Fairchild's power switch improves off-line power supply designs

SAN JOSE, USA: Responding to customer needs for solutions that can provide lower standby power consumption and easier design in off-line power supplies, Fairchild Semiconductor has developed the only power switch in the industry that integrates drain-current sensing in a 650V internal avalanche-rugged SenseFET, reducing power dissipation and improving reliability by shortening the over-current time delay to less than 200 ns.

This FPS power switch for off-line power supplies up to 60 Watts (for universal AC input) – the FSGM0565R – achieves exceptional standby power consumption in a 66 kHz flyback converter: 120 mW at 265 VAC in with 25 mW of load. This is enabled by the SenseFET, a high-voltage startup circuit that turns off the startup resistor, and “soft burst” operation in standby, saving 30mW and preventing the converter from generating audible noise.

Many protection features are built-in, all with auto-restart, to reduce component count in the power supply, providing designers with greater value and higher reliability. These include overload protection, over-voltage protection, abnormal over-current protection, internal thermal shutdown with hysteresis, output short protection and under-voltage lockout.

The combination of low component count and high reliability makes this power switch attractive for many applications including LCD TVs and monitors—especially four-lamp LCD monitors.

Other advanced features include a wide supply-voltage range (12 to 24 VDC), built-in 15 ms soft-start and enhanced lightning surge immunity.

The FSGM0565R, available in a 6-lead TO-220F package, is part of the Fairchild Power Switch (FPS) portfolio that offers design engineers many choices of integrated controllers and MOSFETs with complete circuit protection for power levels from a few Watts to a few hundred Watts.

It is priced at $1 each, with minimum orders starting at 1k pieces. Delivery takes six to eight weeks. Samples are available now.