Push-pull transformer selection comparison: VOOHU WH41-111 and Würth Elektronik 78931812505 replacement evaluation
Push-pull transformer selection comparison: VOOHU WH41-111 and Würth Elektronik 78931812505 replacement evaluation
1. Competitor Product Overview (Würth Elektronik)
For a center-tapped push-pull supply or isolated-interface design, Würth Elektronik 78931812505 is a 1208, six-pin WE-PSPA push-pull transformer. Its two winding groups use terminals 1-2-3 and 6-5-4. In a cross-reference evaluation, turns ratio, volt-second capability, insulation-test conditions and PCB land pattern should be checked together.
2. VOOHU Replacement Overview (Suzhou VOOHU Electronic Technology Co., Ltd.)
VOOHU WH41-111 is a six-pin push-pull transformer using the same two center-tapped terminal groups, 1-2-3 and 6-5-4, with a 1:1.1 turns ratio. Its maximum length is 12.6 mm and maximum height is 4.1 mm, placing it in the same screening set for this type of push-pull design. Before adoption, verify left/right terminal positions, land dimensions, core operating margin and insulation-test duration.
3. Key Parameter Comparison
This table keeps only parameters that map to the same terminal function on both parts. Similar values do not prove a direct replacement; items with different test conditions or recommended lands must be checked under the original design conditions.
| Parameter | Würth Elektronik 78931812505 | VOOHU WH41-111 |
|---|---|---|
| Terminal layout / winding topology | 6 pins; two center-tapped winding groups: 1-2-3 and 6-5-4 | 6 pins; two center-tapped winding groups: 1-2-3 and 6-5-4 |
| Turns ratio n, (1-3):(6-4) | 1:1.13, ±2% | 1:1.1 |
| Insulation test voltage | 2500 V(AC), 1 mA / 1 s | 2.5 kV(AC), 1 mA / 60 s |
| Volt-second capability, ∫Udt | 9.5 Vµs (N(1-2)) | 8.6 Vµs (N1, bipolar waveform) |
| Leakage inductance | ≤600 nH (100 kHz / 100 mV) | ≤1.0 µH (100 kHz / 0.01 V) |
| Maximum body length | 12.6 mm max. | 12.6 mm max. |
| Maximum height | 4.1 mm max. | 4.1 mm max. |
| Tape-and-reel quantity | 900 pcs / reel | 800 pcs / reel |
Notes:
- The 1-2-3 / 6-5-4 functional positions match, but the recommended land patterns are not identical. Check pad geometry, terminal landing points, stencil apertures and assembly clearance; six pins plus matching length and height are not proof of P2P interchangeability.
- Both parts show a 2.5 kV AC insulation test, but the applied duration differs. Confirm the hipot criterion, lot-sampling plan and system safety requirement during sample validation.
- DC-resistance definitions differ: Würth Elektronik lists (1-2), (2-3), (6-5) and (5-4) separately, while WH41-111 lists the total 1-3 and 6-4 windings. The values are not suitable for a direct numerical comparison.
4. Applications
- Push-pull DC/DC supplies using a six-pin center-tapped transformer, with schematic polarity and rectifier or driver connections checked first.
- Gate-drive isolation supplies and low-voltage isolated power stages using bidirectional core magnetization, with frequency, duty cycle and volt-second margin calculated before sampling.
- Existing-board sourcing changes or new-project introduction after PCB-overlay review, sample reflow and full-load temperature-rise verification.
5. FAQ
Q1: Can WH41-111 directly replace 78931812505?
No direct conclusion should be drawn from pin count, outline and a similar turns ratio. Recommended lands, leakage-inductance test conditions, volt-second sampling conditions and insulation-test duration differ, so PCB review and sample-on-board validation are required.
Q2: Why is turns ratio alone not enough for a push-pull transformer?
Turns ratio is only part of the voltage-transfer relationship. Volt-second capability, switching frequency, duty cycle, leakage inductance, winding polarity and rectification all affect core margin, switching spikes and output behavior.
Q3: How should leakage inductance be checked?
Match frequency, test voltage, shorting method and measurement terminals before comparing values. The two entries here use different test voltages, so 600 nH and 1.0 µH should not be treated as a direct performance ranking.
Q4: When should the insulation test be repeated?
Repeat system-level verification whenever the transformer, PCB spacing, potting material or safety class changes, using the actual test duration, current and pass/fail criterion for the end product.
Why VOOHU?
One-stop sourcing:connectors + magnetics + interface chips, full support from selection to small-batch production.
Custom solutions:just share your application requirements and budget to get a tailored solution with professional technical support.
Fast development:direct from the manufacturer, rapid FAE response, efficient sampling, shorter time-to-market.
Core qualifications:ISO9001, ISO14001, RoHS, REACH; two in-house factories ensure delivery and quality.
For more information, visit VOOHU:China www.voohu.cn | Overseas www.voohuele.com| Technical support: song.lei@voohu.cn
Replacement Cross-Reference
Manufacturer: Würth Elektronik | Part number: 78931812505 | Key comparison points: six-pin center-tapped topology, 1:1.13 turns ratio, 2.5 kV AC insulation test and 9.5 Vµs. VOOHU WH41-111 is a candidate for replacement evaluation; validate the PCB and samples before release.
