New offline switcher ICs integrate lossless zero-cross detection and X-capacitor discharge functions

The LinkSwitch™-TNZ power supply ICs, which support loads of up to 12 W, save space and power in devices such as light switches, eliminating the need for multiple discrete components, and greatly reducing standby power consumption.

Power Integrations has introduced the LinkSwitch™-TNZ, a switching power supply IC family which combines offline power conversion, lossless zero-cross detection, and an optional X-capacitor discharge function in a single chip which is housed in a compact SO-8C package. 

The highly efficient LinkSwitch-TNZ IC can be used for non-isolated buck and buck-boost power supplies providing up to 575 mA output current. It supplies up to 12 W of power in universal mains-input, isolated flyback designs.

The LinkSwitch-TNZ integrated zero-cross detection function helps power-system designers to save both power and space. The detection circuit consumes less than 5 mW. Other approaches require ten or more discrete components and typically consume between 50 mW and 100 mW of continuous power, which often accounts for almost half of the system standby power budget. 

By providing a low-power zero-cross detection function, the LinkSwitch-TNZ gives devices such as light switches, dimmers, sensors, and plugs a new, more efficient way to control the turn-on transition of the main power device while reducing switching losses and in-rush current. 

LinkSwitch-TNZ ICs provide excellent efficiency at light loads. By using the LinkSwitch-TNZ, OEMs can more easily comply with the stringent regulations governing standby power consumption, such as the European Commission regulation 1275 for home appliances, the US ENERGY STAR standard for smart home energy management systems, and China’s GB 24849, which limits the off-mode power consumption in microwave ovens to 0.5 W. 

LinkSwitch-TNZ switching power supply ICs achieve ±3% regulation accuracy across line and load. No-load power consumption is less than 30 mW with an external bias. Standby current is less than 100 µA. 

An optional X-capacitor discharge function can be included in LNK331x LinkSwitch-TNZ ICs for high-power applications, giving even more PCB space savings, reducing component count and increasing system reliability.

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