Semtech announced the release of two synchronous, pulse-width-modulation (PWM) buck controllers with integrated voltage-transitioning switches for on-the-fly voltage output changes and voltage margining, dubbed the SC471(A) and SC475A. The SC471(A) features two FET switches which allow the output to change dynamically between a maximum of four different levels. It can be used as a voltage-margining controller for the functionality and reliability testing of a system at upper and lower power-supply voltage limits. The device can also be used with graphics processors or microprocessors requiring more than two input voltage levels for normal operation and sleep modes.
The SC475A controller has one FET switch that dynamically changes the output voltage for processors that require different voltages for normal operation and for sleep mode. The powergood output is blanked during output-voltage transitions in order to eliminate the potential for glitches.
Both high-efficiency devices feature a constant on-time topology for a fast, transient response, requiring less output capacitance than competing fixed-frequency converters. The devices also employ Semtech's patent-pending Smart Power- Save mode for protecting the downstream device from high voltage levels due to leakage or load dump.