FAN5235QSCX

www.fairchildsemi.com FAN5235 System Electronics Regulator for Mobile PCs Features 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. 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 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 2 3.3 ALW 5V-ALWAYS 3 CPUMP3.3 5V-ALWAYS CPUMP5 24 HSD5 23 5V @ 5A + SW5 22 4 HSD3.3 ISEN5 21 5 SW3.3 LSD5 20 6 5V-ALW GND5 19 7 LSD3.3 VFB5 18 8 GND3.3 SDN5 17 9 ISEN3.3 SW12 16 10 VFB3.3 VFB12 15 3.3V @ 5A + 5V-ALWAYS@ 50mA SDN3.3 11 SDN3.3 SGND 14 PGOOD 12 PGOOD SDWN 13 SDN5 12V @ 120mA + VFB12 SDWN REV. 1.3.3 1/3/02 FAN5235 Pin Assignments Top View VIN 3.3V-ALWAYS CPUMP3.3 HSD3.3 SW3.3 5V-ALWAYS LSD3.3 GND3.3 ISEN3.3 VFB3.3 SDN3.3 PGOOD 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 CPUMP5 HSD5 SW5 ISEN5 LSD5 GND5 VFB5 SDN5 SW12 VFB12 SGND SDWN Pin Description Pin Name 2 Pin Number Pin Function Description VIN 1 Input power. 3.3V-ALWAYS 2 3.3V Always on linear regulator. Load current on pins 2 and 6 must not exceed 50mA total. CPUMP3.3 3 Charge Pump 3.3V. High side Gate drive voltage for 3.3V. This pin is to be connected to SW3.3 through a 100nF cap. and to 5V-ALWAYS through a diode HSD3.3 4 High-side gate driver for 3.3V. Connect this pin directly to the gate of an N-channel MOSFET. The trace from this pin to the MOSFET gate should be < 1". SW3.3 5 High side FET Source and Low Side FET Drain Switching Node. Switching node for 3.3V. 5V-ALWAYS 6 5V Always on linear regulator output. The sum of the load currents on pins 2 and 6 must not exceed 50mA total. LSD3.3 7 Low-side gate driver for 3.3V. Connect this pin directly to the gate of an N-channel MOSFET. The trace from this pin to the MOSFET gate should be < 1". GND3.3 8 Ground for 3.3V MOSFET. ISEN3.3 9 Current sense for 3.3V. This pin should be connected to the Drain of the bottom Mosfet with an appropriate resistor and an RC filter. See Application Section. VFB3.3 10 Voltage feedback for 3.3V. SDN3.3 11 Soft Start and ON/OFF for 3.3V. OFF=GND. ON=open with SDWN=High. Use open collector device for control. PGOOD 12 Power Good Flag. An open collector output that will be logic low if any output voltage is not above 89% of the nominal output voltage. SDWN 13 Master Shutdown. Shutdown for all power. Off when low. When high 5V/3.3V-ALWAYS are ON while 5V/3.3V-Main are ready to turn on if SDN5, SDN3.3 go open. SGND 14 Signal ground. VFB12 15 Voltage feedback for 12V. SW12 16 FET driver for 12V Boost. SDN5 17 Enable/Soft Start for 5V and 12V. Soft start and ON/OFF for 5V & 12V. OFF=Grounded. ON=open with SDWN=High. VFB5 18 Voltage feedback for 5V. GND5 19 Ground for 5V MOSFET. LSD5 20 Low side FET driver for 5V. Connect this pin directly to the gate of an N-channel MOSFET. The trace from this pin to the MOSFET gate should be < 1". REV. 1.3.3 1/3/02 FAN5235 Pin Description (Continued) Pin Name Pin Number Pin Function Description ISEN5 21 Current Sense for 5V. This pin should be connected to the drain of the bottom Mosfet using appropriate resistor and RC filter. See Application Section. SW5 22 High Side Driver Source and Low Side Driver Drain Switching Node. Switching node for 5V. HSD5 23 High side FET driver for 5V. Connect this pin directly to the gate of an N-channel MOSFET. The trace from this pin to the MOSFET gate should be < 1". CPUMP5 24 Charge Pump 5V. High side Gate drive voltage for 5V. High side Gate drive voltage for 5V. This pin is to be connected to SW5 through a 100nF cap. and to 5V-ALWAYS through a diode. Absolute Maximum Ratings1 Max. Units VIN Parameter Conditions Min. -0.3 Typ. 27 V SW, ISEN Pins,SDWN Pin -0.3 27 V CPUMP, HSD Pins -0.3 33 V SDN, VFB, V_always pins -0.3 6.5 V CPUMP to SW pins, and all other pins -0.3 6.5 V The sum of the load currents on pins 2 and 6 must not exceed 60mA total Note: 1. Stresses beyond "Absolute Maximum Ratings" may cause permanent device damage. Continuous exposure to absolute maximum rating conditions may affect device reliability. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specification is not implied. Recommended Operating Conditions Input Voltage, VIN +5.4V to 24V Ambient Temperature, TA -20°C to 85°C Thermal Information Thermal Resistance, θJA Thermal Resistance, θJC 88°C/W QSOP 28.5°C/W TSSOP 16°C/W Maximum Junction Temperature Storage Temperature Range Maximum Lead Temperature, Soldering 10 Sec REV. 1.3.3 1/3/02 150°C -65°C to 150°C 300°C 3 FAN5235 ELECTRICAL SPECIFICATIONS Operating Conditions Recommended Operating Conditions Unless Noted Refers to Block Diagrams Parameter Conditions Min. VIN Input Supply Voltage (DC loading only) Note 1 5.4 Input Quiescent Current H/LSD Open Typ. Max. Units 24 V 1.4 3 mA Stand-by 300 400 µA Shut-down