SC411

The SC411 is a constant on-time synchronous buck PWM controller in a space-saving MLPQ package intended for use in notebook computers and other battery operated portable devices. Features include high effi ciency and a fast dynamic response with no minimum on-time. The excellent transient response means that SC411 based solutions will require less output capacitance than competing fi xed frequency converters.

The switching frequency is constant until a step-in load or line voltage occurs. During this time the pulse density and frequency will increase or decrease to counter the change in output or input voltage. After the transient event, the controller frequency will return to steady-state operation. At light loads, Powersave Mode enables the SC411 to skip PWM pulses for better effi ciency.

The output voltage can be adjusted from 0.5V to VCCA. A frequency setting resistor sets the on-time for the controller. The integrated gate drivers feature adaptive shoot-through protection and soft-switching. Additional features include cycle-by-cycle current limit, digital soft-start, over-voltage and under-voltage protection, a Power Good output and soft discharge upon shutdown.