REGULATING PWM IC
DESCRIPTION
The UTC U3525 is a pulse width modulator IC and designed for switching power supplies application to improve performance and reduce external parts usage.
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. The output stage features NOR logic, giving a LOW output for an OFF state. An under-voltage lockout circuitry, which keeps the outputs off and the soft-start capacitor discharged for sub-normal input voltages, includes approximately 500 mV of hysteresis for jitter free operation. The PWM circuits also feature a latch following the comparator. When a PWM pulses has been terminated, 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 200mA.
FEATURES * Input Voltage: 8~35V * On-chip +5.1V reference is trimmed to ±1% * 100HZ ~ 500KHZ oscillator range * Separate oscillator sync terminal * Adjustable dead time control * Internal soft-start * Pulse-by-pulse shutdown * Input under-voltage lockout with hysteresis * Latching PWM to prevent multiple pulses * Dual source/sink output drivers APPLICATION CIRCUIT  | 
