UC3573 Buck Pulse Width Modulator Stepdown Voltage Regulator | TI.com

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Buck Pulse Width Modulator Stepdown Voltage Regulator



The UC3573 is a Buck pulse width modulator which steps down and regulates a positive input voltage. The chip is optimized for use in a single inductor buck 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 UC3573 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. Input current can be sensed and limited to a user determined maximum value. In addition, a sleep comparator interfaces to the UVLO circuit which turns the chip off when the input voltage is below the UVLO threshold. This reduces the supply current to only 50uA, making the UC3573 ideal for battery powered applications.


  • Simple Single Inductor Buck PWM Stepdown Voltage Regulation
  • Drives External PMOS Switch
  • Contains UVLO Circuit
  • Includes Pulse-by-Pulse Current Limit
  • Low 50µA Sleep Mode Current


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Part number Order Vin (Min) (V) Vin (Max) (V) Vout (Min) (V) Vout (Max) (V) Iout (Max) (A) Regulated outputs (#) Number of Phases Switching frequency (Min) (kHz) Switching frequency (Max) (kHz) Iq (Typ) (mA) Features Duty cycle (Max) (%) Operating temperature range (C) Rating Package Group Type Control mode
UC2573 Order now 4.2     35     1.5     30     0.5     1     1     200     300     9     Enable     100     -40 to 85     Catalog     SOIC | 8     Controller     Voltage Mode