W6750

Application Note 28103.30 SwRitecghuinlagtors PRODUCT DESCRIPTION Series STR-W6750 Off-Line Quasi-Resonant Switching Regulators INTRODUCTION The Series STR-W6750 devices are hybrid integrated circuits (HICs) with a built-in power MOSFET and a control IC designed for quasi-resonant type switch-mode power supplies (SMPS). In normal operation, the HIC provides high efficiency and low EMI noise with bottom-skip quasi-resonant operation during light output loads. Low power consumption is also achieved by blocking (intermittent) oscillation during an auto-burst mode and reduced even further in a manually triggered (clamping an output voltage) standby mode. The HIC is supplied in a seven-pin fully-molded TO-220-style package with pin 2 deleted, which is suitable for downsizing and standardizing of an SMPS by reducing external component count and simplifying circuit design. Features Blocking (or intermittent) oscillation operation by reducing output voltage in the standby mode. In addition to the standard quasi-resonant operation, a bottom-skip function is available for increased efficiency from light to medium load. Soft-start operation at start-up. Reduced switching noise (compared to conventional PWM hard-switching solution) with a step-drive function. Built-in avalanche-energy-guaranteed power MOSFET (to simplify surge-absorption circuit; no VDSS derating is required). Overcurrent protection (OCP), overvoltage protection (OVP), overload protection (OLP), and maximum ON-time co...