The automotive marker is in the series name and nowhere else. 102,995 of the 234,815 chip
resistor rows Walsin Technology (Walsin) publishes — 43.9% — carry “(Automotive)” in the
Series field. There is no automotive column, no AEC-Q200 column, and no character in the part
number that says automotive across the whole catalogue. Filter on the series text or you will
mix grades.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 137 of Walsin’s
chip resistor export files and both Walsin chip resistor datasheets. This post is written from
those. Every part number below is real. Counts are of part numbers, not pieces.
How do you tell a Walsin automotive chip resistor from a commercial one?
By reading the Series text. All 137 export files share one ten-column schema — Part Number,
Series Group, Series, Size, Resistance, Tolerance, TCR, Rated Power, Packaging, Termination.
None of those columns is a qualification flag. “(Automotive)” appears as a suffix inside the
Series string, and that string is the only machine-readable marker in the data.
Across the extract that marker falls on 18 series in 9 of the 14 series groups:
| Series group | Automotive series | Automotive parts |
|---|---|---|
| Thick Film General Purpose | 4 | 50,891 |
| Thick Film High Power | 1 | 15,099 |
| High Precision Thick Film | 2 | 12,675 |
| Thick Film High Voltage | 2 | 8,305 |
| Thick Film Anti-Surge | 2 | 8,840 |
| Thick Film Low Ohm Current Sense | 2 | 5,381 |
| Thick Film Chip Resistor Array | 2 | 1,386 |
| Metal Low Ohm Current Sense | 2 | 418 |
| Total | 18 | 102,995 rows / 102,850 distinct part numbers |
One thing the data does get right: no part number sits in both an automotive and a
non-automotive series. We checked all 234,815 rows — the overlap between the 102,850 automotive
part numbers and the 131,551 non-automotive ones is zero. The split is real. It is simply
recorded in free text instead of a field you can tick.
What are the MR, SR and WR prefixes?
Three prefixes share the Thick Film General Purpose group’s 75,628 parts, and only two of them
are wholly automotive.
| Prefix | Parts | Series it covers | Automotive? |
|---|---|---|---|
MR |
17,442 | General Purpose (Automotive) 13,566; General Purpose LF 100ppm (Automotive) 3,876 | All 17,442 |
SR |
12,871 | High Grade Anti-Sulfuration Chip Resistor (Automotive) 12,871 | All 12,871 |
WR |
45,315 | General Purpose 15,047; General Purpose LF 100ppm 9,690; General Purpose (Automotive) 9,919; General Purpose Anti-Sulfuration (Automotive) 10,659 | 20,578 of 45,315 |
So MR and SR are safe prefix tests for automotive within this group. WR is not: 24,737
of its 45,315 parts are commercial. A buyer who filters the general purpose group on WR
gets a 45% / 55% mixture of automotive and commercial parts with no warning.
What separates an automotive WR part from a commercial one is the packaging suffix, not the
prefix:
| Suffix | Series | Grade |
|---|---|---|
TL |
General Purpose | Commercial |
TR |
General Purpose LF 100ppm | Commercial |
TLJ |
General Purpose (Automotive) | Automotive |
TLV, TLZ |
General Purpose Anti-Sulfuration (Automotive) | Automotive |
On MR and SR the same suffixes mean something else again. MR...TL and MR...TLV are
both General Purpose (Automotive); MR...TR is the LF 100ppm automotive series. SR...TL and
SR...TLW are both High Grade Anti-Sulfuration (Automotive). The suffix is not a grade code
across the whole group — it is a variant code whose meaning depends on the prefix.
What does one 0603 10 kΩ 1% line look like across all three prefixes?
Ten real part numbers, across three prefixes and five series. Every one is 0603, 10 kΩ, ±1%,
≦±100 ppm/°C. Nine of the ten are automotive.
| Part number | Series | Rated power | Match / mismatch |
|---|---|---|---|
WR06X1002FTL |
General Purpose | 1/10 W | Mismatch — the only commercial part here |
WR06X1002FTR |
General Purpose LF 100ppm | 1/10 W | Mismatch — commercial |
WR06X1002FTLJ |
General Purpose (Automotive) | 1/10 W | Automotive |
WR06X1002FTLV |
General Purpose Anti-Sulfuration (Automotive) | 1/10 W | Automotive + sulfur resistant |
WR06X1002FTLZ |
General Purpose Anti-Sulfuration (Automotive) | 1/10 W | Automotive + sulfur resistant |
MR06X1002FTL |
General Purpose (Automotive) | 1/8 W | Mismatch on rated power — see below |
MR06X1002FTLV |
General Purpose (Automotive) | 1/10 W | Automotive |
MR06X1002FTR |
General Purpose LF 100ppm (Automotive) | 1/10 W | Automotive |
SR06X1002FTL |
High Grade Anti-Sulfuration (Automotive) | 1/10 W | Automotive, high grade sulfur |
SR06X1002FTLW |
High Grade Anti-Sulfuration (Automotive) | 1/10 W | Automotive, high grade sulfur |
Five of the five selection fields an engineer normally ticks — size, resistance, tolerance, TCR
and rated power — are identical on nine of these ten parts. The tenth differs in rated power
alone. Nothing in those five fields tells you which are automotive and which are not.
Is the MR automotive part rated for more power than the WR commercial part?
Yes, at three of the four shared case sizes. This surprises people, because the automotive part
is usually assumed to be the more conservative one. Both datasheets tabulate maximum
dissipation at 70 °C ambient:
| Case size | MR automotive | WR general purpose | Match / mismatch |
|---|---|---|---|
| 1210 (3225) | 1/2 W | not in the WR datasheet | Mismatch — MR only |
| 1206 (3216) | 1/4 W | 1/4 W | Match |
| 0805 (2012) | 1/4 W | 1/8 W | Mismatch — MR one step higher |
| 0603 (1608) | 1/8 W | 1/10 W | Mismatch — MR one step higher |
| 0402 (1005) | 1/10 W | 1/16 W | Mismatch — MR one step higher |
Source: Walsin_MR_Automotive_Thick_Film_Chip_Resistor.pdf page 3 and
Walsin_WR_General_Purpose_Chip_Resistor.pdf page 3, both held on file by Venatech.
Maximum operation voltage and maximum overload voltage are identical across both series —
200 V, 150 V, 75 V and 50 V operating at 1206, 0805, 0603 and 0402, and double those figures
on overload. Climatic category is 55/155/56 on both. The MR series adds a stated operating
range of −55 to +155 °C, anti-sulfuration to ASTM B-809 at 60 °C for 500 hours, and 100% CCD
inspection; the WR datasheet states none of those.
The TCR tables also diverge, and not in the direction you would expect. The MR datasheet
breaks TCR into three resistance bands and publishes ±200 ppm/°C above 1 MΩ. The WR datasheet
publishes a single ±100 ppm/°C band for everything above 10 Ω. So on paper the commercial
series claims a tighter high-ohm TCR than the automotive one. The parametric export follows
the datasheets: 2,995 MR rows carry ≦±200 and 15,851 WR rows carry ≦±200, because the WR
prefix also covers high-ohm parts the WR datasheet does not tabulate.
Why do some MR parts contradict the MR datasheet?
Because the rated power in the export tracks the packaging suffix, and on three case sizes the
TLV and TR variants carry the WR figure instead of the MR figure.
| Case size | MR datasheet | MR…TL export |
MR…TLV and MR…TR export |
Match / mismatch |
|---|---|---|---|---|
| 0402 (1005) | 1/10 W | 1/10 W | 1/16 W | Mismatch on 1,938 parts |
| 0603 (1608) | 1/8 W | 1/8 W | 1/10 W | Mismatch on 1,938 parts |
| 0805 (2012) | 1/4 W | 1/4 W | 1/8 W | Mismatch on 1,938 parts |
| 1206 (3216) | 1/4 W | 1/4 W | 1/4 W | Match |
| 1210 (3225) | 1/2 W | 1/2 W | 1/2 W | Match |
That is 5,814 MR automotive part numbers exported at a rated power one step below Walsin’s
own MR datasheet — and in every case the figure they carry is exactly the WR general purpose
rating for the same case size. MR04X1001FTL and MR04X1001FTLV are the same series name,
the same 1 kΩ, the same ±1%, the same ≦±100 ppm/°C, one character apart, and they are exported
at 1/10 W and 1/16 W.
We have not seen this documented anywhere. The pattern is consistent enough to look like a
copy-down from the WR element data rather than a real derating, but we cannot confirm that.
Which MR case sizes has Walsin not published a datasheet for?
Four of the nine. The MR datasheet we hold covers MR04, MR06, MR08, MR10 and MR12 — 0402, 0603,
0805, 1210 and 1206. The export carries four more case sizes with no datasheet coverage at all:
| Case size in the export | MR rows | In the MR datasheet? |
|---|---|---|
| 0402 (1005) | 2,907 | Yes, MR04 |
| 0603 (1608) | 2,907 | Yes, MR06 |
| 0805 (2012) | 2,907 | Yes, MR08 |
| 1206 (3216) | 2,907 | Yes, MR12 |
| 1210 (3225) | 1,938 | Yes, MR10 |
| 0201 (0603) | 969 | No |
| 1218 (3248) | 969 | No |
| 2010 (5025) | 969 | No |
| 2512 (6432) | 969 | No |
3,876 of 17,442 MR parts — 22.2% — sit outside the datasheet we hold. For those, the export’s
rated power is the only published figure, and the voltage and TCR tables that would let you
check it do not exist in anything we have. Ask before you design one in.
Does Walsin say these parts are AEC-Q200 certified?
The MR datasheet uses the word compliant, not certified. Its cover page reads “Automotive &
Military Compliant” and its feature list reads “Automotive AEC Q-200 & Military MIL-STD
Compliant”. Those are Walsin’s words for Walsin’s parts, and compliant is not the same claim as
holding a qualification report for the specific part number, case size and resistance you are
buying.
So the practical step is the same one you would take with any manufacturer: ask for the
AEC-Q200 qualification report covering the exact part number, and check the revision date
against the datasheet revision. We will request it from Walsin for any MR, SR or automotive WR
part. Venatech makes no AEC-Q200 claim of its own — the qualification belongs to the
manufacturer, and the document is the only thing worth relying on.
For what the standard does and does not certify, see
What AEC-Q200 actually certifies. For the same
prefix problem on the MLCC side, see
AEC-Q200 MLCC: MT vs MG series. The full range is on the
Walsin chip resistor range page.
The short version
Read the series text, not the prefix. MR and SR are wholly automotive; WR is 45%
automotive and the suffix is what tells you which. Expect the MR part to be rated higher than
the WR part in the same case size, not lower. Treat the rated power on MR…TLV and MR…TR
parts as unresolved. And for the 3,876 MR parts outside the datasheet, get the specification
in writing before the design review.
Send us your automotive BOM and we will tell you, line by line, which series each position
sits in and whether a datasheet exists for it. Or give us one part number and ask us to
cross it.
Faster than an email. The cross-reference tool takes a pasted list or a spreadsheet and returns Walsin chip resistor candidates field by field, differences included. Ready stock shows what is physically in Hong Kong, so you can see straight away whether a line is a stock pull or a production slot.
Frequently asked questions
How many of Walsin’s chip resistors are automotive grade?
102,995 of 234,815 rows in Walsin’s parametric export — 43.9% — carry “(Automotive)” in the Series field, across 18 series in 9 series groups. That is 102,850 distinct part numbers. No part number appears in both an automotive and a non-automotive series.
What is the difference between Walsin MR and WR chip resistors?
MR is the automotive general purpose series and WR covers both commercial and automotive general purpose parts. MR is rated one power step higher than WR at 0402, 0603 and 0805, adds a 1210 case size, and its datasheet states anti-sulfuration to ASTM B-809, 100% CCD inspection and −55 to +155 °C operation. Operating and overload voltages are identical.
Is there an AEC-Q200 column in Walsin’s resistor data?
No. All 137 chip resistor export files share one ten-column schema and none of the columns is a qualification flag. The only automotive marker is the “(Automotive)” text inside the Series string, so any filter has to be a string match on that field.
What does the SR prefix mean on a Walsin resistor?
High Grade Anti-Sulfuration Chip Resistor (Automotive). All 12,871 SR parts in the thick film general purpose group belong to that one series, across seven case sizes from 0402 to 2512. All 12,871 SR parts are automotive, so the prefix is a safe test within this group; WR is not.
Can I filter Walsin’s general purpose resistors on the WR prefix to find automotive parts?
No. 24,737 of the 45,315 WR parts are commercial and 20,578 are automotive. Within WR the automotive parts carry the suffixes TLJ, TLV or TLZ, and the commercial parts carry TL or TR. Filtering on the prefix alone mixes the two grades.
Why does the same MR part number family show two different rated powers?
Because the export’s rated power tracks the packaging suffix. At 0402, 0603 and 0805 the MR…TL parts carry the MR datasheet figure and the MR…TLV and MR…TR parts carry the WR general purpose figure, one step lower. That affects 5,814 part numbers. Venatech has flagged it for written confirmation from Walsin and does not recommend designing to either figure until it is resolved.
Does Walsin publish a datasheet for every MR case size?
No. The MR datasheet covers 0402, 0603, 0805, 1206 and 1210. The export also lists MR parts at 0201, 1218, 2010 and 2512 — 3,876 part numbers, 22.2% of the MR line — with no datasheet coverage in anything Venatech holds. For those, request the specification from Walsin before design-in.
Is a Walsin automotive resistor AEC-Q200 certified or AEC-Q200 compliant?
Walsin’s MR datasheet says “Automotive AEC Q-200 & Military MIL-STD Compliant”. Compliant is not the same as holding a qualification report for your exact part number. Ask for the report and check its revision date against the datasheet revision. Venatech will request it from Walsin and makes no qualification claim of its own.