 °C lead temperature, the forward voltages at 100 A, the −55 °C to +150 °C range and the DO-214AB (SMC) package. bourns.com — SMCJ series datasheet (PDF)
STMicroelectronics, SM15TxxA, SM15TxxCA — 1500 W TVS in SMC — source of the 1500 W (10/1000 µs) and up to 10 kW (8/20 µs) ratings, the 5 V to 188 V standoff range, 0.2 µA leakage, 1250 W at maximum junction temperature and the 150 °C limit. st.com — SM15T series datasheet (PDF)
Vishay, SMBJ5.0A thru SMBJ188A, document 88392 — the 600 W class used for the SMBJ-versus-SMCJ comparison, including the AEC-Q101 ordering codes. vishay.com — SMBJ datasheet (PDF)
Texas Instruments, Protection against Unsuppressed Load Dump in Automotive Systems, SNOAAA1 — source of the ISO 16750-2 test A pulse parameters (79 V to 101 V, 0.5 Ω to 4 Ω, 40 ms to 400 ms for a 12 V system) used in the energy comparison. ti.com — unsuppressed load dump application brief (PDF)

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For the complete selection, design, verification, and troubleshooting path, explore the TVS ESD and Surge Protection Hub.