I have worked for three years for a cellphone charger manufacturer and designed a few battery chargers. Almost all of the chargers are Class II devices. Several the cellphone manufacturers specifically stated in their specifications that the use of the so called Y capacitors was not allowed because some phone models had metal housings.
A Y capacitor is a safety capacitor put across the SMPS transformer, between primary and secondary. It is used for EMI reduction. The problem is that it creates a path between the primary side (AC mains) and the secondary side (load, in this case the cellphone), and the resulting leakage current is high enough for the cellphone user to feel an uncomfortable tingle while holding a phone connected to the charger.
All notebook power supplies that I have disassembled are Class I devices, and all have Y capacitors. Moreover, they have an electrical connection between the protective earth prong on the AC inlet and the DC ground (-) on the output. In that case, if the AC socket is properly grounded, the leakage current through the Y capacitor is diverted to earth and the user feels no tingle. On the other hand, if the protective earth of the SMPS is disabled or not properly connected, it behaves just like a Class II device equipped with a Y capacitor, and the notebook user will feel the tingle.
Slashdot Mirror
Didn't Tag Heuer have some phone models with saphire displays?
Hmm, 3 atoms for the LED and a million atoms for each solder joint.
What is the marketing department smoking?
Well, considering their naming scheme, I would guess marijuana.
I have worked for three years for a cellphone charger manufacturer and designed a few battery chargers. Almost all of the chargers are Class II devices. Several the cellphone manufacturers specifically stated in their specifications that the use of the so called Y capacitors was not allowed because some phone models had metal housings. A Y capacitor is a safety capacitor put across the SMPS transformer, between primary and secondary. It is used for EMI reduction. The problem is that it creates a path between the primary side (AC mains) and the secondary side (load, in this case the cellphone), and the resulting leakage current is high enough for the cellphone user to feel an uncomfortable tingle while holding a phone connected to the charger. All notebook power supplies that I have disassembled are Class I devices, and all have Y capacitors. Moreover, they have an electrical connection between the protective earth prong on the AC inlet and the DC ground (-) on the output. In that case, if the AC socket is properly grounded, the leakage current through the Y capacitor is diverted to earth and the user feels no tingle. On the other hand, if the protective earth of the SMPS is disabled or not properly connected, it behaves just like a Class II device equipped with a Y capacitor, and the notebook user will feel the tingle.