1A Synchronous Buck Regulator for Portables

6th July 2006

ES Admin

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Semtech has announced the SC194A, a highly integrated 1A DC-DC step-down (buck) regulator with the small size and output flexibility needed for portable device applications. The SC194A has an input voltage range from 2.7V to 5.5V with a focus on portable applications that use Li-ion batteries. The device uses two programming pins to allow users to set the output voltage to 1.0V, 1.2V, 1.5V or 1.8V. 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 SC194A goes beyond the voltage programming pins which eliminate the need for voltage-setting resistors on the output. The device includes an internal compensation network, integrated switching Field Effect Transistors (FETs) and eliminates the need for an external Schottky diode. Complete power regulation is achieved using only the SC194A and three discrete components, giving the user four output voltage options with a minimal bill of materials.

The flexible clocking scheme allows the user 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 SC194A is designed for high efficiency at all loads to maximize the battery life. The device features up to 93% maximum efficiency at 1.8V output over a broad range. 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.

The SC194A 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 SC194A comes in a 3mm x 3mm lead-free and RoHS compliant MLP-10 package.