Fairchild Semiconductor gives system design engineers a highly efficient power management solution for new Dynamic Voltage Scaling (DVS) platforms found in today’s cell phones, portable media players (PMPs) and other portable applications. The FAN5355, an 800mA/1000mA 3MHz Buck converter, has been designed with a proprietary ultra-fast architecture that consumes very low quiescent current and yet delivers ultra-fast transient response. Typical quiescent current in PFM mode is 37µA and even with this meager standby current, the FAN5355 is able to provide best-in-class transient response, making the application more resilient to unexpected fluctuations in load. In addition, this architecture creates lower ripple during PFM mode, reducing system noise and drastically improving light load efficiency to 85 percent even at loads of only 1mA. For more moderate to heavy loads, careful optimization of the power train contributes to a conversion efficiency of more than 90 percent during PWM mode.
The FAN5355 is equipped with an I2C interface allowing the system to dynamically adjust the digital core's power supply voltage based on the processor workload. Typical cores benefiting from DVS are application processors, graphics processors and DSPs in mobile applications. By tailoring the power supply voltage level to the processing state of the core, energy consumption is reduced leading to longer battery life. In order to maximize the effectiveness of the DVS, the FAN5355’s digitally programmable output voltage has a range of 0.75V to 1.975V and can be adjusted in 12.5mV increments. To accommodate the needs of portable applications, the FAN5355 is available in 3mm x 3mm MLP packaging and 12 bump, 0.5mm pitch WL-CSP packaging.
