Application of isolation transformer in USB interface circuit

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

TP-IP4220CZ6 5V 0.35PF breakdown voltage 6V SOT

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Photocoupler

In the circuit shown, H102 is a network isolation transformer. However, it's often misused by grounding both sides of the transformer. Originally, the purpose of an isolation transformer was to separate the system from the transmission line, providing electrical isolation. But when both sides are grounded, this common ground allows high-frequency interference to still pass through, significantly reducing the effectiveness of the isolation. This can lead to signal distortion or noise in sensitive systems. To avoid this issue, it's important to ensure that the isolation transformer is used correctly, with only one side grounded if necessary. Proper implementation ensures better noise suppression and system stability.