Varistor Cross Reference for Germany: 115 of 385 Walsin MOV Footprint-Voltage Cells Are Empty

A varistor cross reference from a Bourns or Littelfuse family to Walsin MOV works on footprint and voltage first, and 115 of the 385 possible combinations in Walsin’s own 379-part range do not exist. We built the full grid ourselves. For a buyer in Germany replacing a disc-type varistor, roughly three cells in ten return nothing before peak current is even compared.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin Technology (Walsin)’s MOV parametric export, Walsin_MOV_ALL.xlsx, 379 part numbers, no duplicates. We hold no Bourns or Littelfuse data file and no Walsin MOV datasheet of any kind — this post teaches the crossing method and puts only Walsin’s own measured data in the table, with a blank column for your incumbent part. Every part number below is real and checked against our own master part list.

What does crossing a Bourns or Littelfuse varistor family to Walsin MOV actually mean?

Matching footprint and voltage before anything else, because those two fields decide whether a candidate exists at all. Bourns and Littelfuse both sell radial disc varistors in the same industry-standard diameters Walsin uses — 5, 7, 10, 14, 20 and 25 mm at the small end, larger discs for industrial surge duty — so the first question is never “which part is equivalent,” it is “does Walsin make a disc this size at this voltage.” We will not call any part equivalent. We will show you, field by field, where it matches and where it does not.

How many of Walsin’s footprint-and-voltage combinations exist at all?

Fewer than a full grid would suggest. We built an 11-footprint by 35-voltage grid from Walsin_MOV_ALL.xlsx — 385 possible cells — and counted how many actually hold a real part number. 270 cells are populated and 115 are empty, a 29.9% gap. Of the 270 that exist, 161 hold exactly one Walsin part number and 109 hold two, because a second series (High Energy, Super High Energy, or a second Industrial current grade) sits at the identical footprint and voltage.

Measure	Count	Share of 385
Footprint-and-voltage cells with zero Walsin parts	115	29.9%
Cells with exactly one Walsin candidate	161	41.8%
Cells with two Walsin candidates (series overlap)	109	28.3%

We have not seen this counted anywhere. A cross-reference attempted purely on footprint and nominal voltage — the two fields a datasheet-blind search engine matches first — fails outright on close to a third of the grid, before peak current, tolerance or disc thickness are compared at all.

Which footprint and voltage match the common 275V European mains rating?

Seventeen Walsin part numbers, across all four series, at one voltage point. The disc-type varistor rating most familiar to a German mains-surge design is the 275 Vac working-voltage class, which Walsin publishes at 430 Vdc varistor voltage. We pulled every row at that exact voltage from Walsin_MOV_ALL.xlsx and list all seventeen, leaving the last column for your incumbent part number.

Walsin part number	Series	Footprint	Peak current	Your incumbent part (fill in)
SR431K05D	Standard (D)	5 mm	400 A	—
SR431K07D	Standard (D)	7 mm	1,200 A	—
SR431K10D	Standard (D)	10 mm	2,500 A	—
SR431K14D	Standard (D)	14 mm	4,500 A	—
SR431K20D	Standard (D)	20 mm	6,500 A	—
SR431K25D	Standard (D)	25 mm	18,000 A	—
SR431K05E	High Energy (E)	5 mm	800 A	—
SR431K07E	High Energy (E)	7 mm	1,750 A	—
SR431K18E	High Energy (E)	18 mm	9,000 A	—
SR431K10E	Super High Energy (V)	10 mm	4,000 A	—
SR431K14E	Super High Energy (V)	14 mm	8,000 A	—
SR431K20E	Super High Energy (V)	20 mm	13,000 A	—
SR431K32D	Industrial	32 mm	30,000 A	—
SR431K34R	Industrial	34 mm square	40,000 A	Match / mismatch vs your incumbent — same footprint class, confirm peak current and disc thickness yourself
SR431K34RD	Industrial	34 mm square	80,000 A	Match / mismatch vs your incumbent — same footprint, double the current of SR431K34R
SR431K40D	Industrial	40 mm	40,000 A	Match / mismatch vs your incumbent — different footprint, same current as SR431K34R
SR431K53D	Industrial	53 mm	70,000 A	Match / mismatch vs your incumbent — largest footprint at this voltage

This is the single widest voltage point in the catalogue: 17 of Walsin’s 379 parts sit at 430 Vdc, spread across all 11 footprints and all four series. Not every voltage point is this generous — the next section shows why.

Does the part number suffix tell you which Walsin series you are matching?

No, not on its own, and this is the trap a blind cross hits first. We checked all 108 parts Walsin labels High Energy (E Series) and Super High Energy (V Series): every single one ends in the letter E. SR431K05E is a 5 mm High Energy part rated 800 A; SR431K10E is a 10 mm Super High Energy part rated 4,000 A. The two-digit footprint code — 05 against 10 — is the only thing in the string that tells them apart; the trailing letter does not. A cross tool matching on suffix alone will merge two series with different current ratings into one bucket.

The Industrial series carries a parallel trap on its 34 mm square discs: 34R is rated 40,000 A and 34RD is rated 80,000 A at the identical footprint and voltage, so a last-character split groups the 80,000 A part with every other part ending in D regardless of current. Read the full footprint code, then the series name Walsin assigns in its own Series column, never the trailing character alone.

What happens when your incumbent footprint has no Walsin candidate?

You have found one of the 115 empty cells, and the honest answer is that no Walsin part exists there — not that one is close enough to call equivalent. We deliberately did not round or interpolate when building the grid above: a footprint-and-voltage pair either has a real part number in Walsin_MOV_ALL.xlsx or it does not. The small discs are the first place this bites — 5 mm and 7 mm parts stop entirely above 680 Vdc in our extract, so an incumbent 5 mm part rated above that voltage has no Walsin match at that footprint at any current rating, full stop.

In that case the real options are a different footprint at the same voltage, a different voltage point nearby, or a written request to Walsin for a part that is not yet in the parametric export. We will tell you which of the three applies to your exact incumbent rather than guessing.

What should a varistor buyer in Germany do with this?

Cross the exact footprint and voltage first, series and current second, and treat any gap as a gap rather than a rounding error. Lead times on passive surge-protection components have been reported stretching through 2026 across the trade press, alongside the same AI-server and EV capacity pressure affecting MLCCs and inductors, so identifying a second source fast matters whether or not Walsin’s grid has a cell at your exact rating.

1. Paste your Bourns or Littelfuse part number into the free cross-reference tool. It decodes 18 manufacturers’ part numbers and matches against 800,000+ crossable Walsin part numbers, returning the footprint and voltage match (or the honest absence of one) field by field.
2. Check ready stock for which varistor part numbers are physically in Hong Kong, as a dated snapshot at 23 September 2026, not a live feed.
3. Ask us for the series your grid cell is missing. We hold no Walsin MOV datasheet today; a specific request is what puts a part on our list to Walsin rather than leaving the gap unresolved.

Confirm against both datasheets — yours and, once we obtain it, Walsin’s — and qualify any crossed part in your own circuit before it goes into a design.

For the series-by-series current comparison, see MOV varistor series selection: D, E, V and Industrial. For a European market already measured this way, see Varistor selection for Poland: appliance and industrial volume. The full range is on the Walsin MOV products page.

The short version

A varistor cross reference from Bourns or Littelfuse to Walsin MOV turns on footprint and voltage before anything else, and 115 of the 385 combinations we measured do not exist as a real Walsin part. Where a cell is populated, 161 of 270 offer one candidate and 109 offer two, because a higher-energy series sits at the same footprint and voltage. The part number suffix will not tell you which series you are looking at — the footprint code and the Series column will.

Send us your Bourns or Littelfuse varistor part number and we will tell you, footprint by footprint, whether a Walsin cell exists at that rating — and if it does not, whether an adjacent footprint or voltage does. Qualification stays with you.

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Frequently asked questions

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