Switcher ICs Run From AC Power Line

Converting off-line, 230 Vac voltages to dc levels is the function of two families of switcher ICs targeted at consumer, industrial and home appliance markets. The STR-A61xx series is designed for low output power (up to 20W) applications at 230 Vac input. They have an auto-standby function enabled by burst-mode operation that reduces power consumption to less than 50 mW at 230 Vac. Protection features include over-voltage, over-current, overload and thermal shut down. The STR-W67xx devices are quasi-resonant topology types that feature low EMI noise characteristics at frequencies above 2 MHz. They have a bottom-skip function that skips the first bottom point of VDS and turns on the power MOSFET at the second bottom to minimize increasing the operational frequency at light loads. Two standby functions reduce the input power at very light output load conditions. STR-A61xx types come in an 8-pin DIP, while the STR-W67xx are housed in a 6-pin SIP. Prices for the STR-A61xx devices range from $0.58 to $0.85 and from $1.33 to $1.85 for the STR-W67xx, each/1,000. For further details, call. ALLEGRO MICROSYSTEMS INC., Worcester, MA. (508) 853-5000