X-Capacitor discharge ICs gain IEC 62368 certification for TV/IT equipment

September 12, 2014 // By Graham Prophet
These simple, self-powered two-terminal devices automatically and safely eliminate losses in power-supply EMI filters.

Power Integrations' CAPZero family of two-terminal, automatic X-capacitor discharge ICs has been certified to meet IEC 62368, the new over-arching safety standard covering TVs and IT equipment. The CAPZero family eliminates power losses while allowing power supplies to comply with safety standards. The new standard replaces IEC 60950 and IEC 60065 and will become mandatory.

CAPZero ICs are smart, high-voltage switches that are placed in series with the resistors used to provide a safe discharge path for a power supply’s X capacitor. The alternative to using such a switching device is to use constantly-connected discharge resistors alone, which cause a constant power drain while AC is connected and therefore contribute significantly to no-load and standby input power consumption. CAPZero X-capacitor discharge ICs block current flow to the discharge resistors when AC voltage is applied, cutting the power wasted in these components to zero. When the AC voltage is disconnected, CAPZero automatically and safely discharges the X capacitor by closing the circuit and directing the energy away from the exposed AC plug.

Comments Edward Ong, product marketing manager at Power Integrations: "Once the new standards reach a mandatory phase, mains-voltage electrical equipment must carry the IEC 62368 certification. CAPZero ICs are certified to the new standard and deliver a simple, cost-effective solution to eliminate discharge resistor loss while requiring minimal modification to system or PCB layout. This approach allows engineers total flexibility in their choice of the X capacitor used, optimising differential-mode EMI filtering and providing a highly cost-effective option for designers optimising no-load consumption, power factor, and EMI, as well as meeting the most up to date safety regulations.”

CAPZero ICs can be used before or after the system input fuse, as the X-capacitor discharge ICs inherently meet international safety standards for all open- and short-circuit fault tests. Devices are suitable for all AC-DC converters with X capacitors, and are available with 825V or 1000V MOSFETs to support a variety