The UCC2809D-1 is a BCDMOS low power economy primary side Pulse Width Modulation (PWM) Controller contains all the control and drive circuitry required for off-line and isolated DC to DC fixed frequency current-mode switching power supplies with minimal external parts count. Internally implemented circuits include undervoltage lockout featuring startup current less than 100μA, user accessible voltage reference, logic to ensure latched operation, a PWM comparator and a totem pole output stage to sink or source peak current. The output stage, suitable for driving N-channel MOSFETs, is low in the off state. Oscillator frequency and maximum duty cycle are programmed with two resistors and a capacitor. The family has UVLO thresholds and hysteresis levels for off-line and DC-to-DC systems as shown in the table to the left.
User programmable soft start with active low shutdown
(EN)
