A family of off-line pulse-width-modulation (PWM) controllers from Allegro MicroSystems incorporates a sense MOSFET and current-mode PWM controller IC. Developed and manufactured by Sanken Electric Co., the STR4A100 series uses a secondary-side regulation topology that suits low-power switch-mode power-supply (SMPS) regulators in white goods and other applications. The devices can lower standby power to less than 10 mW, which could be important in the case of an auxiliary power supply. Automatic switching between the PWM operation in normal operation and burst oscillation under light-load conditions creates the low standby power. Packaging options are DIP-8 and SOIC-8. Specific applications include audio/visual, set-top boxes, and battery chargers.