FAN5235

www.fairchildsemi.com FAN5235 System Electronics Regulator for Mobile PCs Features Synchronous rectification ±1% precision internal reference >90% efficiency Input and output voltage feedback 5.4V to 24V input voltage range Internally set 300kHz ±15% oscillator 5V and 3.3V Main outputs switch out of phase 5V-ALWAYS and 3.3V-ALWAYS outputs Adjustable boost converter for 12V Boost converter slaved to 5V Main Input UVLO Outputs OVP of Buck Converters Precision current limit option for 5V, 3.3V Main Power Good Voltage Monitor Description The FAN5235 is a high efficiency and high precision DC/DC controller for notebook converters. Utilization of both input and output voltage feedback in a current-mode control allows for fast and stable loop response over a wide range of input and output voltage variations. The two main regulators switch out of phase to minimize input ripple current. Current sense based on MOSFET Rdson gives maximum efficiency, while also permitting use of a sense resistor for high accuracy. An externally adjustable boost converter can be set to generate 12V. The FAN5235 is available in a 24-pin QSOP package, and in a 24-pin TSSOP package. Applications Notebook PCs and PDAs Hand-held portable instruments Typical Application Vin = 5.4-24V FAN5235 1 VIN 3.3V-ALWAYS@50mA 5V-ALWAYS 2 3.3 ALW 3 CPUMP3.3 4 HSD3.3 3.3V @ 5A + 5 SW3.3 5V-ALWAYS@ 50mA 6 5V-ALW 7 LSD3.3 8 GND3.3 9 ISEN3.3 10 VFB3.3 SDN3.3 PGOOD 11 SDN3.3 12 PGOOD LSD5 20 GND...