Buck Converters Offer Digital Programmable and Externally Adjustable Output Voltage Options
Semtech’s SC196 and SC196A 1.5A DC/DC step-down (buck) regulators feature high efficiency due to low quiescent current and power save modes to target the lower voltage levels needed for next-generation portable device designs. The SC196 uses external feedback to allow the output voltage to be set anywhere between 1V and the input voltage for design flexibility. The SC196A uses two programming pins to set the output voltage to 1V, 1.05V, 1.2V or 1.8V. The voltage control pins can be hard-wired for a constant voltage, or they can be tied to a microcontroller and dynamically switched for applications that use digital power control such as microcontrollers that have lower sleep-state supply voltages. The input voltage ranges of 2.5V to 5.5V for SC196, and 2.7V to 5.5V for SC196A enable the use of many standard voltage rails, including Li-Ion batteries, as a supply for these devices.The devices include an internal compensation network and integrated switching and synchronous MOSFETs that eliminate the need for an external Schottky diode. Complete power regulation is achieved using only the SC196A and three discrete components, giving the user four output voltage options. The flexible clocking scheme of the devices allows the designer to utilize an internal 1MHz fixed clock or connect the device to an external oscillator between 750 kHz and 1.25 MHz for applications requiring a different frequency or clock synchronization. The SC196 devices are designed for high efficiency at all loads to maximize the battery life. The devices feature up to 95 percent maximum efficiency at 3.3V output. A quiescent current of 17 µA, combined with a user-selectable power save mode (PSAVE), allow the device to automatically enter pulse frequency modulation (PFM) at light loads and maintain very high device efficiency.