Current Sense Resistor TCR: Zero of Walsin’s 10,428 Thick Film Parts Reach ±50 ppm/°C

We parsed all 10,428 rows of Walsin’s thick film low-ohm current sense export. Not one reaches ±50 ppm/°C. Current sense resistor TCR is the field that decides your measurement error over temperature, and on thick film the shelf stops at ±100 ppm. On metal plate, 612 of 1,188 rows reach ±50.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds all 203 of Walsin Technology (Walsin) parametric export files and 28 Walsin datasheets. This post is measured from two of those files — Thick_Film_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx and Metal_Low_Ohm_Current_Sense_Chip_Resistor__1of1.xlsx — and every part number below is real. Every count is of part numbers, not pieces.

How low does Walsin’s thick film current sense TCR actually go?

To ±100 ppm/°C, and no further. We checked all 10,428 thick film rows: 1,501 reach ±100 ppm/°C, and zero reach ±50. The metal plate and metal foil file behaves differently — 1,187 of its 1,188 rows reach ±100 and 612 reach ±50. One single metal row sits at ±150. So the two files are not two price points on one shelf. They are two shelves that barely overlap on the field that matters most.

We have not seen this counted anywhere. It is the whole reason a thick film shunt and a metal plate shunt are not interchangeable at the same resistance value, and it is invisible on any selector that lets you filter by resistance first.

Does the TCR grade get worse as the resistance falls?

Yes, and sharply. We grouped all 10,428 thick film rows into resistance bands and took the best TCR grade available in each. Above 0.050 Ω, 1,128 of 1,637 rows in the two middle bands reach ±100 ppm/°C. Between 0.010 Ω and 0.049 Ω, only 26 of 806 do — 3.2%. Below 0.010 Ω the thick film file holds exactly two parts, both at ±200 ppm/°C.

The metal shelf runs the other way: 559 of its 1,188 rows are below 0.010 Ω, and its lowest value is 0.0005 Ω. The thick film shelf is deepest exactly where a shunt is least useful, and thinnest where high-side current sensing actually lives.

What does one 0.010 Ω position look like across Walsin’s current sense series?

Seven real parts against one requirement — 0.010 Ω, ±1% tolerance, 2512 or smaller. We counted 32 thick film rows and 79 metal rows at exactly 0.010 Ω. At 2512 alone the TCR grades present run from ±50 to ±2,100 ppm/°C, a 42:1 spread on the same resistance in the same footprint. We will not tell you a part is interchangeable. We will show you where it differs.

Four of the seven match on resistance, tolerance and case size and still differ on the one field that sets your sense error at 85 °C. Confirm against both datasheets and qualify in your own circuit — that step stays with you, and we will not pretend otherwise.

Does the export tell you whether a part is four-terminal or Kelvin-sensed?

No. We read every column header in both files: Part Number, Series Group, Series, Size, Resistance, Tolerance, TCR, Rated Power, Packaging, Termination. There is no terminal-count column, no thermal resistance column, no parasitic inductance column and no derating curve. Ten fields, and three of the four things that decide whether a shunt measures correctly are absent.

What the export does give you is a footprint hint. The metal file carries three footprints that the thick film file does not — 1225(3263), 0612 and 0306 — across 74 rows, and the thick film file holds the catalogue’s rarest footprint of all, 0815, with exactly four part numbers. Wide-terminal and reverse geometries exist precisely because the terminal contribution matters at these resistances. The export will show you the case code; it will not tell you what the terminals are doing.

Why do 124 rows state TCR as 0 to 350 instead of ±350?

Because the Reverse series uses a one-sided notation that the rest of the file does not. We counted it: 124 of the 10,428 thick film rows state TCR as 0 ~ 250 or 0 ~ 350, and all 124 sit in Thick Film Power Low ohm Current Sense Chip Resistor ( Reverse ). The metal file has zero such rows. So the TCR column holds two incompatible formats and cannot be sorted or range-filtered numerically without being cleaned first.

This matters more than it sounds. All 26 of Walsin’s 0201 current sense parts are in that Reverse series, and every one of them states TCR as 0 ~ 350. If 0201 is your footprint, the only TCR figure Walsin publishes for you is in the notation no selector can read. A one-sided band is also a different engineering claim from a symmetric one — a part guaranteed to drift only upward is easier to compensate than one that may drift either way — and that distinction is thrown away the moment the column is parsed as a number.

What does the datasheet say, and do we hold it?

We do not hold it. We checked our own datasheet library: 28 Walsin PDFs, 451 pages, of which exactly two are chip resistor sheets — Walsin_MR_Automotive_Thick_Film_Chip_Resistor.pdf and Walsin_WR_General_Purpose_Chip_Resistor.pdf. Neither covers the WW current sense families in this post. For these part numbers we hold no datasheet at all, and the export is all we have.

That is the honest answer to “what the datasheet won’t tell you”: for Walsin’s current sense lines, we have not seen the datasheet. So every TCR figure above is quoted as the export states it, the derating curve and thermal resistance are not in our file, and the sheet is on our request list to Walsin rather than requested. We will tell you what we do not have. Most distributors will not.

Where we can check a figure, we do. UL file E182369 covers Walsin’s safety capacitor line and is searchable in UL’s own public database in about thirty seconds — that is the standard this post is held to, and it is the standard the current sense TCR figures currently fail.

What should a buyer in the United States or Germany do with this?

Decide the TCR grade before the resistance value, then cross the whole list in one pass. A 0.010 Ω position has 111 Walsin candidates across both files; filtering to ±50 ppm/°C cuts it to 35, all of them metal. The trade press reported MLCC and resistor lead times stretching through 2026 while AI server and EV build-outs drew on the same capacity, so the practical question is which of the candidates is actually in a warehouse.

1. Write the TCR grade into the requirement, not the review. If your sense amplifier budget assumes ±50 ppm/°C, Walsin’s thick film shelf is out at every resistance value, and knowing that before you cross saves a round of candidates.
2. Cross the whole BOM at once. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool. It is matched against Walsin’s published catalogue and returns candidates field by field, with every difference from your original stated rather than hidden. Filter by commercial or automotive grade, or for soft termination, high temperature, safety certified, high Q / low ESR or low profile.
3. Check what is physically in Hong Kong on ready stock before you commit to a production slot. That page is a dated snapshot as at 23 September 2026, not a live feed, and 254 of its 1,125 codes are chip resistors.

For the thick film and metal comparison at value level, see Low ohm current sense: thick film vs metal. For the precision end of the same catalogue, see High precision thick film vs thin film precision. The full range is on the Walsin chip resistor range page.

The short version

Current sense resistor TCR is the field that separates Walsin’s two low-ohm shelves, and the separation is absolute rather than gradual. Zero of 10,428 thick film rows reach ±50 ppm/°C; 612 of 1,188 metal rows do. Below 0.010 Ω the thick film file holds two parts and the metal file holds 559. At 2512 and 0.010 Ω the same resistance in the same footprint is offered at ±50 and at ±2,100 — a 42:1 spread. The export carries no terminal-count, thermal-resistance or inductance column, 124 rows state TCR in a notation that will not sort, and we hold no datasheet for either family. Qualification stays with you.

Send us the sense resistors off your BOM with the TCR grade your error budget actually needs, and we will come back with Walsin candidates field by field, differences included — then tell you which of them was in Hong Kong on 23 September 2026. If your 0201 shunt depends on a 0 ~ 350 TCR, tell us: that is the figure we most want Walsin to confirm, and your question is what gets it asked.

Frequently asked questions