Power Management IC SG3525AP013TR SOIC-16 Switching Controller integrated circuit SG3525

The SG3525A series of pulse width modulator inte grated circuits are designed to offer improved performance and lowered external parts count when used in designing all types of switching power sup plies. 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 the CT and the discharge terminals provide a wide range of dead time ad- justment.

These devices also feature built-in soft-start circuitry with only an external timing capacitor required. A shutdown terminal controls both the soft-start circuity and the output stages, providing instantaneous turn off through the PWM latch with pulsed shut down, as well as soft-start recycle with longer shutdown commands. These functions are also control led by an undervoltage lockout which keeps the out puts off and the soft-start capacitor discharged for sub-normal input voltages.

This lockout circuitry in cludes approximately 500 mV of hysteresis for jitterfree operation. Another feature of these PWM cir cuits is a latch following the comparator. Once a PWM pulses has been terminated for any reason, the outputs will remain off for the duration of the period. The latch is reset with each clock pulse. The output stages are totem-pole designs capable of sourcing or sinking in excess of 200 mA. The SG3525A output stage features NOR logic, giving a LOW output for an OFF state.