Walsin Automotive Inductors: MCB, MHC and MCI Compared

Walsin Technology (Walsin) marks automotive inductors two different ways in the same
export. The 139-part MCI Automotive Series matches the 501-part commercial MCI Series
one field at a time, with identical Q Min, SRF and RDC on all 139 pairs and rated current
differing on only 5. The 150-part “MCB / MHC Automotive Series” bundles two different part
number prefixes under one series name instead. Read the series text, not the prefix, before
you assume a part is automotive-marked consistently.

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the full 5,410-row
Walsin inductor parametric export (5,411 rows as delivered, one of them a QA test row we
exclude from every count). This post is written from that export. Venatech holds no Walsin
inductor datasheet PDF, and 208 parts across the VEFL, WIP, SCM, SCA and BIH series have no
datasheet at all. Confirm every specification below against Walsin’s own documentation before design-in.
Every part number is real.

Which Walsin inductor series are marked automotive?

Two series names, out of 47 in the export, carry the word “Automotive.” MCI Automotive
Series holds 139 parts. MCB / MHC Automotive Series holds 150 parts. That is 289 of 5,410
inductor rows — 5.3% of the line — carrying an explicit automotive marker in the Series
field, the same way the chip resistor line marks automotive grade in free text rather than
a dedicated column.

Does the automotive marking work the same way on every prefix?

No. MCI keeps a clean one-to-one split — one automotive series name, one prefix, one
commercial counterpart series. MCB and MHC do not. Walsin files 82 MHC-prefixed parts and
68 MCB-prefixed parts under the single series name “MCB / MHC Automotive Series,” while the
commercial side keeps MCB and MHC apart across five separate series names (MCB-S, MCB-H,
MCB-B, MHC-S, MHC-P). A filter that expects one prefix per automotive series name will work
on MCI and silently merge two product lines on MCB/MHC.

One more thing the MCB/MHC family clarifies: the Inductance column reads 0.0 on every one
of its 150 automotive rows (and on its commercial counterparts), because these are ferrite
bead parts specified by impedance at 100 MHz, not by inductance. The real rating sits in
the Impedance (100MHz[Ω]) column. A query that sorts on Inductance will not distinguish
any of these 150 parts from each other.

What actually differs between an MCI Automotive part and its commercial MCI twin?

Almost nothing, electrically. Every one of the 139 MCI Automotive parts matches a
commercial MCI part on size, inductance and tolerance. Q Min, SRF(min) and RDC are
identical on all 139 matched pairs. Rated current matches on 134 of the 139 pairs and
differs on 5 — three at 1005(0402) where the automotive part is rated 100 mA lower
than its commercial twin, and two at 1608(0603) where the automotive part is rated 100 mA
higher.

The part number marker is a single character: Q for commercial, Z (1005 size) or H
(1608 size) for automotive, in the position right after the four-digit size code. Nothing
else in the part number signals automotive grade.

Can I get the smallest automotive inductor size Walsin sells commercially?

No. The commercial MCI Series covers three case sizes — 0603(0201), 1005(0402) and
1608(0603) — and 349 of its 501 parts, 69.7% of the series, are at the smallest size,
0603(0201). MCI Automotive Series covers only 1005(0402) and 1608(0603). If your commercial
BOM line is a 0603(0201) MCI inductor, there is no automotive-marked part at that footprint
in this series at all; the smallest automotive option is one case size larger.

Are these parts AEC-Q200 certified?

Walsin’s series naming says “Automotive.” We hold no Walsin inductor datasheet to check
the exact compliance wording against, unlike the MR and WR chip resistor lines where
Venatech holds both PDFs and the datasheets state “compliant,” not “certified.” For
inductors we cannot make even that distinction from what we hold. Request the AEC-Q200
qualification documentation for the specific part number before you design it in, and treat
“Automotive” in a Walsin series name as a sourcing signal, not a qualification claim, until
Walsin confirms it in writing for that part.

For the general construction trade-offs across Walsin’s inductor families, see
Multilayer vs wirewound chip inductors. For
why rated current alone is the wrong figure to design to, see
Rated current vs saturation current in chip inductors.
The full inductor range is on the Walsin inductor page.

The short version

MCI’s automotive marking is clean: one prefix, one series name, a near-exact electrical
match to its commercial twin except for 5 of 139 parts’ rated current. MCB/MHC’s automotive
marking is not: one series name covers two prefixes that stay separate on the commercial
side. Neither family lets you source the smallest commercial case size in automotive grade.

Send us the MCI, MCB or MHC part number from your BOM and we will tell you whether an
automotive-marked part at the same footprint exists, and what differs if it does.

Check it against the catalogue yourself. Cross-reference accepts one part number or a whole BOM column and prints the mismatches as plainly as the matches — qualification stays with you, which is the honest division of labour. Ready stock covers the inductor lines held in Hong Kong.

Frequently asked questions