Selecting apower-line common-mode chokeis not a matter of sorting impedance values from low to high. Within the VOOHUWHACM15A60R series, five options share a 15.0 ± 0.5 × 13.0 ± 0.5 × 6.6 mm outline and an 80 V maximum rated voltage. Their reference impedance at 100 MHz/0.1 V, however, spans 300 to 1500 Ω, while maximum rated current ranges from 13 A down to 5 A and maximum DCR rises from 5 to 23 mΩ. Those differences make current capability, winding resistance, and impedance a combined decision.
For a board already constrained to the 1513-size outline, compare the WHACM15A60R301, 501, 701, 102, and 152 directly. Remove options that do not meet the current or DCR target before impedance curves and board tests decide the final part.
1. Start with three parameters that cannot replace one another
The 100 MHz impedance value is one test point
Each part lists minimum and reference impedance at 100 MHz with a 0.1 V test signal. That gives a consistent first comparison inside the series, but it does not describe performance at every other frequency. If the troublesome common-mode energy sits elsewhere, review the impedance-versus-frequency curve or run an A/B board test under the same conditions. A 1500 Ω value at 100 MHz must not be treated as proof that the part is better than a 300 Ω option across the entire spectrum.
Rated current determines which options remain viable
Maximum continuous current, load-step or startup peaks, and the actual enclosure temperature all matter. The 301 option is rated at 13 A, the 501 and 701 at 10 A, the 102 at 9 A, and the 152 at 5 A. If the rail is already close to 10 A, the 152 should not lead the shortlist simply because it has the highest reference impedance.
DCR points to voltage drop and copper-loss trade-offs
DCR is the winding's DC resistance. At the same current, a lower DCR generally helps reduce DC voltage drop and winding loss. Across these five series specifications, higher reference impedance is paired with higher DCR and a lower current rating. That is an observation about this series, not a substitute for a thermal test; copper area, nearby heat sources, airflow, and ambient temperature still shape the result.
2. Comparing the five WHACM15A60R options
The table uses a single measurement context. Z Min and Z Ref are specified at 100 MHz/0.1 V; DCR and rated current are shown as specified maximum values. All five options also list an 80 V maximum rated voltage and a 10 MΩ minimum insulation resistance.
| VOOHU part | Z Min | Z Ref | DCR Max | Current Max | Useful first screen |
|---|---|---|---|---|---|
| WHACM15A60R301 | 225 Ω | 300 Ω | 5 mΩ | 13 A | Highest current rating and the lowest DCR in this five-part group |
| WHACM15A60R501 | 400 Ω | 500 Ω | 6 mΩ | 10 A | Lower-DCR starting point when 10 A and the 500 Ω class fit the design |
| WHACM15A60R701 | 500 Ω | 700 Ω | 7 mΩ | 10 A | Also rated 10 A; useful for an A/B check against the 501 option |
| WHACM15A60R102 | 800 Ω | 1000 Ω | 10 mΩ | 9 A | Candidate when higher single-point impedance is needed and 9 A is sufficient |
| WHACM15A60R152 | 1200 Ω | 1500 Ω | 23 mΩ | 5 A | Highest single-point impedance, paired with the lowest current rating and highest DCR |
The 501 and 701 make a particularly clean comparison: both are rated at 10 A and share the same outline and voltage rating. The 501 lists 500 Ω Ref. and 6 mΩ Max, while the 701 lists 700 Ω Ref. and 7 mΩ Max. If both satisfy the mechanical and electrical limits, test them on the same board at the same load. Then compare the target-frequency noise, input drop, and surface temperature before deciding whether the extra 100 MHz impedance is worth the 1 mΩ DCR difference.
3. Build the shortlist from the load current
Higher-current inputs: start with the 301, 501, and 701
A 12 V, 24 V, or 48 V label does not choose the part by itself; start with the highest continuous current through the choke. Above 10 A, only theWHACM15A60R301reaches a 13 A rating in this group. When 10 A covers the design boundary, the 501 and 701 provide two impedance grades for an A/B check. Startup, load transients, and worst-case ambient temperature should remain part of sample validation.
Moderate-current inputs: do not compare the 102 and 152 by impedance alone
When 9 A is sufficient, theWHACM15A60R102combines a 1000 Ω reference value with 10 mΩ maximum DCR. TheWHACM15A60R152raises the reference value to 1500 Ω, but its rating falls to 5 A and DCR rises to 23 mΩ. The 152 becomes a reasonable candidate only when the 5 A boundary is adequate and measurements at the problem frequency support the higher-impedance grade.
4. Checks to complete before placing a same-size option on the board
- Use maximum continuous current, short peaks, and worst-case ambient temperature to remove parts with insufficient current rating.
- Keep the 100 MHz point separate from the actual noise spectrum; obtain impedance curves or samples when the target band is elsewhere.
- Check the current drawing for pinout, land pattern, height, tolerances, and orientation. A shared outline does not remove the need for a drawing review.
- On the same PCB, record input drop, surface temperature, and conducted spectrum with the same cable, load, and instrument setup.
- Do not treat the 80 V rated-voltage field as a dielectric-withstand rating. Confirm insulation and safety requirements separately.
Once DC-port conducted-emissions testing begins, follow VOOHU's focused guide topower-line chokes in DC-port conducted-emissions work. For BOM screening and sample planning, use the table above to narrow the options first.
5. FAQ: selecting a WHACM15A60R power-line common-mode choke
Q1. Is a higher common-mode impedance always better?
No. The WHACM15A60R values are single-point measurements at 100 MHz/0.1 V. The part must also meet current, DCR, voltage, and target-frequency requirements. A higher impedance number does not compensate for an inadequate current rating.
Q2. How should the common-mode choke current rating be selected?
Start with maximum continuous current and expected peaks, then account for worst-case ambient temperature, PCB cooling, and permitted temperature rise. The rating is a device limit, not the preferred normal operating point; verify drop, temperature, and function under the intended load.
Q3. How should DCR be compared?
At the same current and with a comparable structure, lower DCR generally helps reduce DC drop and copper loss. The five maximum values are 5, 6, 7, 10, and 23 mΩ from the 301 through the 152. DCR still has to be balanced against impedance at the frequency of interest.
Q4. Can the 300, 500, 700, 1000, and 1500 Ω values be used directly?
Use them for first screening only. They are reference values at 100 MHz/0.1 V. Review the impedance curve and confirm the change in the target noise band on the actual board.
Q5. Are the five same-size parts automatically interchangeable?
No. The common 15.0 × 13.0 × 6.6 mm outline is only one mechanical attribute. Check the current drawing for pinout, pads, tolerances, and orientation, then repeat current, thermal, and EMI validation after a change.
Q6. Is the 80 V rating the same as dielectric withstand voltage?
No. Rated operating voltage and dielectric withstand are different specifications. If the design has insulation or safety requirements, confirm withstand voltage, insulation resistance, creepage, and the applicable standard separately.
6. Conclusion: narrow the range with current and DCR, then let measurements decide
The five WHACM15A60R options place 300–1500 Ω reference impedance, 5–13 A current ratings, and 5–23 mΩ maximum DCR in the same outline. For higher-current rails, begin with the 301, 501, and 701. The 102 and 152 become candidates only after the load boundary allows them. Then close the decision with the full impedance curve and board-level voltage-drop, temperature, and spectrum results. VOOHU can help arrange a focused sample set based on operating voltage, current range, target frequency band, and available board space.
