1A Synchronous Buck Regulator for Portables from Semtech

The SC194B uses two programming pins to allow engineers to set the output voltage to 2.5V, 3.0V, 3.3V or 3.6V. These pins can be hard-wired to set a constant voltage, or they can be tied to a microcontroller and dynamically switched for applications that use digital power control.



The highly integrated feature set of the SC194B goes beyond the voltage programming pins which eliminate the need for voltage-setting resistors on the output. The device includes an internal compensation network, integrates the switching Field Effect Transistors (FETs), and eliminates the need for an external Schottky diode. Complete power regulation is achieved using only the SC194B and three discrete components, giving the user four output voltage options with a minimal bill of materials.



“The SC194B addresses the I/O voltage rail with the same high performance and small size benefits that the SC194A delivers for the microprocessor core voltage,” said Karl Volk, Director of Marketing for Semtech’s Handheld Power Management Group. “Not only do the high efficiency and ultra-low quiescent current reduce heat and extend battery life, but the SC194B’s digitally-controlled output voltage minimizes PCB area by eliminating external feedback while still allowing our customers to purchase and manage inventory for only one device to meet the 2.5V to 3.6V needs of many designs.”



The SC194B is designed for high efficiency at all loads to maximize the battery life. The device features up to 95% maximum efficiency at 3.3V, 200mA output. An automatic power save mode (PSAVE) uses pulse frequency modulation (PFM) at light loads to maintain very high device efficiency. While in PSAVE mode, the device quiescent current is only 17µA. PSAVE mode operation is monitored such that the device automatically detects when to disable this operation or can be manually taken out of PSAVE mode by toggling a single control pin. This is useful in controlling the electrical noise floor created by a switching regulator topology. Additionally, the flexible clocking scheme allows the engineer to select the internal 1MHz fixed clock or connect the device to an external oscillator between 750kHz and 1.25MHz for applications requiring a different frequency or clock synchronization.



The SC194B has built-in soft-start, short-circuit, over voltage and temperature protection features. Furthermore, fast transient reaction protects sensitive loads from extensive supply voltage variations.



The SC194B comes in a 3mm x 3mm lead-free and RoHS compliant MLP-10 package.