Case Study – Helping a 65W PD Charger Pass Safety & EMC Testing

The Challenge

A charger manufacturer encountered repeated EMC noise issues while developing a 65W PD adapter.

To reduce high-frequency common-mode noise, the engineering team increased the Y capacitor from 1,000pF (102) to 2,200pF (222). However, the output ripple did not improve. Worse, the adapter failed the leakage current test during safety certification.

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JEC Analysis

JEC’s FAE team analyzed the circuit and found that the oversized Y capacitor increased the leakage current and created an unintended path for high-frequency noise coupling.

JEC Solution

JEC recommended the JD-102M-Y1 safety Y capacitor and optimized the transformer shielding design.

After the adjustment, the customer’s product successfully passed both safety and EMC testing.

The right Y capacitor is not simply about higher capacitance. It requires the right balance between EMI performance and safety.

JEC provides UL, VDE, CQC, ENEC and other international certified safety capacitors, backed by engineering support for power supply applications.

Need help selecting the right safety Y capacitor? Contact JEC for free samples and engineering support.