UC3572 Negative Output Flyback Pulse Width Modulator | TI.com


Negative Output Flyback Pulse Width Modulator

Negative Output Flyback Pulse Width Modulator - UC3572


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.


  • Simple Single Inductor Flyback PWM for Negative Voltage Generation
  • Drives External PMOS Switch
  • Contains UVLO Circuit
  • Includes Pulse-by-Pulse Current Limit
  • Low 50uA Sleep Mode Current


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Part number Order Topology Vin (Min) (V) Vin (Max) (V) Vout (Min) (V) Vout (Max) (V) Duty cycle (Max) (%) Switching frequency (Min) (kHz) Switching frequency (Max) (kHz) Iq (Typ) (mA) Features Iout (Max) (A) Operating temperature range (C) Rating Package Group
UC2572 Order now Inverting     4.2     35     -70     -1     100     10     200     9    
10     -40 to 85     Catalog     SOIC | 8