Buck Converters Ready For Cramped Environments

Positioned for ultra-small battery-powered products, the Si91xx 600-mA synchronous buck converters promise to prolong run-times of single-cell Li-ion batteries. The Si9174, Si9175, and Si9176 convert 2.6V to 6V input voltages to output voltages as low as 0.4 V and operate at a maximum PWM switching frequency of 2 MHz. These features are said to significantly reduce output capacitor and inductor size. Integrated power MOSFETs reduce external components to one inductor, three capacitors, and two resistors. Other features common to the three converters include 100% duty cycle control, selectable PWM, PSM, and an auto mode for automatic shifting between PWM and PSM. The Si9174 and Si9175 can be synchronized to a 13-MHz external oscillator to reduce noise and the Si9174 includes a d/a converter input for output voltage adjustments from 0.4V up to the input voltage. The Si9175 and Si9176 have a fixed output voltage down to 1.2V set by external resistors. All three include thermal shutdown, undervoltage lock-out, and overcurrent protection and are rated for operation over a temperature range from -40ÞC to +85ÞC. Available in an MSOP-10 or a leadless MLP33 measuring 3 mm x 3 mm, price is $1.30 each/50,000. INTERTECHNOLOGY INC., Malvern, PA. (610) 644-1300.