USB Charger

Author	Message
Mixtel90 Guru Joined: 05/10/2019 Location: United Kingdom Posts: 8964	Posted: 08:36am 10 Oct 2023       I think that regardless of Class I or Class II isolation, the test would still be to mains earth on the LV side. The difference is that in Class II there should be an additional insulating barrier in case the primary one should fail. The Class II charger shown *should* have basic (wire insulation) and reinforced (additional insulation layer) insulation on the transformer with an opto-isolator or additional insulated winding for feedback. Additionally the PCB should be able to withstand the isolation voltage. UL regulations state this as twice the working voltage + 1000 volts for 1 second. The UK says that the resistance should be greater than 1M when measured using 500V AC between mains input and LV output. Edited 2023-10-10 18:42 by Mixtel90