At a single point — 10 nH in a 1608(0603) case — the published DC resistance (RDC) from
Walsin Technology (Walsin) ranges from 0.048 Ω to 0.30 Ω across 15 real part numbers in eight
series, a 6.25x spread for the identical nominal inductance and case size. Rated current and Q min move
with it: the lowest-RDC part is rated 1.4 A with Q min 49; the highest-RDC part is rated
600 mA with Q min 12. Inductance tells you the part fits the circuit electrically. RDC tells
you whether it survives the current.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin’s full inductor
parametric export of 5,410 real parts (one QA test row, Test123999, is excluded from every
count here). Every part number below is real and checked against that extract.
What is RDC and why does it matter more than inductance alone?
RDC is the inductor’s DC winding or trace resistance, in ohms. It sets the I²R loss at your
load current and, through self-heating, the practical current limit of the part — which is
usually what the Rated Current column actually measures. Two parts can share the same
inductance, tolerance and case size and still differ by more than 6x in RDC, which means they
differ by more than 6x in how much heat they generate at the same current.
How much can RDC vary at one inductance and one case size?
Here are all 15 real Walsin parts at exactly 10 nH in a 1608(0603) case, sorted by RDC:
| Part number | Series | RDC | Rated current | Q min | Match / mismatch |
|---|---|---|---|---|---|
| WLCW1608HQG10NPB | WLCW Series | 0.048 Ω | 1.4 A | 49 | reference: lowest RDC in the set |
| WLCW1608HQJ10NPB | WLCW Series | 0.048 Ω | 1.4 A | 49 | Match on RDC, current, Q min; mismatch is tolerance only |
| WLCW1608Z0G10NPB | WLCW Series | 0.13 Ω | 700 mA | 31 | Mismatch: 2.7x the reference RDC, half the rated current |
| WQCW1608Z0G10NPB | WQCW Series | 0.13 Ω | 700 mA | 31 | Mismatch: same as above, different series |
| WCI1608CP10NG | WCI Series | 0.13 Ω | 700 mA | 31 | Mismatch: same electrical point, different series |
| WCA1608CP10NG | WCA Series | 0.13 Ω | 700 mA | 31 | Mismatch: same electrical point, different series |
| WQCM1608A0J10NTB | WQCM Series | 0.30 Ω | 600 mA | 12 | Mismatch: 6.25x the reference RDC, Q min less than a quarter |
| WLCM1608Z2J10NTB | WLCM Series | 0.30 Ω | 600 mA | 12 | Mismatch: same as above |
| MCI1608HQ10NJHBP | MCI Series | 0.30 Ω | 600 mA | 12 | Mismatch: same as above |
| MCI1608HH10NJHBP | MCI Automotive Series | 0.30 Ω | 600 mA | 12 | Mismatch: same as above, automotive grade |
Four more part numbers duplicate these same RDC/current/Q combinations at a different
tolerance code and are omitted from the table for length, but are real and in the same
extract. The pattern holds: RDC runs 0.048 Ω to 0.30 Ω, a 6.25x spread, at one inductance and
one case size, and Q min and rated current fall in step with rising RDC.
Does RDC track rated current and Q min together?
Yes, consistently in this data set. As RDC rises from 0.048 Ω to 0.13 Ω to 0.30 Ω, rated
current falls from 1.4 A to 700 mA to 600 mA, and Q min falls from 49 to 31 to 12. All three
figures move together because they share a cause: more winding or trace resistance means more
self-heating per amp and more resistive loss at the test frequency, which is exactly what Q
penalises.
The practical consequence: a BOM line that quotes only inductance and tolerance, leaving RDC
and current unstated, is not actually specified. The same inductance value comes with a 6x
range of real-world consequences at this single data point alone.
Can a numeric match on inductance alone pick the wrong part?
Yes, and the clearest proof is a part that technically matches the number 10.0 but not the
inductance. WLFI1608Z0M100TB carries an Inductance value of 10.0 in the same 1608(0603)
case — but its Unit field reads µH, not nH. It is a 10,000 nH part, not a 10 nH part, three
orders of magnitude away from every part in the table above, and it carries RDC of 2.55 Ω and
a rated current of 15 A to match its much larger size of winding.
| Part number | Inductance (as published) | Unit | Actual inductance | RDC | Match / mismatch |
|---|---|---|---|---|---|
| WLCW1608HQG10NPB | 10.0 | nH | 10 nH | 0.048 Ω | reference: true 10 nH part |
| WLFI1608Z0M100TB | 10.0 | µH | 10,000 nH | 2.55 Ω | Mismatch: same numeral, 1,000x the real inductance and 53x the RDC |
A spreadsheet filter on Inductance == 10.0 with no check of the Unit column pulls both
rows into the same result set. Only the unit column tells you they are not the same part.
How should I actually shortlist by RDC?
Fix case size and inductance first, then sort the remaining candidates by RDC before you look
at anything else, because RDC is the field that predicts both current headroom and Q. If your
design needs more than 700 mA at 10 nH in a 1608(0603) footprint, only WLCW1608HQG10NPB and
its sibling tolerance code clear that bar in this data set — every other part at this exact
point tops out at 700 mA or less.
For the current-rating question this feeds into, see
rated current vs saturation current in chip inductors.
The full range is on the Walsin inductor range page.
The short version
At one inductance and one case size, RDC alone can separate real parts by more than 6x, and
rated current and Q min move with it in the same direction. A numeric filter on inductance that
ignores the Unit column can silently mix in a part three orders of magnitude off. Shortlist by
case size and inductance, then sort by RDC before anything else.
Send us your inductance, case size and current requirement and we will return the real part
numbers that clear it, sorted by RDC, not just by the number in the inductance column.
Faster than an email. The cross-reference tool takes a pasted list or a spreadsheet and returns Walsin inductor candidates field by field, differences included. Ready stock shows what is physically in Hong Kong, so you can see straight away whether a line is a stock pull or a production slot.
Frequently asked questions
What does RDC mean on an inductor datasheet or parametric table?
RDC is the DC winding or conductor resistance, measured in ohms. It drives I²R loss at your load current and is usually the real limit behind the published rated current, since more RDC means more self-heating at the same current.
How much can RDC vary between inductors with the same inductance and case size?
In Walsin’s data, at 10 nH in a 1608(0603) case, RDC spans 0.048 Ω to 0.30 Ω across 15 real part numbers in eight series — a 6.25x spread for the identical nominal inductance and footprint.
Does a lower RDC always mean a higher rated current?
In this data set, yes, consistently. As RDC rises from 0.048 Ω to 0.13 Ω to 0.30 Ω across the 10 nH / 1608(0603) group, rated current falls from 1.4 A to 700 mA to 600 mA, and Q min falls in step from 49 to 31 to 12.
Can two inductors with the same printed inductance value actually be very different parts?
Yes. WLFI1608Z0M100TB publishes an Inductance value of 10.0, identical to several true 10 nH parts in the same case size, but its Unit field reads µH — it is actually a 10,000 nH part with 2.55 Ω of RDC and a 15 A rating. A numeric-only match misses this.
Why would two parts have identical RDC, current and Q min but different series names?
Because several Walsin wirewound and multilayer series publish overlapping electrical specifications at the same case size and inductance. In the 10 nH / 1608(0603) group, WQCW, WCI and WCA all publish 0.13 Ω, 700 mA and Q min 31 — identical numbers under three different series names.
Should I pick an inductor by inductance first or RDC first?
Fix inductance and case size first, since those set the circuit fit, then sort the remaining candidates by RDC. RDC predicts current headroom and Q together, so it is the more decisive filter once inductance and footprint are fixed.