Automotive Current Sense Resistor WW PR: 647 Plain-TL Parts, Three Sizes With No Commercial Twin, and 191 Specifications That Differ at 0805

The Walsin WW PR automotive current sense resistor has no commercial twin at 1210, 2010 or 2512. We parsed all 4,348 PR rows: 1,943 sit at those three sizes, in the automotive series only, and 647 of them carry no automotive letter. Where both grades exist, 191 of 761 specifications differ, all at 0805.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the Walsin Technology (Walsin) thick film current sense export, Thick_Film_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx. This post reads one type code in it, the PR in WW08PR100FTL, in both the commercial and the automotive series, and compares them specification by specification. Every part number below is real. The suffix letters J and V are decoded in the suffix post, already published, and we do not repeat that work here.

Does Walsin sell the WW PR current sense resistor in the same sizes in both grades?

In four of seven sizes. We counted every PR row by series name and case size: 869 commercial rows at 0402, 0603, 0805 and 1206, and 3,479 automotive rows at those four plus 1210, 2010 and 2512. The three larger sizes hold 1,943 rows, 44.7 percent of the automotive PR range, and none has a commercial PR twin.

A specification here is one case size, one resistance and one tolerance. We have not seen this counted anywhere. The commercial PR series simply stops at 1206, so a design that uses WW25PR at 2 W in an automotive board cannot be prototyped from a commercial part of the same code.

How many automotive PR specifications have no commercial twin?

655 of 1,416, or 46.3 percent. We grouped the PR rows into specifications: 869 commercial, 1,416 automotive. 761 exist in both grades, 655 exist only in the automotive series and 108 exist only in the commercial series. The 655 are 648 at 1210, 2010 and 2512 and 7 at the shared sizes (6 at 0402, 1 at 0805).

The 108 commercial-only specifications are 36 at each of 0402, 0603 and 0805, and they run the other way: a commercial part exists and an automotive one does not. Both directions matter for a grade swap, and the wider catalogue picture, 94,905 of 131,551 commercial chip resistor part numbers with no automotive twin, is in the upgrade-path post.

Are the PR specifications that exist in both grades identical on paper?

570 of 761 are, and the 191 that are not all sit at 0805. At 0805 the commercial PR is rated 1/3 W with a TCR of ≦±150; the automotive PR is rated 1/4 W with ≦±200. That is 75 percent of the power and a TCR one third looser, on 191 of 191 shared 0805 specifications. At 0402, 0603 and 1206 every shared specification matches on rated power and TCR.

The export carries no other differing field: Size, Resistance, Tolerance, Packaging and Termination agree on every shared specification. A designer who moves from WW08PR100FTL to its automotive twin on the strength of a matching stem loses a quarter of the power rating and 50 ppm per degree Celsius. The power-rating angle of that same 0805 position is in one value, five type codes.

What is a plain TL part doing inside the automotive series?

It is the automotive series’ unflagged variant, and there are 647 of them. At 0402 to 1206 every automotive PR specification has two part numbers, one ending TLJ and one TLV; at 1210, 2010 and 2512, 647 specifications have a third, ending plain TL, with no automotive letter, listed under the series name that carries (Automotive). Each TL row is 647 of the 1,943 at those three sizes.

This is the largest part of a count we published earlier. The suffix post found that a trailing-letter rule for automotive misses 977 current sense rows; we can now break them down: 647 are PR rows at 1210, 2010 and 2512, and the other 330 are WR rows with a different tail. A decoder that reads the last letter to detect automotive grade will label every one of the 647 as commercial while the export files them in the automotive series.

We do not say which reading is right. The export gives the series name and the letters; it does not say whether the plain TL parts are qualified in the same way as the J and V parts. Ask Walsin for the qualification report against the exact part number, which is the standing advice in AEC-Q200 compliant is not certified.

What does the whole automotive PR ladder look like at one value?

One value, seven sizes, a power ladder that doubles at the top. At 0.100 ohm, ±1 percent, the automotive PR range runs 1/8 W at 0402 and 0603, 1/4 W at 0805, 1/2 W at 1206 and 1210, 1 W at 2010 and 2 W at 2512, while the TCR ceiling tightens from ≦±300 to ≦±150 by 1206. The commercial PR range stops at 1/2 W.

Note that 1210 adds nothing over 1206 in power: both carry 1/2 W in the automotive PR range, which is the pattern behind our count of rows out-rated by a smaller case, in chip resistor case size and power rating.

What should you ask for before moving a PR design to the automotive grade?

Three documents, and a stem check. We hold 28 Walsin datasheets, 451 pages, and two are chip resistor sheets, WR general purpose and MR automotive; neither covers the WW current sense series, so the 4,348 PR rows are the export’s figures and nothing more. Walsin’s own wording for the automotive grade is compliant with AEC-Q200, not certified, and Venatech makes no qualification claim of its own.

1. The datasheet for the exact part number, including rated power and TCR at its case size. At 0805 the two grades differ.
2. The qualification report for the exact part number, not for the series name, and not for the J or V neighbour if you are buying the plain TL.
3. The full part number with its suffix, pasted without trimming. Any stem comparison that drops the suffix cannot see the 191 differences.

The free cross-reference tool lists the field differences between your part and each Walsin candidate; paste your incumbent into the blank column above and compare. What sits in Hong Kong is on ready stock: 1,125 part numbers as at 23 September 2026, a dated snapshot and not a live feed. The wider range is on the chip resistor page, and the split between automotive and commercial resistor lines is in MR, SR and the AEC-Q200 split.

The short version

The Walsin WW PR current sense resistor is not one family in two grades. We parsed 4,348 PR rows. Four sizes exist in both grades; 1210, 2010 and 2512 exist only in the automotive series, 1,943 rows, and 647 of those carry no automotive letter. Of 761 specifications in both grades, 570 match on rated power and TCR, and the 191 that do not are every shared one at 0805: 1/3 W and ≦±150 against 1/4 W and ≦±200. We will not tell you the grades are interchangeable. We will show you the fields the export holds. Qualification stays with you.

Send us the current sense positions on your BOM with the grade each needs, and we will list for each one the Walsin PR part numbers in both series and the field that moves between them. And a question back: when you last swapped a commercial current sense part for its automotive twin, did you compare the rated power or only the stem?

Frequently asked questions