Common mode impedance
The resistance the choke presents to common mode noise, quoted at a stated frequency. Compare candidates at the same frequency or the values do not correspond.
Inductor products
Power Line Common Mode Chokes
A common mode choke blocks noise that travels the same direction on both conductors while letting the supply current pass. Start from the frequency band your measurement actually fails, pick the impedance that covers it, then check rated current and DC resistance against the load the line has to carry.
Part number search & selector
Find Power 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 |
Dimensions(L*W*H MAX)
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Z(Ω) 100MHz/0.1V Min.
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Z(Ω) 100MHz/0.1V Ref.
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DC Resistance (mΩ) Max.
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Rated DC Current (A)Max.
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Insulation Resistance (MΩ)Min.
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Rated Voltage (V)Max.
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| Image | Part number | Datasheet | Compare | Downloads | Dimensions(L*W*H MAX) | Z(Ω) 100MHz/0.1V Min. | Z(Ω) 100MHz/0.1V Ref. | DC Resistance (mΩ) Max. | Rated DC Current (A)Max. | Insulation Resistance (MΩ)Min. | Rated Voltage (V)Max. | Sample |
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WHACM09A50R302 | SPEC | 9070 | 2500 | 3000 | 75 | 3 | 10 | 50 |
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WHACM09A50R222 | SPEC | 9070 | 1700 | 2200 | 60 | 2.5 | 10 | 50 |
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WHACM09A50R102 | SPEC | 9070 | 750 | 1000 | 13 | 4 | 10 | 50 |
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WHACM09A50R701 | SPEC | 9070 | 500 | 700 | 10 | 5 | 10 | 50 |
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WHACM09A50R601 | SPEC | 9070 | 450 | 600 | 8 | 5.5 | 10 | 50 |
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WHACM09A50R301 | SPEC | 9070 | 225 | 300 | 6 | 6 | 10 | 50 |
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No matching part numbers
Broaden the selected filters or clear the current search.
By series
Power line common mode choke families
Families differ in construction and size band, which sets impedance and current together.
01WHAL1211A Series7 part numbers
02WHPL1211A SERIES7 part numbers
03WHAL1513A Series5 part numbers
04WHAL4520A Series14 part numbers
05WHAL7060A Series9 part numbers
06WHAL9070A Series6 part numbers
07WHACM07A40R Series9 part numbers
08WHACM09A50R Series6 part numbers
09WHACM12A65R Series7 part numbers
10WHACM15A60R Series5 part numbers
How to select
Selecting a power line common mode choke in four steps
Work from the failing frequency band outward to current, losses and board space.
- 01
Identify the failing band
Read the frequency range where your conducted emission scan exceeds the limit. That band, not a general noise complaint, decides which impedance curve you need.
- 02
Match the impedance curve
Pick a part whose common mode impedance peaks across the failing band. Read the impedance at that frequency, not the headline figure at the family's peak.
- 03
Check current and DC resistance
The rated current must cover the worst-case load with margin. DC resistance sets the voltage drop and the heat the winding has to shed.
- 04
Confirm the mechanical fit
Check size, land pattern and clearance to neighbouring parts, then re-scan on your own board because layout changes the result.
Parameters
Reading common mode choke ratings
Impedance is a curve, not a single number, so read the test frequency with the value.
Rated current
The continuous current the winding carries under stated temperature-rise conditions. Derate for ambient temperature and restricted airflow inside the enclosure.
DC resistance
Winding resistance, usually a maximum figure. It sets the conduction loss and the voltage drop the supply has to tolerate at full load.
Common mode inductance
Measured with both windings in the common mode configuration. Higher inductance generally moves the impedance peak toward lower frequencies.
Leakage inductance
The part of the winding that does not couple. It acts on differential signals and can be useful, but it also limits how high a current the part handles.
Withstand voltage
Isolation between the two windings under a stated test. Select against the safety requirement that applies to the equipment, not the working voltage.
Compare
Common mode choke families side by side
Size band drives impedance and current capability more than family naming does.
Return to the selector ↑| Dimensions(L*W*H MAX) | Parts | Z(Ω) 100MHz/0.1V Min. | Z(Ω) 100MHz/0.1V Ref. | DC Resistance (mΩ) Max. | Rated DC Current (A)Max. | Insulation Resistance (MΩ)Min. | Rated Voltage (V)Max. | Action |
|---|---|---|---|---|---|---|---|---|
| 1211 | 7 | 80, 500, 600, 750, 2200, 2300 | 230, 700, 800, 1000, 2500, 2700 | 2, 4, 6, 8, 14, 35, 50 | 1.5, 1.8, 6, 8, 10 | 10 | 125 | Filter → |
| 1513 | 5 | 225, 400, 500, 800, 1200 | 300, 500, 700, 1000, 1500 | 5, 6, 7, 10, 23 | 5, 9, 10, 13 | 10 | 80 | Filter → |
| 4520 | 14 | 60, 90, 180, 200, 250, 300, 350, 500, 650, 800, 1000, 1200, 1800, 2500 | 90, 150, 230, 300, 380, 420, 500, 700, 900, 1000, 1200, 1400, 2000, 3000 | 35, 40, 45, 50, 55, 58, 60, 70, 80 | 1, 1.5, 1.9, 2.0, 2.1, 2.2, 2.4, 2.5, 3, 3.2 | 10 | 50 | Filter → |
| 7060 | 9 | 40, 100, 225, 275, 500, 800, 910, 2000, 2500 | 70, 140, 300, 450, 700, 1020, 1300, 2700, 3000 | 5, 10, 15, 17, 21, 63, 75 | 0.9, 1, 2.5, 3, 4, 5, 9, 15 | 10 | 125 | Filter → |
| 9070 | 6 | 225, 450, 500, 750, 1700, 2500 | 300, 600, 700, 1000, 2200, 3000 | 6, 8, 10, 13, 60, 75 | 2.5, 3, 4, 5, 5.5, 6 | 10 | 50 | Filter → |
Application review
Where power line common mode chokes are fitted
Confirm the line current, the failing band and how much board space the filter can take.
AC mains input filtering
- Confirm the line current and the failing band from the conducted scan, then verify the withstand voltage meets the equipment safety case.
DC power distribution
- Check the rated current against the worst-case load and confirm DC resistance does not push the rail below tolerance at full draw.
Motor drives and inverters
- Switching noise is broadband. Verify the impedance curve covers the whole failing range, not just the fundamental switching frequency.
Industrial power supplies
- Space and temperature rise usually decide. Confirm the derated current at the real ambient inside the enclosure.
Documents
Common mode choke datasheets and drawings
Datasheets carry the impedance curve, current rating and recommended land pattern.
Showing representative available file sets. Search to find a specific SKU.
- 41
- PDF datasheets listed
- 1
- 3D file sets listed
- 0
- 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
How a common mode choke works and how to choose one
Most selection mistakes here come from treating impedance as a single number, or from confusing common mode with differential mode noise.
Discuss a new design
Contact FAE for a replacement assessment.
Already have a part number? Request samples or a quote.
Common mode versus differential mode
Differential noise travels out on one conductor and back on the other. Common mode noise travels the same direction on both and returns through ground. A choke winds both conductors on one core so their supply currents cancel, while common mode current sees a high impedance. That is why it filters one and passes the other.
Impedance is a curve
The headline impedance figure is measured at one frequency. What matters is whether the curve is high across the band where your conducted emission scan actually fails. A part with a higher peak in the wrong place will not help. Read the curve from the datasheet, identify your failing band first, and match the two.
What limits the choice
Rated current and DC resistance set the ceiling. A choke with excellent impedance is useless if the winding cannot carry the load current, or if its resistance drops the rail below tolerance. Check those against worst case, then confirm on your own board, because layout and the rest of the filter change the measured result.
FAQ
Common mode choke questions engineers ask
Answers cover how the choke works, how to read impedance and where it belongs.
What does a common mode choke actually do?
It winds both conductors of a line on one shared core. Supply current flows out on one and back on the other, so the two magnetic fields cancel and the choke is almost invisible to it. Common mode noise flows the same direction on both conductors, its fields add, and the choke presents a high impedance that blocks it.
What is the difference between common mode and differential mode noise?
Differential noise travels out on one conductor and back on the other, between the two lines. Common mode noise travels the same direction on both and returns through ground or chassis. A common mode choke is built to block the second kind while passing the first, which is why it filters supply lines without dropping the supply.
How do I read the impedance figure?
Impedance is a curve across frequency, and the headline number is measured at one stated point. Start from the frequency band where your conducted emission scan fails, then read each candidate's impedance at that frequency. A part with a higher peak somewhere else will not fix your specific failure.
Is a common mode choke the same as a common mode filter?
In everyday use the terms overlap, but a filter usually means the whole network, including Y capacitors and sometimes a differential inductor, while the choke is one component in it. When you specify a part, specify the choke. When you design the stage, think about the whole filter and how its parts interact.
Why does rated current matter so much?
The winding has to carry the full supply current continuously. Exceeding the rated current drives temperature rise beyond what the part was qualified for, and in ferrite parts it can push the core toward saturation, at which point the impedance collapses and the filtering stops working. Derate for the real ambient temperature.
Should I choose a toroidal or an SMD part?
Toroidal parts generally offer higher impedance and current capability for a given cost, at the price of board area and height. SMD parts suit automated assembly and tighter boards. Start from the impedance and current you need, then let the mechanical constraints decide which construction fits.
Why does the choke work on the bench but not in the product?
Because the measured result depends on the whole loop, not just the component. Layout, the position of the filter relative to the noise source, the ground return path and the rest of the filter network all change what the scan sees. Always confirm on the real board in the real enclosure.
How do I request common mode choke samples or a quote?
With a complete part number, send the part number, quantity, delivery region and the date you need it. If you are still selecting, send the line voltage and current, the frequency band where your scan fails and the space available on the board, and a sales engineer will shortlist candidates.
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
For a replacement review
- Original part and datasheet
Include the document revision
- Operating conditions
Temperature, isolation voltage and PoE current basis
- Package constraints
Pin count, pitch and spacing between pin rows
- Project stage and annual volume
To help prioritize samples and evaluation
- Target review date
When you need candidates and a comparison of differences
Engineering review identifies candidate parts and explains the differences.
For samples and a quotation
- Candidate part numbers
From the selector or engineering review
- Quantity and project stage
Prototyping / pilot build / production
- Required delivery date
Specify sample and production timing separately
- Required documentation
Compliance documents, material declarations or third-party reports
Sample quantity, lead time and cost depend on the project stage and part number. Sales will respond on business days.
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