Semtech - 28V Regulators to Synchronous Buck Regulator Platform

The SC414/SC424 have a wide input voltage range of 3V to 28V and achieve high efficiencies over an extended load range. The fixed 5V LDO can be used to provide the power for the gate drive bias, allowing the part to operate from a single rail. For optimum efficiency, the internal crossover circuitry bypasses the LDO after startup, if the LDO and buck outputs are the same. Pseudo fixed frequency adaptive on-time control gives the part excellent transient response, reduces the output filter capacitance required and greatly simplifies the design process by removing external compensation components.

SC414 and SC424 regulators also feature attractive power save functions. Selectable ultrasonic power save for the SC414 allows the device to operate in discontinuous conduction mode at light load conditions, saving quiescent current, while limiting the “floor” frequency to avoid audible noise.

The SC424 has regular power save with no “floor” frequency, for maximum light load efficiency. Both devices have the same pin out and can be readily interchanged should system requirements change.

Semtech’s Smart Power Save technique enables these devices to re-enter continuous conduction mode when active loads attempt to pull the output high while in power save mode, pulling the output back down and avoiding over voltage latch-off.

Like the SC417 and SC427, the SC414 and SC424 also feature temperature compensated RDS(ON) sensed current limit, which effectively doubles the current limit precision.

“The SC414 and SC424 6A buck regulators complement the SC417 and SC427 very nicely, adding a smaller solution for lower current point-of-load applications with the same flexibility and ease of use that are already so popular. Having pin-to-pin compatible ultrasonic and regular power save versions makes it simple to change designs downstream as requirements change,” said Alan Burchfield, Senior Product Marketing Manager for Semtech’s Power Management Group. “The wide input operating range, single input rail capability, and compact package, along with high efficiency over the entire load range make them broadly applicable to applications such as ultra mobile, industrial and notebook PCs, wireless base stations, multi-function printers, and digital TV.”

The SC414 and SC424 have built-in soft-start, cycle-by-cycle current limiting, over-temperature, and over- and under- voltage protection features. They also include a power good output for the switching regulator, which may be used for diagnostics and sequencing.