The UC1525A/1527A series of pulse width modulator integrated circuits are designed to
offer improved performance and lowered external parts count when used in designing all types of
switching power supplies. The on-chip 5.1-V reference is trimmed to 1% and the input common-mode
range of the error amplifier includes the reference voltage, eliminating external resistors. A sync
input to the oscillator allows multiple units to be slaved or a single unit to be synchronized to
an external system clock. A single resistor between CT and the discharge
terminals provides a wide range of dead-time adjustment. These devices also feature built-in
soft-start circuitry with only an external timing capacitor required. A shutdown terminal controls
both the soft-start circuitry and the output stages, providing instantaneous turn off through the
PWM latch with pulsed shutdown, as well as soft-start recycle with longer shutdown commands.
