Common mode impedance
The impedance the CMC presents to common mode noise at a stated test frequency. Compare candidates only at the same frequency, then read the full curve across your failing band.
Inductor products
Signal Line Common Mode Chokes
On a differential pair the choke has to suppress common mode noise without damaging the signal itself. Start from the interface and the frequency band your scan fails, then check that the impedance peak sits away from your signal's fundamental and that insertion loss stays acceptable.
Part number search & selector
Find Signal Line Common Mode Chokes part numbers
The table uses the current English-site product records, published selection fields and part-specific technical-file links.
* Frozen Image and Part Number columns · drag horizontally to review all specifications
| Image | Datasheet | Compare | Downloads |
Size
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Common Mode Impedance ΩMin
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Common Mode Impedance (Ωtyp)
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Inductance (uH) +50/–30%
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RDC (Ω)Max
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Leakage Inductance (nH) typ
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Isolation Resistance (MΩ) Min
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Rated Current Max
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Rated Voltage (V) Max
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| Image | Part number | Datasheet | Compare | Downloads | Size | Common Mode Impedance ΩMin | Common Mode Impedance (Ωtyp) | Inductance (uH) +50/–30% | RDC (Ω)Max | Leakage Inductance (nH) typ | Isolation Resistance (MΩ) Min | Rated Current Max | Rated Voltage (V) Max | Sample |
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WHAC-3225B-201U4 | SPEC | 3225 | - | - | 200 | 4 | - | 10 | 70mA | 80 |
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WHAC-3225B-800U3 | SPEC | 3225 | - | - | 80 | 2.5 | - | 10 | 150mA | 80 |
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WHAC-3225B-101U0 | SPEC | 3225 | 2200 | 5100 | 100 | 4.9 | 180 | 10 | 150mA | 80 |
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WHAC3225B510U0 | SPEC | 3225 | 1000 | 2600 | 51 | 1.6 | 130 | 10 | 200mA | 80 |
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WHAC-3225B-220U0 | SPEC | 3225 | 500 | 1100 | 22 | 1 | 70 | 10 | 250mA | 80 |
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WHAC-3225B-110U0 | SPEC | 3225 | 300 | 550 | 11 | 0.8 | 50 | 10 | 300mA | 80 |
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By interface
Chokes by interface: USB, CAN, Ethernet, HDMI
The interface sets the data rate and therefore what the choke is allowed to do to the signal.
How to select
Signal line common mode choke selection in four steps
Interface and data rate come first, then the failing band, then the effect on the signal, then the footprint between the traces.
- 01
Name the interface and its rate
USB 2.0, CAN FD, 100BASE-T1, HDMI and LVDS each run at a different rate with a different signalling scheme. The rate sets how much loss and imbalance the signal line common mode choke may add.
- 02
Find the failing band
Read where the radiated or conducted scan crosses the limit. You need common mode impedance that is high across that band and low differential loss where the signal itself has energy.
- 03
Protect the differential pair
Check the differential insertion loss curve or cutoff frequency in the datasheet, keep DCR low on pairs that also carry bias current, and keep the trace geometry symmetric through the part.
- 04
Verify on the real link
Measure the eye diagram, return loss and emissions on your own board. Datasheet curves come from a reference fixture, and the layout around the choke changes both signal integrity and EMI.
Parameters
Signal line common mode choke ratings explained
Read each value together with its test condition. Impedance in particular only means something next to the frequency at which it was measured.
Differential mode loss and cutoff frequency
How much of the wanted signal the part removes. Some datasheets give a cutoff frequency for the differential path; keep it well above the signal's fundamental and confirm by measurement.
DC resistance (DCR)
Adds series loss on the pair and a voltage drop where the pair also carries current. Read the maximum figure rather than a typical one when the pair powers a remote node.
Rated current
Only binding when the pair carries bias or power as well as data. On a pure data pair, a signal line choke is chosen on impedance placement and signal integrity long before current matters.
Package size
The 2012, 3225 and 4532 size codes set board area and how the differential traces enter and leave the part. Smaller packages ease routing but usually offer less impedance.
Mode conversion
Asymmetry between the two windings converts common mode noise into differential noise on the signal. It is why a choke can worsen an eye diagram, and it shows up only in measurement.
Compare
SMD common mode choke series by package size
The WH2012, WHAC2012A and WHLC2012A series share the 2012 footprint, while WHAC3225B and WHAC4532A move up in body size. Within one size, impedance level separates the parts; the interface decides which level fits.
Return to the selector ↑| Size | Parts | Common Mode Impedance ΩMin | Common Mode Impedance (Ωtyp) | Inductance (uH) +50/–30% | RDC (Ω)Max | Leakage Inductance (nH) typ | Isolation Resistance (MΩ) Min | Rated Current Max | Rated Voltage (V) Max | Action |
|---|---|---|---|---|---|---|---|---|---|---|
| 2012 | 13 | - | 120, 1200, 1000, 800, 380, 360, 260, 180, 90, 75 | - | 0.3, 0.35, 0.4, 0.45, 0.55, 0.88, 1.3, 1.5 | - | 10 | 280mA, 300mA, 400mA | 50, 125 | Filter → |
| 3225 | 6 | 300, 500, 1000, 2200, - | 550, 1100, 2600, 5100, - | 11, 22, 51, 80, 100, 200 | 0.8, 1, 1.6, 2.5, 4, 4.9 | 50, 70, 130, 180, - | 10 | 70mA, 150mA, 200mA, 250mA, 300mA | 80 | Filter → |
| 4532 | 15 | 300, 500, 1000, 2000, - | 600, 1200, 2800, 5800, 90±25%, 420±25%, 600±25%, 800±25%, 1000±25%, 1400±25%, 1400 | 11, 22, 51, 100, - | 0.25, 1.2, 1.4, 1.8, 2.5, 0.039, 0.06, 0.082, 0.089, 0.113, 0.148 | 50, 80, 150, 200, - | 10 | 150mA, 200mA, 250mA, 700mA, 1.0A, 1.5A, 1.8A, 2.0A, 2.2A, 3.0A | 50 | Filter → |
Application review
Signal line common mode choke applications by interface
For each interface, confirm the data rate, whether the pair also carries bias current and what the operating environment demands before the part is fixed.
USB common mode choke for data lines
- Confirm the USB generation: USB 2.0 high-speed runs at 480 Mbit/s
- Keep the impedance peak away from the signal's fundamental
- Check the eye diagram against the USB template after fitting the choke
CAN bus common mode choke for vehicle and industrial networks
- Check the bus common mode voltage range and any bias current on the pair
- CAN FD data phases run faster than classic CAN, so recheck the signal margin
- For in-vehicle use, confirm AEC-Q200 status of the exact part number with VOOHU
Common mode choke for Ethernet ports
- Confirm the link speed and how the choke works with the LAN transformer already on the port
- Automotive single-pair links usually set tighter mode conversion limits
- Measure link stability and emissions together, not one at a time
Common mode choke for HDMI and LVDS links
- An HDMI common mode choke sees high data rates, which make differential loss and mode conversion critical
- Place the choke close to the connector and keep the pair symmetric through it
- Measure the eye before and after instead of relying on the datasheet curve
Documents
Common mode choke datasheet, 3D model and PCB footprint files
Each signal line part number links its datasheet with the impedance curve and land pattern, and most also carry a 3D model and a PCB footprint for direct import into your CAD library.
Showing representative available file sets. Search to find a specific SKU.
WHLC-2012A-121T12012
WHLC-2012A-381T02012
WHLC-2012A-900T02012
WHLC-2012A-181T02012
WHLC-2012A-261T02012
WHLC-2012A-361T12012
- 35
- PDF datasheets listed
- 35
- 3D file sets listed
- 28
- PCB footprints listed
VOOHU’s published product content is reviewed by its engineering team. Specifications, downloads and technical support information are tied to specific part numbers, so you can verify them before requesting samples or a quotation.
Category overview
Choosing a common mode choke for a differential pair
On a supply rail a choke only has to pass current. On a differential pair it has to pass a waveform intact, so a chip common mode choke is chosen by interface, impedance placement and winding symmetry rather than by current.
Why the interface comes first
A part that is comfortable on a CAN bus can wreck a USB link, because the data rates differ by orders of magnitude. Classic CAN runs at up to 1 Mbit/s and CAN FD data phases run several times faster, while USB 2.0 high-speed signalling runs at 480 Mbit/s and display links such as HDMI run faster again per lane. The interface sets how much differential loss and how much impedance in the signal path the link can tolerate.
So decide the interface and its rate before comparing impedance figures. An LVDS common mode choke for a display cable, for example, is judged mainly on differential loss and symmetry, while a part on a slow fieldbus pair can afford far more impedance.
Where the impedance peak sits
You want high common mode impedance across the band that fails your scan and low differential loss at the frequencies the signal itself occupies. If the impedance peak sits close to the signal's fundamental, imbalance in the part lets it attenuate the wanted signal along with the noise. Read the datasheet curves, mark both frequencies, and check that they are well apart.
Compare impedance only at a stated test frequency. Chip parts for data lines are conventionally specified at 100 MHz, but confirm the frequency printed in each datasheet before ranking candidates, because a figure without its frequency cannot be compared with another.
Mode conversion is the hidden risk
Real parts are never perfectly symmetric. Any imbalance between the two windings converts common mode noise into differential noise, which lands directly on the signal, and the effect grows with data rate. This is why a choke sometimes makes an eye diagram worse, and why the result cannot be fully predicted from the datasheet: measure the eye and return loss on your own board.
Mode conversion is also why automotive Ethernet links such as 100BASE-T1 set tight limits on any choke in the path, and why a gigabit Ethernet common mode choke is usually chosen together with the LAN transformer on the port rather than on its own. For an automotive Ethernet common mode choke, look for mode conversion data in the datasheet and confirm qualification with VOOHU before design-in.
FAQ
Signal line common mode choke questions by interface
Answers cover interface fit, eye diagram impact, the LAN transformer question, package size codes and qualification.
Why does the interface matter more than the package?
The interface sets the data rate, and the data rate decides how much the choke may affect the signal. A part that is fine on a CAN bus running at hundreds of kilobits can badly degrade a USB or HDMI link running orders of magnitude faster. When you pick a common mode choke for CAN bus, USB or display use, start from the interface, then filter on impedance and size.
Is a signal line common mode choke the same as a common mode filter?
For a single component, in practice yes. Many catalogues list chip parts for data lines as a common mode filter. Inductor-centred catalogues call the same part a common mode inductor, and some use data line choke. On a supply rail the word filter often means a whole network of choke and capacitors; on a signal pair it usually means this one part. Compare impedance curves, differential loss and DCR rather than the name.
Can a common mode choke make the eye diagram worse?
Yes, and it is a common surprise. No real part is perfectly symmetric, and any imbalance between the windings converts common mode noise into differential noise that lands on the signal. The effect grows with data rate, so the only reliable check is measuring the eye before and after on your own hardware.
Do I need an Ethernet common mode choke if the port already has a LAN transformer?
Sometimes. A LAN transformer provides isolation and some common mode rejection, and many LAN magnetics already include a choke. On higher speed links or in difficult enclosures that may not be enough. Whether an extra part helps depends on your layout and scan result, so measure rather than assume.
What do the 2012, 3225 and 4532 size codes mean?
They are metric codes for the body outline. A 2012 common mode choke is about 2.0 by 1.2 mm, the footprint inch-based catalogues call an 0805 common mode choke. A 3225 common mode choke is about 3.2 by 2.5 mm, and a 4532 common mode choke about 4.5 by 3.2 mm. Check the outline drawing in the datasheet, because land patterns can differ between series with the same size code.
Are parts in the same package size interchangeable?
No. Package size tells you the footprint, not the electrical behaviour. Two parts of identical size can have very different impedance curves, DCR and symmetry. Compare the impedance at your frequency, the DC resistance and the recommended land pattern, and verify on your board before treating one as a substitute for another.
Are these parts AEC-Q200 qualified?
The selector table does not state AEC-Q200 qualification, so do not assume it from a series name. If the part is going into a vehicle network such as CAN FD or automotive Ethernet, ask VOOHU to confirm the qualification status of the exact part number before design-in.
How do I request signal line common mode choke samples or a quote?
VOOHU manufactures these chokes and makes its magnetics in its own factory in Mianyang. With a complete part number, send the part number, quantity and the date you need it. If you are still selecting, send the interface and data rate, the band where your scan fails and the space between the traces. Samples are available for evaluation, and selected parts are free of charge. Our FAE team will be glad to confirm the options for your project.
Engineer support
Continue after product selection
Send the candidate part number and the condition you need reviewed. Sample support can be added after the selection is clear; commercial questions may be discussed in the same engineering conversation.
- 1Selected part numbers
- 2Engineering review
- 3Sample request
- 4Commercial discussion
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