Chip Inductor Cross Reference: Only 146 of Walsin’s 5,410 Parts Publish a Saturation Current

We parsed all 5,410 rows of Walsin’s chip inductor export. Exactly 146 publish a saturation current. A chip inductor cross reference for any switching regulator turns on Isat, and 44 of the 47 series do not state one. Inductance, tolerance, footprint and DCR transfer cleanly. Saturation current does not transfer at all.

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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 one of those files, Walsin_Inductor_ALL.xlsx, and every part number below is real and came out of that file. Every count is a count of part numbers, not pieces. We hold no inductor datasheet at all — not one of the 28 PDFs covers an inductor family — so the export is the whole of our evidence, and we say so before you read a single figure.

How many of Walsin’s 5,410 chip inductors publish a saturation current?

One hundred and forty-six. We counted the filled cells in the Saturation Current column across the whole file: 146 of 5,410 rows, or 2.70%. Every other field a cross needs is populated on all 5,410 rows. The one field that decides whether your buck converter stays in continuous conduction at peak load is populated on one row in thirty-seven.

Field in Walsin_Inductor_ALL.xlsx	Rows populated	Share	Transfers to a cross?
Inductance and unit	5,410	100%	Yes
Tolerance	5,410	100%	Yes
Size and thickness	5,410	100%	Yes, with a caveat below
DCR (RDC)	5,410	100%	Yes, after the unit is read off the value
Rated current	5,410	100%	Yes, after the unit is read off the value
SRF (minimum)	4,413 non-zero	81.6%	Partly — 997 rows carry zero
Q (minimum)	4,328 non-zero	80.0%	Partly — 1,082 rows carry zero
Saturation current	146	2.70%	No
Operating temperature range	0	0%	No column exists
Core material or construction	0	0%	No column exists
AEC-Q200 status	0	0%	No column — inferable from 2 series names only

Fourteen columns, and three of the things a power-supply engineer must have are not among them. We have not seen this counted anywhere. It is the single reason an honest inductor cross is shorter than an honest MLCC cross: we can match the geometry and the DC resistance on every part in the catalogue, and we can match the saturation behaviour on 146 of them.

Which three series publish Isat, and what do they actually cover?

Three of 47. We grouped the 146 rows by series and every one falls into CSME, CSMEA or MIP-H — and within those three, the column is complete rather than patchy.

Series	Rows with Isat	Rows in series	Case sizes	Inductance range
CSME	89	89	4040, 5050, 6060	0.24 – 220 uH
CSMEA	53	53	4040, 5050, 6060	1.0 – 220 uH
MIP-H	4	4	1608 (0603), 2012 (0805)	2.2 – 4.7 uH
All other 44 series	0	5,264	—	—

Read that geometry carefully, because it is the whole commercial point. CSME and CSMEA are 4 mm square and larger. MIP-H is the only series publishing Isat below 4 mm, and it holds exactly four part numbers across two footprints and two inductance values. So if your rail needs a saturation-current figure and your footprint is 0603, 0805, 1008 or 1206, Walsin publishes one for you on four part numbers in the entire catalogue: MIP1608H2R2MBP, MIP1608H4R7MBP, MIP2012H2R2MBE and MIP2012H4R7MBE.

That is not a reason to walk away. It is the reason to ask us for the series datasheet rather than accept a cross built on a blank cell.

What does one 2.2 uH position look like across Walsin’s inductor series?

Fifty-six candidates, six of which publish the field you need. We filtered the export to 2.2 uH and counted 56 rows across 20 series. Rated current across those 56 runs from 365 mA to 15 A — a 41:1 spread at one inductance value. We will not tell you a part is interchangeable. We will show you where it differs.

Part number	Series	Size	Tolerance	DCR as printed	Rated current	Isat	Match / mismatch vs 2.2 uH, 0603, 1 A
MIP1608H2R2MBP	MIP-H	1608 (0603)	±20%	0.20 Ω	600 mA	230 mA	Match on L and footprint; mismatch — 600 mA rating is under 1 A, and Isat is 230 mA
MIP1608P2R2MBP	MIP-P	1608 (0603)	±20%	0.3 Ω	750 mA	—	Match on L and footprint; mismatch — no Isat published, higher DCR
MAP1608ST2R2MMPK	MAP	1608 (0603)	±20%	0.237 Ω	1.3 A	—	Match on L, footprint and current; mismatch — no Isat published
WLFI1608Z0M2R2TB	WLFI	1608 (0603)	±20%	1.15 Ω	15 A	—	Match on L and footprint; mismatch — 1.15 Ω DCR against a 15 A claim, flagged below
MIP2012H2R2MBE	MIP-H	2012 (0805)	±20%	0.17 Ω	900 mA	550 mA	Mismatch — 0805 footprint; the smallest Walsin part at this value with a real Isat
WIP201610S-2R2ML	WIP_S	2016	±20%	117 mΩ	2.2 A	—	Mismatch — larger footprint, but 19× lower DCR and double the current
CSMM0420D-2R2M	CSME	4040	±20%	0.056 Ω	4 A	6 A	Mismatch — 4 mm square; the smallest part here with Isat above rated current

Four of the seven match on inductance and footprint and differ on the field that decides whether the inductor collapses at peak current. Confirm against the Walsin datasheet and qualify in your own circuit — that step stays with you, and we are not going to pretend a populated geometry column substitutes for it.

Does the export tell you whether a row is an inductor or a ferrite bead?

Only if you read the Unit column, which most tools do not. We checked all 5,410 rows: the unit is nH on 4,126, uH on 644, and Ω on 641. Those 641 rows are not inductors with an inductance — they are ferrite beads whose headline figure is an impedance, and they sit in 19 of the 47 series, including both automotive series.

Two consequences follow, and both bite a cross.

First, a numeric sort on the Inductance column silently mixes three quantities. A row reading 600 is 600 nH, 600 uH or 600 Ω depending on a separate column, and the ratio between the first and second is a thousand to one. Second, the 641 Ω-unit rows are exactly the rows where Q is meaningless: of the 1,082 rows carrying Q = 0, 641 are the bead rows and 439 are uH-unit power inductors, which is a coherent pattern rather than missing data once you know what you are looking at. The Impedance (100MHz) column mirrors it — 609 of the 610 non-zero cells are Ω-unit rows.

The Size column has a smaller version of the same problem. Forty distinct strings, of which 25 rows in two series (WQQC and WLPN) state a raw millimetre pair such as 1.295*1.829 where every other row states a case code. A find-and-match on case code drops those 25 rows without telling you.

Why does a naive parse of this export produce an 0603 dissipating 35 kW?

Because the unit is glued to the value, and on some rows it is missing entirely. We multiplied rated current squared by DCR on every row — the cheapest sanity check in passive component work, and one nobody appears to run on a vendor export. Before any cleaning, 305 of 5,410 rows imply more than 1 W inside a chip and 244 imply more than 100 W.

Two unit conventions explain most of it, and we established both by inspection rather than assumption:

• Rated current carries no unit on 71 rows, all in WLCM, WLBD and WLBD(HC). A cell reading 9000 is 9,000 mA, not 9,000 A. Read as amps it produces 810 kW in a 1812 bead.
• DCR is printed in Ω where it must be mΩ on part of the CSME family. CSME0418D-2R2M states 42 Ω at a 2.2 A rating, which is 203 W. CSMM0420D-2R2M, in the same series file, states 0.056 Ω. The two conventions sit in one series.

Correct both and the impossible population falls from 305 rows to 106 rows above 1 W and 47 above 10 W, concentrated in four series: AIP, WLFI, VEFL and WQCW. The worst survivor is WQCW1608Z0GR47PB — 80 A through 5.5 Ω in an 0603, an implied 35.2 kW. That one is not a unit convention we have been able to find.

What is Test123999 doing in a production export?

We found it while counting, and it is worth a paragraph because it changes a number. One row of the 5,411 in the file is a test record: part number Test123999, series WLCW, impedance 11111, and a Saturation Current cell reading the literal string TEST Saturation current 123.88. It is the only WLCW row with anything in the Isat column.

So the honest catalogue count is 5,410 part numbers, not 5,411, and the honest series count for Isat is three, not four. Anyone measuring the same file without reading the cells will report 147 saturation currents across four series. We have not seen this flagged anywhere, and we are flagging it rather than quietly dropping the row, because a test record in a shipped production export tells you something real about how much validation a parametric file has had — which is exactly the judgement you need before you build a BOM on one.

That cuts both ways and we will say so: it is also a reminder that our own counts come from the same file, and that every figure in this post is an export value awaiting a datasheet.

What should a buyer in the United Kingdom do with this?

Decide whether your rail is saturation-limited before you cross, because the answer changes which 2.7% of the catalogue you are allowed to look at. A filter choke, a bead, an EMI inductor or an RF matching element is rated-current-limited and the whole 5,410-row shelf is open to you. A buck or boost inductor is saturation-limited, and Walsin publishes the figure on 146 parts, of which four are below 4 mm square. The trade press reported passive component lead times stretching through 2026 as AI server and EV build-outs drew on the same ferrite capacity, so the practical question is which candidate is in a warehouse rather than which is theoretically closest.

1. Write down which limit applies, in one line, before you cross anything. If it is Isat, say so in your enquiry and we will route you straight to CSME, CSMEA or MIP-H and tell you honestly if your footprint is not there.
2. Cross the whole BOM in one pass. Paste up to 500 part numbers or drop your Excel or CSV into the free cross-reference tool. It decodes 18 manufacturers’ part numbers and matches against 800,000+ crossable Walsin part numbers, returning candidates field by field with every difference from your original stated rather than hidden.
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.
4. Ask us for the inductor datasheet. We hold 28 Walsin datasheets, 451 pages, and none of them is an inductor sheet. Your request is what puts it on the list to Walsin, and we will tell you when it arrives rather than paraphrasing a figure we cannot see.

Check us while you are here. UL file E182369 is searchable in UL’s own public database in about thirty seconds, and TUV certificates R50381780 and R50195920 are named and numbered for the same reason.

For the inductor selection method, see Choosing an inductor for a buck converter. For what happens when a column looks like a selector and is not, see Four columns that look like selectors and select nothing. The full range is on the Walsin inductor range page.

The short version

A chip inductor cross reference is cheap on geometry and expensive on current. All 5,410 rows of Walsin’s inductor export publish inductance, tolerance, size, thickness, DCR and rated current. Exactly 146 publish a saturation current, in 3 of 47 series, and only 4 of those are below 4 mm square. One 2.2 uH requirement returns 56 candidates and 6 usable Isat figures. The unit lives inside the value rather than in a column, which is why a naive parse implies 35 kW in an 0603, and one row of the file is a test record called Test123999. We hold no inductor datasheet for any series, and we would rather tell you that than quote you a mechanism.

Send us the inductors off your BOM with one line saying whether each rail is saturation-limited or rated-current-limited, and we will come back with Walsin candidates field by field, blanks included — then tell you which of them was in Hong Kong on 23 September 2026. And if you think the 80 A at 5.5 Ω row has an explanation we have missed, tell us: that is the question we most want to put to Walsin, and your enquiry is what gets it asked.

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Frequently asked questions

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