Efficient offline power converters for consumer applications

July 29, 2014 // By Graham Prophet
Integrated 650V avalanche-rated MOSFETs enable robust, compact switching solutions for power-hungry applications such as household appliances, DVD players and set top boxes.

Three current mode, fixed frequency switching regulators are added to ON Semiconductor's power management products. For compact, high reliability offline AC-DC switched-mode power supplies, the NCP1129, NCP1126, and NCP1124 incorporate an avalanche-rated 650V MOSFET and frequency foldback along with skip mode that improve light load and standby efficiency, meeting the ENERGY STAR EPS 2.0 Standard.

The high degree of integration results in minimal external components, suiting them to power system designs for household appliances, DVD players and set-top boxes. The NCP1129, NCP1126, and NCP1124 can deliver up to 25W, 15W and 12W respectively and each generates a jittered 65 kHz or 100 kHz switching frequency, for improved EMI performance.

Maximum peak current is adjustable via an external resistor, facilitating ramp compensation, so that stable continuous conduction mode (CCM) operation can be maintained. The frequency foldback mode permits power conversion efficiency levels to be raised under light load conditions, while the skip mode can be activated for reducing standby power consumption at (or close to) a no load scenario - with less than 100 mW drawn at high line when in standby mode.

The NCP112x devices all have protection features including a 50 msec timer-based auto-recovery short-circuit protection function. Short-circuit fault conditions can be independently detected from the auxiliary winding voltage, ensuring comprehensive safeguards against short-circuit occurrences. The devices incorporate built-in thermal shutdown and over-voltage response mechanisms, as well as a 2 kV human body model (HBM) resilience rating to electrostatic discharge. Temperature range is -40 °C to +150°C; in a PDIP-7 package pricing starts at $0.32 (1000).

ON Semiconductor; www.onsemi.com