Walsin Inductor Series: How to Tell Them Apart

Walsin Technology (Walsin) publishes 47 distinct inductor series across 5,410 real part
numbers in the extract Venatech holds. 21 of those 47 series — nearly half — hold fewer
than 20 parts each. Six series (WLCW, WCI, WCA, WQCW, WLCM, MCI) account for 3,762 of the
5,410 parts, so most of the catalogue sits in a handful of large families and the rest is a
long tail of narrow, size-specific or application-specific lines.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin’s full inductor
parametric export — 5,411 rows, one of which (Test123999) is a QA test row with the free
text “TEST Saturation current 123.88” in a numeric column and is excluded from every count
below. The real total is 5,410 parts. Every part number in this post is real and checked
against that extract.

How many inductor series does Walsin actually publish?

47, after excluding the QA test row. Here are all of them, largest first, with part count
and the case sizes each one covers:

Which inductor series are effectively long-tail?

21 of the 47 series hold fewer than 20 parts each — from WLPH(HC) and WIP_S at 19 down to
WIP_Y Series at 4. Between them those 21 series total 246 parts, 4.5% of the catalogue, spread
across sizes as small as 1005(0402) and as large as 7265 (7.2 × 6.5 mm).

A short line is not a defect. Several of these are single-size, single-application families —
WLPN is 5 parts at one 2.0 × 2.0 mm footprint, MCB-B Series is 4 parts at 1005(0402) only.
But a series with 4–8 part numbers gives you almost no room to retarget inductance or
tolerance if your first choice goes out of stock, and it is worth knowing that before you
design one in. If your BOM carries a part from MIP-H Series, MCB-B Series or WIP_Y
Series, ask us for the full family list before committing — there may be only three or four
alternatives in the entire Walsin range.

Does Inductance always mean the same thing across series?

No. The Inductance column carries three different units across the catalogue — nH on 4,125
rows, µH on 644 rows and Ω on 641 rows — and the unit depends on the series, not on a
separate flag you can filter on. The Ω rows are not inductance at all: they are ferrite bead
series (WLBD, WLBD(HC), MCB-S, MHC-S, MCB/MHC Automotive and others) reporting an impedance
figure in the same column a wirewound inductor uses for nH.

Two series go further and mix units within themselves. WIP_A Series carries six rows in
µH and two in nH, all at the same 3225 case size — a plain numeric sort on Inductance puts a
0.47 µH part and a 1.5 nH part, three orders of magnitude apart, next to each other with
nothing to tell them apart but the Unit cell. WQBD Series carries four rows in nH and 41
in Ω, because it mixes true inductor rows with bead rows in one series name.

What does one electrical point look like across four different series?

Here are four real 0805 parts, all at 100 nH, all with identical DC resistance, rated current
and Q min. The only things that change are series name, tolerance code and, on one series, how
self-resonant frequency is expressed.

The WLCW row is not a typo we can confirm or deny. We cross-checked the same inductance and
case size in the sibling
multilayer vs wirewound inductors comparison
and found the same pattern: WLCW’s SRF(min) figure runs 1,000× lower than WCA, WCI and WQCW
at this exact size. One plausible read is that WLCW states SRF in GHz at 2012(0805) while the
other three state it in MHz, but we hold nothing in writing from Walsin that confirms it.

Which series has no datasheet on file at Venatech?

None of the 47 — we hold zero Walsin inductor datasheet PDFs for any series, which is why
every specification claim in this post is flagged above. Five series are worse off again:
VEFL, WIP, SCM, SCA and BIH have no datasheet published anywhere that Venatech has located,
208 parts in total. If a part from one of those five sits on your BOM, treat the parametric
row as the only information available and ask Walsin directly for qualification data before
you commit.

The short version

47 series, 5,410 real parts, and the six largest series carry 70% of the catalogue between
them. Filtering by size code alone is not enough — the Inductance column’s unit changes by
series, two series mix units internally, and SRF is not comparable across series without
checking units first. None of the 47 series has a datasheet PDF on file with Venatech.

Send us your inductor BOM and we will tell you which series each part sits in, what the
real alternatives are if the series is a long-tail one, and which specification figures need
confirming with Walsin before you qualify. Browse the full
Walsin inductor range or ask us to cross a part.

Already holding a part number? Paste it into the cross-reference tool — it reads the manufacturer from the number itself, returns the Walsin inductor candidates and states every field that differs rather than calling anything an alternative. Then check Hong Kong ready stock to see what is on the shelf today.

Frequently asked questions