Zero Ohm Jumper Rated Current From Watts: 34 of 34 Walsin WR and MR Rows Overshoot the Datasheet by 5 to 58 Percent

A zero ohm jumper sized from the export’s rated power overshoots the datasheet current on all 34 Walsin WR and MR rows we could check, by 5 to 58 percent. The sheets rate a jumper in amperes, and three MR 0805 rows rated 1/4 W and 1/8 W share one figure: 1.5 A.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the Walsin Technology (Walsin) chip resistor exports and two chip resistor approval sheets. This post is written from Thick_Film_General_Purpose_Jumper.xlsx, which holds 74 zero ohm rows, and from the jumper current tables in Walsin_WR_General_Purpose_Chip_Resistor.pdf and Walsin_MR_Automotive_Thick_Film_Chip_Resistor.pdf. Every part number below is real. The export gives a jumper a wattage and no current. We tested what happens if you derive one.

Can you size a zero ohm jumper’s current from the rated power in the export?

No, and the error runs the dangerous way. We opened the jumper file and computed the current each row’s rated power would allow at the sheets’ 50 milliohm resistance ceiling, the square root of power divided by resistance, then compared it with the rated current in the sheet for that size. It exceeds the sheet on 34 of 34 rows at sizes a sheet tabulates. The overshoot is 5 to 58 percent, and 10 rows overshoot by 41 percent or more.

Overshoot of sheet current	Rows	Case sizes and rated powers	Match / mismatch against the sheet current
5%	9	0805 at 1/8 W, 1210 at 1/2 W	Mismatch — small but one-directional
12%	15	1206 at 1/4 W, 0402 at 1/16 W	Mismatch
41%	8	0603 at 1/10 W, 0402 at 1/10 W	Mismatch
49%	1	0805 at 1/4 W (MR)	Mismatch
58%	1	0603 at 1/8 W (MR)	Mismatch
All	34	WR 20 rows, MR 14 rows	Mismatch on 34 of 34

We have not seen this counted anywhere. Earlier posts printed the sheet’s jumper currents. Zero ohm resistor current rating across seven jumper files counted which rows resolve to a sheet at all. Neither of those jumper posts ran the watts through I squared R. The result is that a figure in the Rated Power column of a jumper row says almost nothing about the amperes.

What does the arithmetic give at each case size?

At every size the sheet current is lower than the current the watts allow, and the gap varies by a factor of three. At rated current the 50 milliohm ceiling dissipates only 40 to 90 percent of the printed rating. We worked every size and rated power pair that the file holds against the sheet table. The WR table prints a maximum of 50 milliohm; the MR table prints 50 milliohm for the P tolerance.

Part number	Size	Export rated power	Sheet rated current	Current the watts allow at 50 milliohm	Overshoot	Share of rating used at sheet current	Your incumbent	Match / mismatch
MR10X000 PTL	1210	1/2 W	3 A	3.16 A	+5%	90%		Mismatch
MR12X000 PTL	1206	1/4 W	2 A	2.24 A	+12%	80%		Mismatch
WR12X000 PTL	1206	1/4 W	2 A	2.24 A	+12%	80%		Mismatch
WR08X000 PTL	0805	1/8 W	1.5 A	1.58 A	+5%	90%		Mismatch
MR08X000 PTL	0805	1/4 W	1.5 A	2.24 A	+49%	45%		Mismatch
WR06X000 PTL	0603	1/10 W	1 A	1.41 A	+41%	50%		Mismatch
MR06X000 PTL	0603	1/8 W	1 A	1.58 A	+58%	40%		Mismatch
WR04X000 PTL	0402	1/16 W	1 A	1.12 A	+12%	80%		Mismatch
MR04X000 PTL	0402	1/10 W	1 A	1.41 A	+41%	50%		Mismatch

The sheets’ peak currents are the same kind of figure. They run 2.0 times the rated current at 0402, 2.3 at 0805, 2.5 at 1206 and 1210, and 3.0 at 0603, with no pattern in the wattage. The 40 to 90 percent shares of the printed rating say the current limit is set by something other than the dissipation rule. The sheets do not say what.

Do two rated powers at one case size carry two currents?

No, and this is the plainest proof that watts do not set amperes. We lined up the MR jumper rows at the three sizes where the export holds two rated powers under the MR prefix. All nine rows share one sheet current per size. MR 0805 jumpers are rated 1/4 W on MR08X000 PTL and 1/8 W on MR08X000 PTLV and MR08X000 PTR, a 2 to 1 spread, and the sheet gives 1.5 A to all three.

Size	Rated powers in the MR rows	Spread	Sheet current	Rows	Match / mismatch of current across the powers
0805	1/4 W and 1/8 W	2.0 to 1	1.5 A	3	Match — one current
0603	1/8 W and 1/10 W	1.25 to 1	1 A	3	Match — one current
0402	1/10 W and 1/16 W	1.6 to 1	1 A	3	Match — one current

The WR 0805 jumper, WR08X000 PTL, is rated 1/8 W and also 1.5 A. So the WR 1/8 W part and the MR 1/4 W part carry the same current at the same size, a fact easy to miss when the Rated Power column shows a doubling. The reverse also holds: the export would let you rank the MR 0805 above the WR 0805, and the sheets would not.

Which jumper rows can be checked against a datasheet at all?

34 of 74. We matched every row of the jumper file to the case sizes the two sheets tabulate. The other 40 rows have a wattage and no current anywhere in the documents we hold. These counts are the ones we published earlier; the arithmetic above applies only to the first row of the table.

Prefix	Rows in the file	At a size the sheet tabulates	No current figure held	Match / mismatch
WR	47	20	27	Match on 20, mismatch on 27
MR	18	14	4	Match on 14, mismatch on 4
SR	9	0	9	Mismatch — no SR sheet held
Total	74	34	40

All 74 rows are the P tolerance, ending X000 P plus the reel letters. None carries the 0000 code for the F tolerance, and the MR sheet’s F jumper (up to 4 A at 1210) has no row in the 137 chip resistor files; the gap is covered in chip resistor jumpers and 0 ohm parts. Out of the 40 unchecked rows, 27 are WR at 0201, 01005, 1210, 1218, 2010 and 2512.

What should a jumper selection check before it is released?

Three things, and none of them is the Rated Power column. We read the Rated Power column across all 74 jumper rows and found it carries watts from 1/32 W to 1 W: it is the series figure copied down, not a jumper limit.

1. Take the current from the sheet, not the wattage. For WR and MR at the sizes tabulated, read rated and peak current by size from the approval sheet. We send the sheet for your part number on request.
2. Treat an unchecked row as unchecked. For 0201, 01005, 1210 on WR, 1218, 2010, 2512 and every SR row, we hold no current figure. Ask us rather than assuming.
3. Cross the whole list in one pass on the free cross-reference tool. Paste up to 500 part numbers or drop an Excel or CSV. It is matched against Walsin’s published catalogue and states every difference from your original. Then check ready stock, a dated snapshot of 1,125 part numbers as at 23 September 2026, not a live feed.

The case-size rating ladder is in chip resistor power rating by case size. The range sits on the Walsin chip resistor page. Confirm against both datasheets and qualify in your own circuit.

The short version

We computed the current each jumper’s wattage would allow at the sheets’ 50 milliohm ceiling and compared it with the sheet. It overshoots on 34 of 34 checkable rows, by 5 to 58 percent, and the share of the printed rating used at the sheet’s rated current runs from 40 to 90 percent. Three MR 0805 rows rated 1/4 W and 1/8 W share 1.5 A. 40 of 74 rows have no current figure in any sheet we hold. We will not tell you a jumper is a substitute for another because the watts match. We will show you the amperes the sheet prints. Qualification stays with you.

Send us the jumper lines off your BOM with the current you need to carry, and we will tell you which we can back with a sheet. And a question back: when you chose a 0 ohm link by its wattage, what current did you assume?

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Frequently asked questions

<!– wp:rank-math/faq-block {"questions":[{"id":"faq-question-01","title":"What is the rated current of a Walsin zero ohm jumper?","content":"It depends on case size and prefix. The WR and MR sheets print 2 A at 1206, 1.5 A at 0805, 1 A at 0603 and 1 A at 0402 for the P tolerance, and the MR sheet adds 3 A at 1210. Peak currents are 5 A, 3.5 A, 3 A, 2 A and 7.5 A respectively.","visible":true},{"id":"faq-question-02","title":"Can I work out jumper current from the Rated Power column?","content":"No. We tested all 34 rows at sizes a sheet tabulates: the current the watts allow at the 50 milliohm ceiling exceeds the sheet current on every row, by 5 to 58 percent. At rated current the part dissipates only 40 to 90 percent of the printed rating.","visible":true},{"id":"faq-question-03","title":"Why do three MR 0805 jumpers share one current?","content":"Because the sheet rates current by case size, not by wattage. MR08X000 PTL is rated 1/4 W and MR08X000 PTLV and MR08X000 PTR are rated 1/8 W, a 2 to 1 spread, and the MR sheet prints 1.5 A for the 0805 size. The same holds at 0603 and 0402.”,”visible”:true},{“id”:”faq-question-04″,”title”:”How many Walsin jumper rows have a documented current?”,”content”:”34 of 74 in the general purpose jumper file: 20 WR rows at 1206, 0805, 0603 and 0402, and 14 MR rows at five sizes. The other 40 rows, including all 9 SR rows, have a wattage and no current in any document we hold.”,”visible”:true},{“id”:”faq-question-05″,”title”:”Does the export include the F tolerance jumper?”,”content”:”No. All 74 rows in the general purpose jumper file are the P tolerance, ending X000 P plus reel letters. The MR sheet prints a higher current for the F tolerance, 4 A at 1210, but none of the 137 chip resistor export files carries a row with the 0000 code.”,”visible”:true},{“id”:”faq-question-06″,”title”:”Is the 50 milliohm figure the real resistance?”,”content”:”No. It is the ceiling printed on the sheets, so the real resistance is lower. We used it to show that rated power does not predict rated current, not to claim any jumper fails at its rated current. Confirm the basis of the current rating with Walsin.”,”visible”:true}],”listStyle”:””,”titleWrapper”:”h3″,”titleCssClasses”:””,”contentCssClasses”:””,”sizeSlug”:””} –>

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