600 W TVS Ratings: Pulse Waveform, Temperature and Derating

Updated: October 28, 2026

This page is a focused engineering note in the tvs esd surge cluster—use the checklists and links below to finish selection, not as a substitute for the datasheet.

Topic hub: TVS diode selection guide. Related deep-dives sit in the continue list at the end.

Before release	Pass criteria
Ratings vs mission profile	Voltage/current/thermal margins recorded
Package & PCB	Rth path agreed with layout
Docs	Datasheet rev + PCN policy filed
Alternates	At least one workable second source or risk accepted

What 600 W Buys, and on Which Pulse

The 600 W label describes a defined transient test. It does not establish survival of every switching surge or connector discharge.

Vishay’s SMBJ series states its basis plainly: 600 W of peak pulse power capability on a 10/1000 µs waveform with a repetitive rate of 0.01 %, across 5.0 V to 188 V of standoff, in a low-profile SMB (DO-214AA) glass-passivated chip, unidirectional or bidirectional by the CA suffix, with moisture sensitivity level 1 at a 260 °C peak and AEC-Q101 qualified ordering codes.

STMicroelectronics’ SM6T covers the same class with a second basis attached: 600 W at 10/1000 µs and 4 kW at 8/20 µs, 5.8 V to 188 V standoff in its electrical-characteristics table, with leakage limits that depend on the ordering code, and up to 350 W of capability at the 150 °C maximum junction temperature. It also lists its standards coverage: IEC 61000-4-2 above level 4 at 30 kV air and contact discharge, and IEC 61000-4-4 level 4.

Parameter	Vishay SMBJ	ST SM6T
Peak pulse power	600 W at 10/1000 µs, 0.01 % duty cycle	600 W at 10/1000 µs; 4 kW at 8/20 µs
Capability at maximum junction temperature	Derated per the series curves	Up to 350 W at 150 °C
Standoff range	5.0 V to 188 V	5.8 V to 188 V in Table 2
Polarity	Unidirectional; CA suffix for bidirectional	Unidirectional; CA suffix for bidirectional
Leakage	Per part number at rated standoff	At each code’s rated standoff: SM6T12A/CA, 0.2 µA max at 25 °C and 1 µA max at 85 °C; SM6T6V8A/CA, 20 and 50 µA respectively
Package and assembly	SMB (DO-214AA), MSL 1, 260 °C peak, UL 94 V-0	SMB, MSL 1, JEDEC registered outline
Qualification or test scope	HE3 and HM3 AEC-Q101 qualified ordering codes	Listed device-level IEC 61000-4-2 and 4-4 tests; these do not establish AEC-Q101 qualification or a finished-system pass

The Three Rows That Cause Surprises

Start with the pulse definition, then check temperature and leakage.

The SMBJ waveform in Figure 3 rises in about 10 µs and decays to half peak current at the stated 1000 µs pulse width. The tail continues after that point. Multiplying 600 W by 1 ms gives 0.6 J for a hypothetical rectangular power pulse; it does not give a rated energy capacity for this decaying current waveform. Dissipated energy requires the voltage and current throughout the event: E = ∫v_TVS(t)i_TVS(t)dt.

Temperature and pulse duration change the permitted peak power. ST advertises up to 350 W at its maximum junction temperature; use its curves and exact part conditions rather than applying that headline universally. Leakage also varies by voltage code: SM6T Table 2 gives 20/50 µA limits for SM6T6V8A/CA at 25/85 °C, versus 0.2/1 µA for SM6T12A/CA at their respective standoff voltages.

For automotive procurement, check the full qualified ordering code. In Vishay’s SMBJ series, HE3 and HM3 identify AEC-Q101 options; an IEC transient-test statement describes a different test scope.

Where 600 W Is Enough, and Where It Is Not

Suitability follows the actual surge and protected circuit, rather than a universal boundary between power classes.

A 600 W-class device can be a candidate for short switching transients or the residual surge after an upstream suppressor. Check its standoff voltage against normal operation, its clamping voltage at the expected current against the protected node’s limit, and its derated pulse capability against the event. A larger 1500 W label alone does not prove a lower clamp voltage or compatibility with a longer pulse.

Load dump needs its own evaluation. TI’s SNOAAA1 application brief lists example 12 V Test A source parameters of 79–101 V, 0.5–4 Ω and 40–400 ms. Those ranges do not specify a fixed energy absorbed by every TVS. The clamp voltage, source waveform and impedance determine device current and dissipation. Where a data sheet does not cover the required pulse and repetition, select a device with the relevant characterization or evaluate an upstream clamp or active protection stage.

Keep power-class arithmetic separate from a series choice

The 600 W figure belongs to a stated pulse and temperature condition. Use this page to compare those conditions and the derating assumptions. For a device-level example with package, polarity, and rail selection, continue to the SMBJ guide.

Release checklist

• Re-read absolute maximum ratings against worst-case spikes.
• Confirm pinout/package drawing matches the footprint library.
• Capture why this MPN beat the next alternative (loss, cost, lead time, or qualification).

Selection checklist before you freeze the MPN

• Confirm working voltage (V_RWM) sits above the rail maximum including tolerance.
• Match surge waveform and peak pulse power (P_PPM) to the threat—not only the catalog wattage label.
• Check clamping voltage at the expected surge current against IC absolute-max ratings.
• For high-speed lines, verify capacitance and whether unidirectional or bidirectional polarity fits the signal.
• Re-check derating curves at your board temperature; catalog P_PPM is usually at 25 °C.

Ratings that decide real protection

Parameter	What to verify	Why it matters
VRWM	Above max continuous voltage	Avoids leakage and false clamping in normal operation
VC @ IPP	Below protected IC abs-max	Clamping too high still destroys the load
PPPM / waveform	8/20 µs vs 10/1000 µs as applicable	Watt labels are not interchangeable across pulses
Cj	Budget for USB/HDMI/RF integrity	Excess capacitance closes eyes on fast edges

FAQ

Unidirectional or bidirectional TVS—how do I choose?

Use unidirectional on DC rails with a defined polarity; use bidirectional on AC or reversible/signal lines where either polarity can appear.

Does a higher wattage TVS always protect better?

No. Clamping voltage, waveform rating, and layout often matter more than the wattage label alone.

Where should the TVS sit on the PCB?

At the entry connector with a short return to the surge ground—long stubs raise inductive overshoot.

Continue through this engineering topic

• TVS diode selection guide
• What is a TVS diode
• 1500w Tvs Protection Diode Reliable Surge Suppression for Power Electr
• 400 W vs 600 W Tvs Sizing the Pulse Energy
• Asmbj28ca 600 W Automotive Tvs in Smb for Lighting Drivers
• Choosing a Tvs for 24 V Inputs Industrial and Automotive

Topic hub: TVS diode selection guide — related selection guides and application notes in this cluster.