Find the snap-back TVS for the part you already designed in.
Type any competitor suppressor part number. We read the stand-off voltage out of the number and match it to the AMSEMI foldback band, then print the full three-point window — VRWM, VBR, VC at IPP — so you can run it through your own derating rules instead of trusting a shopping cart.
01The full window, all twelve bands
Every row is a real part with a datasheet behind it. The last column is the only number that matters when you are trying to keep a MOSFET inside its rating: how far the clamp sits below a standard suppressor of the same stand-off and the same peak pulse current.
| AMSEMI part | VRWM | VBR min–max (V) | VC at IPP (V) | IPP (A) | Standard VC (V) | Clamp delta |
|---|---|---|---|---|---|---|
| Waveform: all clamp voltages and peak pulse currents at 10/1000 µs, non-repetitive. Standard VC: conventional 5.0SMDJ of the same stand-off, same waveform, same IPP — same die, same test, not a cross-vendor guess. Bands we do not stock as standard parts carry the published 5.0SMDJ figure for that stand-off; the sheet goes out with the quote so you can check the row yourself. Package: DO-214AB (SMC) throughout. Grade: industrial in stock; AEC-Q101 built to order (suffix -H, lead time and price confirmed per order). | ||||||
02How the match is made
We would rather tell you what this tool does than let you assume it is an official equivalence table. It is not. Here is the exact rule set.
The number in your part number is the stand-off
SMCJ54CA → 54 V stand-off. 5.0SMDJ85A → 85 V. The suffix tells us polarity, the prefix tells us power class, and the digits tell us the band. We match on the band.
If your number does not land on one of our twelve bands, we say so and point at the nearest one — we do not silently round you onto a part.
Up is fine, down is not
SMCJ (1.5 kW), SMDJ (3 kW), 5.0SMDJ (5 kW) and 8.0SMDJ (8 kW) are all DO-214AB. Moving up a power class at the same stand-off keeps the footprint and drops the clamp — that is the whole point.
Moving down is a die-size decision, not a catalogue decision. Ask before you do it.
CA, A, and what changes
The foldback family is bidirectional (CA). A bidirectional part is normally fine on a DC rail and clamps both ways, but it is not a drop-in on a polarity-critical or AC-coupled line.
Two dies instead of one also means roughly twice the junction capacitance — check Cj against your signal bandwidth, not against the datasheet headline.
03Why the clamp number decides the BOM
A 48 V rail, a 100 V MOSFET, and the 80% derating most design rules apply to VDS. That leaves the switch 80 V of usable rating. This is where a standard suppressor stops working and a foldback one still does.
Standard 5.0SMDJ54CA clamps at 87.1 V
87.1 V is above the 80 V derated ceiling of a 100 V MOSFET. To survive it you move up to a 150 V device — more RDS(on), more cost, more board area, or a different gate driver.
The suppressor did its job and still forced a BOM change. That is the normal outcome engineers accept without questioning it.
5.0SMDJ54CA-N clamps at 69.6 V
69.6 V sits inside the 80 V ceiling with room left for the tolerance stack. The 100 V MOSFET stays, the driver stays, the layout stays.
Same footprint, same 57.5 A peak pulse current, same 10/1000 µs test. The only thing that changed is where the clamp lands.
04Questions we get on quote calls
What replaces a Littelfuse SMCJ54CA or a Vishay SMCJ54CA?
Does a snap-back TVS replace a standard TVS pin-for-pin?
Can a foldback TVS protect a 100 V MOSFET on a 48 V bus?
5.0SMDJ54CA-N clamps at 69.6 V and clears it with 10.4 V spare. If you are already running a 150 V MOSFET to survive the clamp, the swap is what lets you come back down.