Dual-Output Buck Controller Delivers Flexible Start-up / Shutdown Tracking

With built-in soft-start pins, the SC416 grants designers the flexibility to track voltage levels in ratiometric, concentric and independent modes. This capability benefits applications where the voltage differential between supply rails must meet defined limits during operating conditions. It can also be used for processors with multiple power rails, to protect the downstream IC from excessive power dissipation caused by the interaction of ramping power supplies during start-up or shutdown. Employing the voltage tracking option can also reduce system costs by eliminating the need to over-specify power rails to accommodate excess power dissipation.

For applications requiring tracking of more than two voltage levels, multiple SC416 devices can be linked together.

The SC416 incorporates Semtech’s unique Smart-Drive™ circuitry to reduce electromagnetic interference (EMI). The reduced EMI levels achieved from this approach contribute to a system-wide EMI reduction effort to ensure compliance with FCC regulations. The SC416 also features programmable current limit, output over-voltage protection, over-temperature protection, and input under-voltage lockout.

Automatic power-save is built into the SC416 to maintain very high efficiency in light-load conditions. The power-save capability monitors the inductor current and shuts off the low-side FET on a cycle-by-cycle basis to prevent reverse current. Added to this is the Semtech Smart Power-Save, which monitors the high-side FET for leakage or for a load dump, and will disengage the power-save capability temporarily to protect the integrity of the output voltages.

The device is based on Semtech’s constant on-time technology, a pseudo fixed-frequency technology that senses a change in load or line voltage and adjusts its pulse density to match the change. This fast response to electrical transients minimizes output capacitance, requiring no compensation if the minimum ESR requirements are met.

“With three tracking modes, the SC416 gives the designer the flexibility and features needed to develop the power-up and power-modes best suited to the system design,” said Ramesh Balasubramaniam, Marketing Manager for Semtech’s Portable Power Management Products Group. “The SC416 also features our best buck controller technology to drive efficiency and lower EMI, both of which are critical to portable devices that need long battery life and compliance to FCC standards.”