Semtech’s Buck Regulator Sports Digitally Controlled Outputs January 2007 Issue Published Date: December 08, 2006
With a focus on portable applications that use Li-ion batteries, the SC194B 1-A, dc/dc, step-down (buck) regulator features an input voltage range of 2.7V to 5V and a programmable output of 2.5V, 3.0V, 3.3V, or 3.6V. The device is a sibling of the SC194A, which has the same features but offers outputs between 1V and 1.8V. Designers can hard-wire the two programming pins to set the desired output voltage or they can tie them to a microcontroller and dynamically switch them for digital power control. These pins eliminate the need for voltage-setting resistors on the output. The highly integrated device also saves board space by including an internal compensation network and switching FETs, and by eliminating the need for an external Schottky diode. Maximum efficiency is 95% at a 3V, 200 mA output. An automatic power-save mode (PSAVE) employs pulse frequency modulation to maintain a high efficiency at light loads. In PSAVE mode, quiescent current is only 17 µA. The device has built-in soft-start, short-circuit, over-voltage, and temperature protection features. In addition, fast transient reaction protects sensitive loads from excessive supply voltage variations. The SC194B comes in a 3 mm x 3 mm lead-free RoHS-compliant MLP-10 package and is priced at $1.69 each/1,000. SEMTECH CORP., Camarillo, CA. (805) 498-2111.
