Mobile Multi-Output PWM Controller with Virtual Current Sense Description The SC1403 is a multiple-output power supply controller designed to power battery operated systems. The SC1403 provides synchronous rectified buck converter control for two (3.3 V and 5 V) power supplies. An efficiency of 95% can be achieved for the two supplies. The SC1403 uses Semtech’s proprietary Virtual Current SenseTM technology along with external error amplifier compensation to achieve enhanced stability and DC accuracy over a wide range of output filter components while maintaining fixed frequency operation. The SC1403 also provides a linear regulator for system housekeeping. The 5 V linear regulator takes its input from the battery; for efficiency, the output is switched to the 5V output when available. Control functions include: power up sequencing, soft start, power-good signaling, and frequency synchronization. Line and load regulation is to +/-1% of the output voltage. The internal oscillator can be adjusted to 200 kHz or 300 kHz or synchronized to an external clock. The MOSFET drivers provide >1A peak drive current for fast MOSFET switching. The SC1403 includes a PSAVE# input to select pulse skipping mode for high efficiency at light load, or fixed frequency mode for low noise operation. Features - 3.3V and 5V dual synchronous outputs, resistor programmable to 2.5V - Fixed frequency or PSAVE for maximum efficiency over wide load current range - 5V / 50mA linear regulator - Virtual Current Sense TM for enhanced stability - Accurate low loss current limiting - Out of phase switching reduces input capacitance requirements - External compensation supports wide range of output filter components - Programmable power-up sequence - Power good output - Output overvoltage & overcurrent protection with output undervoltage shutdown - 4μA typical shutdown current - 6mW typical quiescent power Applications - Notebook and subnotebook computers - Automotive electronics - Desktop DC-DC converters Note: (1) This device is ESD sensitive. Use of standard ESD handling precautions required. (2) Only available in tape and reel packaging. A reel contains 2500 devices.