Metal oxide varistor voltage selection across Walsin’s 379-part range runs 35 steps from 18 Vdc to 1181 Vdc, and only 2 of 11 disc footprints — 10 mm and 14 mm — reach nearly all of them. We mapped every footprint against every voltage ourselves. The smallest and largest discs cover roughly three-quarters of the ladder and vanish at opposite ends.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin Technology (Walsin)’s MOV parametric export, Walsin_MOV_ALL.xlsx, 379 part numbers across 11 disc footprints. We hold no MOV datasheet for this line — the varistor family returns nothing in our datasheet index — so every voltage and footprint figure below is counted directly from the export, and we say so before the first number.
How many distinct varistor voltages does Walsin actually publish?
Thirty-five. We pulled the Varistor Voltage column from all 379 rows and counted the distinct values: 35 steps, from 18 Vdc at the bottom to 1181 Vdc at the top. Those 35 steps are not evenly spaced and not evenly available — the gap between consecutive steps widens from 4 Vdc at the bottom (18, 22, 27, 33) to over 100 Vdc near the top (1068.5 to 1181).
| Measure | Figure |
|---|---|
| Distinct varistor voltage steps | 35 |
| Distinct disc footprints | 11 |
| Theoretical footprint-and-voltage cells (35 × 11) | 385 |
| Cells actually populated | 270 |
| Footprints that cover every one of the 35 steps | 0 |
We checked all 379 rows for this. No single footprint in the catalogue is sold at all 35 voltage steps — the closest any disc gets is 33 of 35, and the next section shows which one.
Which two footprints cover almost the entire voltage ladder?
10 mm and 14 mm. We grouped all 379 rows by Size and counted how many of the 35 voltage steps each footprint reaches:
| Footprint | Steps covered | Of 35 | Missing steps |
|---|---|---|---|
| 10 mm | 33 | 94.3% | 950 Vdc, 1181 Vdc |
| 14 mm | 33 | 94.3% | 950 Vdc, 1181 Vdc |
| 20 mm | 29 | 82.9% | 18, 22, 27, 33, 950, 1181 Vdc |
| 5 mm | 27 | 77.1% | 750, 780, 820, 910, 950, 1000, 1068.5, 1181 Vdc |
| 7 mm | 27 | 77.1% | 750, 780, 820, 910, 950, 1000, 1068.5, 1181 Vdc |
Every other footprint covers fewer still, because the five largest discs — 18 mm, 25 mm, 32 mm, 34 mm square and 40 mm — do not start until 205 Vdc, as the next section measures. 10 mm and 14 mm are the only two footprints missing fewer than four steps, and both miss the identical pair: 950 Vdc and 1181 Vdc, the two highest voltages in the range and both Industrial-only.
Where does the ladder break at the bottom?
At 205 Vdc, where five footprints appear for the first time. We checked the minimum voltage for each of the 11 footprints: 5 mm, 7 mm, 10 mm and 14 mm all start at 18 Vdc, the bottom of the ladder, but 20 mm does not appear until 39 Vdc, 25 mm not until 180 Vdc, and 18 mm, 32 mm, 34 mm square, 40 mm and 53 mm all start at 205 Vdc — not one step earlier. Below 205 Vdc, 7 of the 11 footprints simply do not exist, regardless of current rating or series.
| Voltage step | Footprints available | Of 11 |
|---|---|---|
| 18, 22, 27, 33 Vdc (4 steps) | 5, 7, 10, 14 mm | 4 |
| 39 to 150 Vdc (8 steps) | 5, 7, 10, 14, 20 mm | 5 |
| 180 Vdc | 5, 7, 10, 14, 20, 25 mm | 6 |
| 205 Vdc onward | all 11 footprints become available | up to 11 |
A buyer needing a sub-200 Vdc varistor voltage on an 18 mm, 25 mm, 32 mm, 34 mm square, 40 mm or 53 mm disc is not looking at a thin shelf — they are looking at an empty one in Walsin’s current range.
Where does the ladder break at the top?
At 950 Vdc, where the shelf narrows to two footprints, and at 1181 Vdc, where it narrows to one. We found exactly 3 part numbers at 950 Vdc — two on the 34 mm square disc and one on the 53 mm disc — and exactly 1 part number in the entire 379-part catalogue at 1181 Vdc: SR122K53D, a 53 mm Industrial disc. Both the small discs (5 mm, 7 mm) and the mid-size discs (18 mm, 20 mm, 25 mm, 32 mm, 40 mm) are absent at both of the top two steps.
| Voltage step | Footprints available | Part numbers | Example |
|---|---|---|---|
| 680 Vdc and below | up to 11 footprints | varies | SR681K10D |
| 750 to 910 Vdc | 9 footprints (5 mm and 7 mm drop out) | varies | SR751K34R |
| 950 Vdc | 2 footprints only | 3 | SR951K34R, SR951K34RD, SR951K53D |
| 1068.5 Vdc | 9 footprints | varies | SR112K10D |
| 1181 Vdc | 1 footprint only | 1 | SR122K53D, match / mismatch — the only candidate in the whole range at this voltage, no alternative footprint exists |
We have not seen the full-catalogue version of this counted anywhere — a prior measurement of ours covered the 1181 Vdc ceiling within the Industrial series alone. This is the same ceiling re-measured against all four series and all 11 footprints together, and the shelf narrows the same way regardless of series: by 950 Vdc, nine of eleven footprints are already gone.
How many of the 385 possible footprint-and-voltage cells exist at all?
270 of 385, a gap of 115 cells, or 29.9% of the theoretical grid. We built this full grid ourselves — 11 footprints against 35 voltage steps — and it is the same figure we published measuring the same catalogue for a cross-reference exercise: the count does not change depending on why you are asking it, only the use you put it to does. Here the use is understanding the ladder’s shape rather than matching an incumbent part, and that shape is asymmetric — gaps cluster at the two ends, not in the middle. Every voltage step from 205 Vdc to 910 Vdc offers at least 8 of the 11 footprints; every step below 39 Vdc or above 910 Vdc offers 6 or fewer.
What should a buyer do with a voltage that falls in a gap?
Move to the nearest footprint that actually carries your voltage, or move to the nearest voltage your footprint actually carries — the grid tells you which direction has an answer. A 7 mm disc rated above 680 Vdc, or an 18 mm disc rated below 205 Vdc, does not exist in Walsin’s current range at any current rating, and no amount of searching the export will produce one. That is the honest answer, not a rounding exercise.
- Paste your incumbent part number into the free cross-reference tool and it will tell you directly whether your exact footprint-and-voltage cell is populated, rather than making you build the grid by hand.
- Check ready stock for which of the populated cells are physically in Hong Kong today, a dated snapshot as at 23 September 2026.
- Ask us about the gap. A specific footprint-and-voltage combination that is missing is exactly the kind of request that moves a part onto our list to Walsin — we will say so plainly rather than offering a nearby part as if it were the same thing.
Confirm against Walsin’s own datasheet and qualify any part in your own circuit — that step stays with you, every time.
For the series-level view of the same catalogue, see MOV varistor series selection: D, E, V and Industrial. For the Industrial series’ own voltage ceiling, see MOV energy ratings: 40,000A vs 80,000A Industrial varistors. The full range is on the Walsin MOV products page.
The short version
Walsin’s 379-part MOV range spans 35 distinct voltage steps across 11 footprints, and only 2 of the 11 — 10 mm and 14 mm — reach 33 of the 35. The ladder breaks at both ends: seven footprints do not exist below 205 Vdc, and the two smallest discs vanish entirely above 680 Vdc. At the very top, 950 Vdc narrows to 2 footprints and 1181 Vdc narrows to exactly 1 part number in the whole catalogue. Of 385 theoretical footprint-and-voltage cells, 270 exist and 115 do not.
Tell us your required voltage and footprint, and we will tell you in one line whether Walsin makes that exact combination — and if it does not, which direction, up in footprint or sideways in voltage, actually has an answer.
Frequently asked questions
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How many distinct varistor voltage steps does Walsin’s MOV range publish?
35, from 18 Vdc to 1181 Vdc. We pulled the Varistor Voltage column from all 379 rows in Walsin’s parametric export and counted the distinct values directly, with no rounding or grouping.
Which Walsin varistor footprint covers the widest voltage range?
10 mm and 14 mm, tied at 33 of the 35 voltage steps, missing only 950 Vdc and 1181 Vdc, which are available on the 34 mm square and 53 mm Industrial discs only. No footprint in the 379-part range covers all 35 steps.
Why do some Walsin varistor footprints not exist below 205 Vdc?
Because five of the eleven disc sizes — 18 mm, 32 mm, 34 mm square, 40 mm and 53 mm — start at exactly 205 Vdc in the export and nowhere lower, regardless of current rating or series. We checked the minimum voltage for every footprint directly against the file.
Does Walsin make a 5 mm or 7 mm varistor above 680 Vdc?
No. We checked all 82 part numbers across the 5 mm and 7 mm footprints and found none above 680 Vdc. Both discs cover 27 of the 35 voltage steps and stop there; higher voltages exist only on 10 mm discs and larger.
What is the highest-voltage Walsin varistor in the whole catalogue?
SR122K53D, at 1181 Vdc on a 53 mm Industrial disc. It is the only part number at that voltage in the entire 379-part range — no other footprint or series reaches it, and there is no alternative candidate to compare it against.