DESCRIPTION
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 betweenthe CT andthe dischargeterminals provide a wide range of dead time ad- justment. Thesedevicesalso featurebuilt-insoft-startcircuitry with only an external timing capacitor required. A shutdownterminal controls both the soft-start circuity 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. These functions are also controlled by an undervoltagelockoutwhich keepsthe outputs off and the soft-start capacitor discharged for sub-normal input voltages. This lockout circuitry includesapproximately 500 mV of hysteresisfor jitterfree operation. Another feature of these PWM circuits 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.
STMicroelectronics
