The UC3572 is a negative output flyback pulse width modulator which converts a positive input voltage to a regulated negative output voltage. The chip is optimized for use in a single inductor negative flyback switching converter employing an external PMOS switch. The block diagram consists of a precision reference, an error amplifier configured for voltage mode operation, an oscillator, a PWM comparator with latching logic, and a 0.5A peak gate driver. The UC3572 includes an undervoltage lockout circuit to insure sufficient input supply voltage is present before any switching activity can occur, and a pulse-by-pulse current limit. Output current can be sensed and limited to a user determined maximum value. The UVLO circuit turns the chip off when the input voltage is below the UVLO threshold. In addition, a sleep comparator interfaces to the UVLO circuit to turn the chip off. This reduces the supply current to only 50uA, making the UC3572 ideal for battery powered applications.
|Part number||Order||Vin (Min) (V)||Vin (Max) (V)||Vout (Min) (V)||Vout (Max) (V)||Regulated outputs (#)||Switching frequency (Min) (kHz)||Switching frequency (Max) (kHz)||Iq (Typ) (mA)||Features||Duty cycle (Max) (%)||Operating temperature range (C)||Type||Rating||Package Group|
||4.2||35||-70||-1||1||10||200||9||100||-40 to 85||Controller||Catalog||SOIC | 8|