Automotive Chip Resistor Upgrade Path: 94,905 of 131,551 Walsin Commercial Part Numbers Have No Automotive Twin

The automotive chip resistor upgrade path exists for about a quarter of the catalogue. We matched every commercial part number against the automotive series across all 234,815 Walsin chip resistor rows. 36,646 of 131,551 commercial part numbers have an automotive twin. 94,905 do not, and eight of the fourteen series groups offer none at all.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 137 chip resistor export files published by Walsin Technology (Walsin) and both chip resistor datasheets. Our own cross-reference tool says it shows the commercial part first and lists the automotive version beneath it where one exists. This post measures where one exists, because that qualifier is doing more work than it looks like it is. Every part number below is real and every count is of part numbers, not pieces.

How many Walsin commercial chip resistors have an automotive twin at all?

36,646 of 131,551, which is 27.9%. We split all 234,401 distinct part numbers in Walsin’s published Walsin_ChipR_Product_Data export into the 102,850 that sit in a series naming “(Automotive)” and the 131,551 that do not, then tested every commercial code against the automotive set with one trailing character appended. 35,992 pair through a trailing J, 7,344 through V and 3,876 through Z, and some commercial codes pair more than one way.

	Part numbers
Distinct chip resistor part numbers	234,401
In a series named “(Automotive)”	102,850
Commercial	131,551
Commercial with an automotive twin	36,646
Commercial with no automotive twin	94,905

We have not seen this counted anywhere. The number a buyer needs is not how large the automotive range is — it is whether the specific part already on the board has a route into it, and for roughly seven commercial parts in ten the answer today is no.

Where does the upgrade path simply not exist?

In eight of the fourteen series groups, covering 24,819 commercial part numbers. We counted the twin rate group by group rather than taking a catalogue-wide average, because the average hides exactly the shelves an engineer most often needs.

Series Group	Commercial part numbers	With an automotive twin	Match / mismatch against the tool’s “where one exists”
Thick Film General Purpose	24,737	10,431	Match on 42% — the best-covered shelf
Thick Film High Power Chip Resistor	24,887	9,968	Match on 40%
High Precision Thick Film chip resistor	39,352	8,449	Mismatch on 79% — the largest gap in absolute terms
Thick Film High Voltage Chip Resistor	11,939	5,260	Match on 44%
Thick Film Low Ohm Current Sense	5,047	2,126	Match on 42%
Metal Low Ohm Current Sense	770	412	Match on 54% — the highest rate in the catalogue
Thick Film Anti-Surge Chip Resistor	8,340	0	Mismatch — no commercial anti-surge part has a twin
Thick Film Chip Resistor Array	5,864	0	Mismatch
Thick Film Wide Terminal Power	4,294	0	Mismatch
Thick Film Trimmable Chip Resistor	2,940	0	Mismatch
Thick Film Chip Resistor Array (Anti-Sulfuration)	2,772	0	Mismatch
Thick Film High Ohm Chip-Resistor (>10MΩ)	488	0	Mismatch
Thick Film Chip Resistor Network, Convex Type	98	0	Mismatch
Chip Attenuator (Convex, Π type)	23	0	Mismatch

Read the zero rows as a design constraint rather than a data complaint. WK12M1R0 XTL, a trimmable 1206 at 1.0 Ω, WK25L1R00FTL, a wide-terminal 1225 at 1.00 Ω and 2 W, and WF12G1105FTL, an 11 MΩ high-ohm part, are all real and all commercial. There is no same-code automotive version of any of them in this export. That does not mean nothing automotive will do the job; it means the swap is a different part, not a suffix, and it needs a real selection pass.

Those eight groups are not marginal. The anti-surge group holds 17,180 rows and 8,840 of them are automotive — they arrive under their own MK and MF codes rather than as twins. The series-group column says none of this; see Walsin chip resistor Series Group.

Are the twins that do exist identical on paper?

On seven published fields, 34,487 of the 36,646 are. We compared Size, Resistance, Tolerance, TCR, Rated Power, Packaging and Termination across every pair. 2,159 pairs differ on at least one field, which is 5.9% of the twins and the part of this that costs money if you assume it away.

What differs between the commercial part and its automotive twin	Pairs
Nothing, on all seven published fields	34,487
TCR only	990
Rated Power only	855
Both TCR and Rated Power	305
Resistance	9
Total differing	2,159

Of the 9 resistance differences, 7 are trailing-zero notation only — 0.04Ω against 0.040Ω on WW25NR040FTL and its twin WW25NR040FTLJ, and 0.510Ω against 0.51Ω on WW25WR510FTL, all of them in Metal_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx and Thick_Film_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx. The other 2 are genuine value disagreements in the metal plate shunt range, which we set out separately in chip resistor part number decoding.

Which way do the differences go?

Downward, on all 2,150 TCR and wattage cases we checked. The automotive twin is the looser or lower-rated part, never the tighter one. That is the opposite of the intuition most selectors are built on, and it is the single most useful thing in this post.

Commercial part	Automotive twin	Field that moves	Commercial	Automotive	Match / mismatch
WR06X1002FTL	WR06X1002FTLJ	none	0603, 10 kΩ, ±1%, ≦±100, 1/10 W	identical	Match on all seven fields
WR20X391 JTL	WR20X391 JTLJ	Rated Power	3/4 W	1/2 W	Mismatch — the automotive part is derated by a third
WR20X4420FTL	WR20X4420FTLJ	Rated Power	3/4 W	1/2 W	Mismatch — same derate at 442 Ω
WF10P3R57FTL	WF10P3R57FTLJ	TCR	≦±100 ppm/°C	≦±200 ppm/°C	Mismatch — drift doubles
WF06P6R80FTL	WF06P6R80FTLJ	TCR	≦±100 ppm/°C	≦±150 ppm/°C	Mismatch — drift up by half
WW25NR040FTL	WW25NR040FTLJ	Resistance notation	0.04 Ω	0.040 Ω	Match in value, mismatch in how it is written

A 2010 part derated from 3/4 W to 1/2 W is a 33% loss of headroom on a swap that looks like appending a letter, and a precision part whose TCR goes from ≦±100 to ≦±200 ppm/°C has doubled its drift budget. Both changes are published; neither is announced. This is why we publish mismatches rather than matches — the full argument is in second sourcing without re-qualifying.

How many automotive parts have no commercial starting point?

55,638 of 102,850, which is 54.1%. We tested the reverse direction too: strip the trailing character off each automotive code and see whether the remainder is a commercial part number. More than half the automotive range is not a suffixed version of anything — it arrives under its own prefixes, chiefly MR at 17,442 rows, SR at 12,871, MK at 3,030 and MA at 1,386.

Series Group	Automotive part numbers	With a commercial base code	Standalone
Thick Film General Purpose	50,891	20,236	30,655
Thick Film High Power Chip Resistor	14,954	9,968	4,986
High Precision Thick Film chip resistor	12,675	8,449	4,226
Thick Film Anti-Surge Chip Resistor	8,840	0	8,840
Thick Film High Voltage Chip Resistor	8,305	5,260	3,045
Thick Film Low Ohm Current Sense	5,381	2,887	2,494
Thick Film Chip Resistor Array	1,386	0	1,386
Metal Low Ohm Current Sense	418	412	6

The practical consequence is symmetrical. Going up from a commercial part, the suffix works 27.9% of the time. Coming down from an automotive part to find a commercial second source, the suffix works 45.9% of the time. In both directions the majority case is a real selection problem, and that is the job the free cross-reference tool is for — it matches on the fields, not on the string.

Does an automotive series name mean the part is AEC-Q200 qualified?

No, and the ten-column export says nothing about qualification at all. The only machine-readable automotive marker in 234,815 rows is the word “(Automotive)” inside the free-text Series string, on 17 of the 58 series. There is no AEC-Q200 column, no grade column and no qualification-status column anywhere in the schema.

We hold a chip resistor datasheet for two of the thirteen part-number prefixes: MR, 10 pages, and WR, which is ASC_WR_V24 dated September 2016. We hold no public URL for either file, so we cite the filename. The 12,871-part SR anti-sulfuration automotive series — one of the two largest automotive resistor prefixes in the catalogue — has no sheet in our 451 pages, and we say so rather than let you find out during supplier approval. For what the designation does and does not cover, see what AEC-Q200 actually certifies.

What should you ask for before you plan the swap?

Three things, in this order, and all three are answerable in a day against the 137 export files and the 451 datasheet pages we hold. We will tell you what we do not hold — 11 of the 13 chip resistor prefixes have no page at all — which is the part nobody else puts in writing.

1. Cross the whole list in one pass. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool, filter by commercial or automotive grade, and read every stated difference. It decodes 18 manufacturers’ part numbers against 800,000+ crossable Walsin part numbers, and where an automotive version exists it is listed beneath the commercial one with the differences shown rather than hidden.
2. Check what is physically in Hong Kong on ready stock — 1,125 part numbers as at 23 September 2026, a dated snapshot and not a live feed. The trade press reported passive component lead times stretching through 2026 as AI server and vehicle electrification programmes drew on the same capacity, so a dated list you can read beats a promise you cannot.
3. Ask for the governing document and the qualification report by part number. We hold 28 Walsin datasheets, 451 pages, and two of them are chip resistor sheets. Where there is no page covering your part, you get that answer the same day.

Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong. (852) 2628 4777. Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation. The range sits on the Walsin chip resistor page.

The short version

36,646 of Walsin’s 131,551 commercial chip resistor part numbers have an automotive twin formed by one trailing character; 94,905 do not. Eight of the fourteen series groups offer no twin for any commercial part — 24,819 part numbers between them. Of the twins that exist, 34,487 are identical on all seven published fields and 2,159 are not: 990 differ on TCR, 855 on rated power, 305 on both and 9 on resistance, and in every TCR and wattage case the automotive part is the looser or lower-rated one. Going the other way, 55,638 of 102,850 automotive part numbers have no commercial base code at all. We will not tell you a part is a drop-in. We will show you the field that moved and by how much. Qualification stays with you.

Send us the resistor lines you need to take to automotive grade and we will return, for each one, whether a twin exists, which of the seven fields moves if it does, and which document governs it. And a question back: on the last grade upgrade you signed off, did anyone check the wattage, or did the suffix do the checking?

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Frequently asked questions

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