For EV charger current sensing in the USA, Walsin Technology (Walsin) lists 172 part numbers in 2512 at 5 milliohms or less. Only 24 of them carry a 50 ppm temperature coefficient, and every one of those sits at 3, 4 or 5 milliohms. Below 3 milliohms the best published figure is 70 ppm.
Venatech Limited, an authorised Walsin distributor in Hong Kong, wrote this for a design or sourcing engineer at a US maker of EV chargers or charger power modules who needs a low-ohm shunt. It is built from the Walsin chip resistor export, which we re-measured on 10 November 2026: 234,815 rows and 234,401 distinct part numbers. Every part number below is real, and every count is ours.
What did the US charging network look like in June 2026, and why does it matter for a sense resistor?
It was large and still growing at the fast end. EV Infrastructure News reported on 17 June 2026, citing the US Department of Energy’s Alternative Fuels Data Center, that US public charging passed 250,000 ports: 250,406 ports at 80,543 locations, of which 73,951 were DC fast ports as at 1 June 2026.
We cannot say what any charger maker buys. The engineering consequence is plain, though: each charger port has at least one current measurement for metering and protection, and DC fast units add module-level sensing. The question for the shunt is how much current it can carry at what accuracy over temperature. Source: EV Infrastructure News, 17 June 2026, fetched 10 November 2026 (link under Sources).
How many 2512 current sense resistors does Walsin list at 5 milliohms or less?
There are 172 of them. We parsed every current sense and power sensing series in the Walsin export (11,616 part numbers across 10 series) and found 172 in 2512 at 5 milliohms or less, spread over seven values from 0.5 to 5 milliohms.
All 172 are metal plate or metal foil. The two thick film parts at 5 milliohms or less sit in other case sizes. Across all sizes the figure is 319 part numbers at 5 milliohms or less. The 2512 count dominates because that is where the power rating lives: 1 W, 2 W or 3 W, against 0.5 W or less in the small sizes.
| Resistance | 2512 parts | Rated power published | TCR published |
|---|---|---|---|
| 0.5 milliohm | 4 | 3 W | 70 ppm |
| 0.75 milliohm | 4 | 3 W | 70 ppm |
| 1 milliohm | 28 | 1 W to 3 W | 70, 75 or 100 ppm |
| 2 milliohm | 34 | 1 W to 3 W | 70, 75 or 100 ppm |
| 3 milliohm | 34 | 1 W to 3 W | 50, 70, 75 or 100 ppm |
| 4 milliohm | 34 | 1 W to 3 W | 50, 70, 75 or 100 ppm |
| 5 milliohm | 34 | 1 W to 3 W | 50, 70, 75 or 100 ppm |
Which 2512 parts reach 50 ppm, and at what resistance?
Only the 3, 4 and 5 milliohm values. We counted TCR by value: 24 of the 172 reach 50 ppm (8 each at 3, 4 and 5 milliohms); the 28 parts at 1 milliohm carry 70 ppm on 24, 75 on 2 and 100 on 2; the 8 parts at 0.5 and 0.75 milliohm are all 70 ppm.
We have not seen this counted anywhere. A designer who wants a 1 milliohm shunt at 50 ppm will not find it in this export, and should either relax the TCR or accept a different value with more amplifier gain. The table crosses one worked brief: 2512, 3 milliohms, plus or minus 1 percent, 50 ppm, and at least 25 A implied by the power rating.
| Walsin part | Description | On shelf 23 Sep 2026 | Match / mismatch with the brief | Your incumbent |
|---|---|---|---|---|
WW25NR003FTL |
Metal plate power, 2512, 3 milliohm, plus or minus 1 percent, 50 ppm, 2 W | No | Match on every field; implies 25.8 A | |
WW25MR003FTL |
Same family, 3 milliohm, plus or minus 1 percent, 50 ppm, 1 W | No | Match on size, value, tolerance, TCR; mismatch: 1 W implies 18.3 A | |
WW25NR003JTL |
Same, plus or minus 5 percent | No | Mismatch: tolerance is five times wider | |
WW25NR005FTL |
5 milliohm, plus or minus 1 percent, 50 ppm, 2 W | No | Mismatch: value is 5 milliohms; implies 20.0 A | |
WW25BR001FTL |
Metal plate, 1 milliohm, plus or minus 1 percent, 70 ppm, 3 W | No | Mismatch: value and TCR differ; implies 54.8 A | |
WW25QR002FTL |
Metal plate power, 2 milliohm, plus or minus 1 percent, 100 ppm, 1 W | No | Mismatch: value, TCR and power |
A match here is a match on export fields, nothing more. Our post on low-ohm current sense, thick film against metal explains the family split, and chip resistor power rating by case size covers the derating question.
How much current does a 2512 sense resistor imply at each rated power?
Between 14 A and 77 A across this range. Taking the square root of rated power over resistance, the 2512 parts at 5 milliohms imply 14.1 A at 1 W and 20.0 A at 2 W, and the 0.5 milliohm 3 W parts imply 77.5 A; we checked the arithmetic on all 172 rows.
This is a ceiling from the power rating alone. It is not a datasheet current rating, and it ignores land pattern, copper, ambient temperature and the derating curve. The Walsin chip resistor datasheets we hold are the general-purpose and automotive sheets, so we cannot cite a current rating for these series. Request the datasheet for your exact part number and size the copper yourself.
What is on the Hong Kong shelf for charger current sensing?
Nothing at 5 milliohms or less. Of the 11,616 current sense part numbers we parsed, 3 are on our stock list dated 23 September 2026, all in the thick film low-ohm series at 0805 and between 0.27 and 0.47 ohm, so none of the 319 parts at 5 milliohms or less is stocked.
The stock list holds 1,125 distinct codes, 254 of them chip resistors, and 183 chip resistor part numbers matched to the export. It is a dated snapshot, not live, and the Walsin chip resistor range lists the families. For a milliohm shunt the route is a to-order enquiry through the site, and we make no promise on timing.
What do we hold on Stackpole current sense resistors?
Nothing parametric, and we will not guess. Stackpole is a line Venatech supplies; Walsin is the only line we are authorised for. When we tried to read stackpole.com on 10 November 2026, every page we requested redirected to the johnsonelectric.com homepage, which carried no product data, so this post cites no Stackpole specification.
We hold no Stackpole export and no Stackpole datasheet. If you design around a Stackpole current sense part, send us the part number and its datasheet and we will read it against the Walsin fields in the table above, saying which differ. We state no Stackpole availability or lifecycle position. Confirm against both datasheets and qualify in your own circuit.
How can Venatech help a US charger designer?
How Venatech helps starts with a free paste box. The cross-reference tool (VenaMatch) decodes 18 manufacturers’ part numbers across 800,000+ crossable parts, accepts up to 500 part numbers or an Excel or CSV file, and marks each field match or mismatch. Load a charger BOM to check every resistor line in one pass. The ready-stock list is a Hong Kong snapshot dated 23 September 2026.
We serve from Hong Kong in small lots, and you request a quote through the site. Walsin is our authorised line; Stackpole and Viking are lines we supply. We give no legal, customs or compliance advice, so confirm with your compliance team. Qualification stays with you.
The short version
For a US EV charger shunt, Walsin lists 172 parts in 2512 at 5 milliohms or less, 24 of them at 50 ppm and only at 3 to 5 milliohms. The shelf holds none of them. Name the value, the TCR and the power, not just the size.
Send us one shunt line from your charger BOM with the resistance, tolerance, TCR and current you can accept, and we will return the Walsin parts with every difference stated. If your incumbent is a 1 milliohm part at 50 ppm, which field are you willing to move?
Related reading
- Low-ohm current sense: thick film against metal
- Anti-surge chip resistors
- Chip resistor power rating by case size
- Free cross-reference tool and the dated ready-stock list
Last reviewed 10 Nov 2026.
Sources
Fetched 10 November 2026.
- EV Infrastructure News, US public EV charging network surpasses 250,000 charging ports, 17 June 2026: https://www.evinfrastructurenews.com/ev-networks/us-public-ev-charging-network-surpasses-250-000-charging-ports
- Venatech Walsin chip resistor export, re-measured 10 November 2026; Venatech stock list, as at 23 September 2026.
Frequently asked questions
How many public EV charging ports did the USA have in June 2026?
EV Infrastructure News reported on 17 June 2026, citing the US Department of Energy’s Alternative Fuels Data Center, 250,406 public ports at 80,543 locations, including 73,951 DC fast ports as at 1 June 2026. We did not verify the count independently.
What is the lowest resistance Walsin lists in a 2512 current sense resistor?
0.5 milliohm, on 4 part numbers, all metal plate at 3 W and 70 ppm. The export lists seven 2512 values from 0.5 to 5 milliohms across 172 part numbers. Confirm each against its datasheet.
Does Walsin offer a 1 milliohm 2512 resistor at 50 ppm?
Not in the export we parsed. The 28 parts at 1 milliohm in 2512 carry 70 ppm on 24, 75 ppm on 2 and 100 ppm on 2. The 50 ppm parts begin at 3 milliohms.
Is WW25NR003FTL a drop-in match for a 3 milliohm, 1 percent, 50 ppm, 2512 shunt?
It matches those export fields and implies 25.8 A from its 2 W rating. That is not a datasheet current rating. Check layout, derating and the datasheet, and qualify in your own circuit.
Does Venatech hold Stackpole current sense data?
No. Stackpole is a line we supply and Walsin is the only line we are authorised for. We hold no Stackpole export or datasheet, and stackpole.com redirected to the johnsonelectric.com homepage when we tried it on 10 November 2026.
Are any milliohm Walsin shunts on the Hong Kong shelf?
Not at 5 milliohms or less. As at 23 September 2026 only 3 current sense part numbers are stocked, all 0805 between 0.27 and 0.47 ohm. The snapshot is dated, not live, so ask through the site.