05.1
Samples
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LAN Transformer
WHD40103G 10/100BASE-TX LAN Transformer
Quad-port 10/100BASE-TX LAN transformer (Ethernet transformer): 40-pin DIP, 1500 Vrms isolation, not PoE rated. Operating temperature 0 to +70 °C.
- Data rate
- 10/100BASE-TX
- Ports
- Quad port
- Mounting
- DIP
- Isolation voltage
- 1500 Vrms
- PoE
- Not PoE rated
- Operating temperature
- 0 to +70 °C
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01Specifications
WHD40103G specifications
Key attributes
ParameterValue
Data rate
10/100BASE-TX
Ports
Quad port
Operating temperature
0 to +70 °C
PoE
Not PoE rated
Mounting
DIP
Pins
40
Pitch
1.78 mm
Electrical
ParameterValue
Isolation voltage
1500 Vrms
Values from published data for this part (parameters, FAQ and evaluation report). The datasheet prevails.
WHD40103GNeed samples, or a value that is not in this table? Ask our FAE team.
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02Applications
Where WHD40103G is used
- Switches and routers
- Wireless access points
- IP cameras
- Industrial control devices
Typical application
The transformer isolates the PHY from the cable and couples the TX and RX differential pairs to the RJ45 jack.
Center-tap biasing on the PHY side depends on the PHY type (voltage-mode or current-mode).
Typical application for reference. Follow the PHY vendor's reference design.
Design notes
- 01Connect the center taps according to your PHY type.Voltage-mode and current-mode PHYs need different center-tap biasing; a mismatch can break auto-negotiation.Check with your PHY →
- 02Terminate the line-side center taps with a Bob Smith network.It gives common-mode noise a defined path to chassis ground and helps EMC.
- 03Add line-side surge protection for outdoor or long-cable ports.Residual surge energy through the transformer can still damage the PHY.Troubleshooting guide →
Reference designs by application:Industrial ControlSecurity MonitoringData Communication
WHD40103GNot sure it fits your PHY and layout? An engineer can check your design.
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03Documents
Datasheet, CAD and reports
-
WHD40103G Datasheet (PDF)2024-11-22 · This part Download ↓
-
3D model (STEP)2026-06-03 · This part Download ↓
-
PCB Layout / Package2025-12-29 · This part Download ↓
-
LAN Transformer Reliability TestLatest · Product family View →
-
LAN Transformer EU RoHS ReportLatest · Product family View →
-
REACH SVHC test reportLatest · Communication electronic components View →
WHD40103GNeed another file format, or samples to test? Ask our FAE team.
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04Quality
Quality and compliance
DocumentNo.Issued / tested byDateApplies toActions
Certificate
Certificate · Company
ISO 9001:2015No. 19826Q02503R101
Quality management systemBeijing Xinjiyuan Certification Co., Ltd.Valid 2026-10-17 to 2029-10-16
19826Q02503R101
Beijing Xinjiyuan Certification Co., Ltd.
Valid2026-10-17 to 2029-10-16
Company
View PDF →
Verify →
Scope: R&D and sales of precision electronic connectors
Certificate
Certificate · Company
ISO 14001:2015No. 19826E01323R101
Environmental management systemBeijing Xinjiyuan Certification Co., Ltd.Valid 2026-10-17 to 2029-10-16
19826E01323R101
Beijing Xinjiyuan Certification Co., Ltd.
Valid2026-10-17 to 2029-10-16
Company
View PDF →
Verify →
Scope: R&D and sales of precision electronic connectors
Test report
Test report · LAN transformers
EU RoHSNo. WTH26H06190301C
2011/65/EU and (EU) 2015/863, 10 substancesWaltek Testing Group HCT (Shenzhen) Co., Ltd.Issued 2026-07-31
WTH26H06190301C
Waltek Testing Group HCT (Shenzhen) Co., Ltd.
Issued2026-07-31
LAN transformers
View PDF →
Test report
Test report · Communication electronic components
REACH SVHCNo. WTH26H06167853C
253 substancesWaltek Testing Group HCT (Shenzhen) Co., Ltd.Issued 2026-07-01
WTH26H06167853C
Waltek Testing Group HCT (Shenzhen) Co., Ltd.
Issued2026-07-01
Communication electronic components
View PDF →
ISO certificates cover VOOHU's management systems. RoHS and REACH test reports cover tested samples of each product family.
05Ordering
Ordering and delivery
06Compare
Same-series Comparison
Red marks values that differ from this part; data from the published parameters of each part.
Data rate
10/100BASE-TX
10/100BASE-TX
10/100BASE-TX
Mounting
DIP
DIP
DIP
Ports
Quad port
Triple port
Five port
Pins
40
30
72
Pitch
1.78 mm
2.0 mm
1.78 mm
Operating temperature
0 to +70 °C
0 to +70 °C
0 to +70 °C
Isolation voltage
1500 Vrms
1500 Vrms
1500 Vrms
PoE
Not PoE rated
Not PoE rated
Not PoE rated
WHD40103GNot sure which part in the series fits? Ask our FAE team which one to sample.
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07FAQ
FAQ LAN Transformer: WHD40103G
How should the 40PIN package of WHD40103G be mapped to the PHY channels on a four-port board?
Use the internal schematic to map each of the four transmit and receive winding groups to its PHY channel and front-panel port, and retain clear port numbering on the schematic. The four magnetic circuits are independent; do not infer TX/RX or center taps from pin order alone. On the first board, verify polarity, link establishment, and port-indicator logic for every port.
Which dimensions prevent the through-hole footprint of WHD40103G from sharing a conventional 40PIN IC footprint?
WHD40103G is a long, quad-port magnetic module with an approximately 37.80 ± 0.50 mm × 7.80 ± 0.50 mm body and a maximum height of 11.00 mm. Pin pitch is 1.78 mm, row spacing is 4.80 mm, recommended hole diameter is 0.90 mm, and the longitudinal pin span is 33.82 mm. The same pin count does not make the hole pattern, row spacing, or outline compatible.
How should the wave-soldering window of WHD40103G be used during mass-production setup?
Use preheating at 100-110 °C for 60-90 s and peak soldering at 255-265 °C for 3-5 s as the initial component-side window. Before mass production, measure temperature on the actual board with its real thickness, copper area, and carrier, and inspect all 40 pins for solder fill, bridging, and thermal shadowing. Solder-pot setpoints alone do not establish the component's actual thermal exposure.
08Support
Talk to an engineer
01Replace your current partSend the part number you use today. An engineer compares pinout, package and electrical ratings and lists the differences.Start a replacement review →
02Match it to your PHYTell us your PHY. We check center-tap wiring, termination and the matching RJ45 jack.Check my design →
03Link drops, hi-pot or EMC failuresSend the symptoms and test conditions. Get an FAE-reviewed troubleshooting checklist.Start troubleshooting →
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- VOOHU
- Founded in 2018
- Suzhou, China
- 1,500+ customers
- FAE support
Typical application
