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 ~ 400KHZ 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