Cordless telephone linear power adapter designed with LNK562PN, with circuit diagram, bill of materials, transformer specification file, printed

Photocoupler

Summary:

Way of working

Power supplies for cordless phones or answering devices typically require a 10 kV common mode lightning strike to prevent lightning from damaging the telephone network. The circuit diagram is designed to meet this requirement and has the advantages of simple design and low cost.

The LNK562 device (U1) eliminates the optocoupler by detecting the output voltage and current at the primary. Shielded windings have been included in the transformer design when using PI transformer design software. This allows the circuit to meet the EN55022B conducted EMI limit without the use of a jumper Y capacitor between the primary and secondary insulation.

design feature

• CV/CC solution with simple design, low cost and few component counts
• Low no-load power consumption, no-load power consumption <180 mW at 265 VAC input
• Significantly improved adjustment rate compared to power frequency linear transformers
• Meet CEC/Energy Star efficiency requirements for on-load mode of operation (63% vs. 53% required)
• Small, low-cost EE16 core for compact design
• EMI margin >15 dBμV compared to EN55022B conducted EMI limits
• No Y capacitor: power frequency leakage current <10 μA
• Meets 10 kV common mode and 2 kV differential mode surge (EN 1000-4-5 Class 4)

Cordless phone linear power adapter PCB physical map

Cordless telephone linear power adapter circuit diagram

Cordless phone linear power adapter PCB layout

Cordless phone linear power adapter component list

See the uploading documentation for details (click to download)