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High Voltage Switching Regulator SMD912 Isolation Controller SMD912 FEATURES DESCRIPTION Operate from a rectified 85~265 VAC line The SMD912 is a monolithic high voltage switching source. regulator-controller with PWM/PFM control that is Typical oscillation frequency: 90 kHz specifically designed to operate from a rectified Output voltage external setting (FB) type 85~265 VAC line source. available. FB terminal voltage (VFB) 1.0 V. This device contains a reference voltage source, Duty ratio: 0% to 5% typ.- PFM control, 5% to oscillation circuit, error amplifier, phase 85% typ. - PWM control compensation circuit, PWM control circuit, power Built-in current limiting circuit: Assigned by supply 450 V MOS-transistor, and other external resistor. components. Since the oscillation frequency is at Over voltage protection high 90 kHz, with the addition of a small external Under voltage protection component, the IC can function as switching Soft-start function: Built-in Soft-start circuit. regulator with high efficiency. Built-in current source. The SMD912 provides low-ripple power, high-efficiency, and excellent transient characteristics because of the PWM control circuit being capable of varying