AIC1579LCS

AIC1579/L Step-Down Switching Regulator Controller FEATURES Operation Voltage up to 15V. Simple Voltage-Mode PWM Control. Fast Transient Response. 2V and 1.3V ± 2% Feedback Voltage Reference Option. Adjustable Current Limit without External Sense Resistors. 200KHz Free-Running Oscillator. Short-Circuit Protection with Low Short Circuit Output Current. DESCRIPTION The AIC1579 is a high-power, high-efficiency voltage-mode switching regulator controller for motherboard VI/O power supply applications. Designed to drive an N-channel MOSFET in a standard buck topology, the AIC1579 features a high voltage CMOS output driver, short-circuit protection, and 8-pin package. An external 4-bit Digital-to-Analog Converter (DAC) can be used along with the AIC1579 to adjust the output voltage from 2.0V to 3.5V in 0.1V increments. Table 1 on the following page specifies the corresponding output voltage for 16 combinations of DAC inputs as in the typical application circuit. The 200KHz switching frequency allows for using small external components while maintaining high conversion efficiency. The 11MHz bandwidth and 6V/µS slew rate of the error amplifier ensures high converter bandwidth and fast transient response. The AIC1579 provides adjustable overcurrent and short-circuit protections by sensing the output current across the on resistance of the external N-channel MOSFET rather than an external low value sense resistor. The AIC1579L provides lower reference voltage (1.30V) than the default (2.00V, AIC1579) for lower VOUT requirement. APPLICATIONS Power Supply for Motherboard VGTL (1.5V Output) Power Supply for Motherboard VI/O. High-Power 5V to 3.xV DC/DC Regulators. Low-Voltage Distributed Power Supplies. Analog Integrations Corporation DS-1579-01 Nov 9, 00 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC TEL: 886-3-5772500 FAX: 886-3-5772510 www.analog.com.tw 1 AIC1579/L ORDERING INFORMATION AIC1579 XXX PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE TEMPERATURE RANGE C=0°C~+70°C REFERENCE VOLTAGE DEFAULT: 2.00V L: 1.30V ORDER NUMBER AIC1579CN AIC1579LCN (PLASTIC DIP) AIC1579CS AIC1579LCS (PLASTIC SO) PIN CONFIGURATION TOP VIEW OCSET 1 SS 2 COMP 3 FB* 4 *AIC1579: 2.00V AIC1579L: 1.30V 8 VCC 7 UGATE 6 PHASE 5 GND TYPICAL APPLICATION CIRCUIT C2 1000pF R1 C5 0.1µF 2.2K 1% OCSET SS VCC UGATE *C1 MUST BE VERY CLOSE TO VCC PIN 10Ω R8 C1* 1µF M1 RFP45N03L + C3 1000µFx2 3.3V/10A VOUT L2 7µH + C4 1000µ F x 6 12V L1 1µH 5V C6 33P C7 COMP PHASE FB GND AIC1579 R2 90.9K 1% 1000pF R4 VID0 VID1 VID2 VID3 60.4K 1% R5 30.1K 1% R6 15.0K 1% R7 7.5K 1% R3 3.01K 1% D1 BYV118 Switching Regulator for Pentium VCORE Supply 2 AIC1579/L Table 1. Output Voltage Program VID3 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 VID2 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 VID1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 VID0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 VOUT 2.00V 2.10V 2.20V 2.30V 2.40V 2.50V 2.60V 2.70V 2.80V 2.90V 3.00V 3.10V 3.20V 3.30V 3.40V 3.50V ABSOLUTE MAXIMUM RATINGS Supply Voltage, VCC ....…...………............................…………......................................... 15V Input, Output, or I/O Voltage ...............………………....……......... GND - 0.3V to VCC+0.3V ESD Classification .............................………….....……..............……......................... Class 2 Recommended Operating Conditions Supply Voltage, VCC ....…......................………….......……….................................. 12V ±10% Ambient Temperature Range .…................................………….……….................. 0°C~70°C Junction Temperature Range ....…............……….........…..……......................... 0°C~ 100°C Thermal Information Thermal Resistance, θJA (Typical, Note 1) SOIC Package ...............................………………………..……………........…. 100°C/W SOIC Package (with 3 in2 of Copper) ……………………………………......….. 90°C/W Maximum Junction Temperature (Plastic Package) ……….……..………................... 150°C Maximum Storage Temperature Range …………..…………......…….…......... –65°C~150°C Maximum Lead Temperature (Soldering 10 Sec) …………………...……......…......... 300°C Note 1: θJA is measured with the component mounted on an evaluation PC board in free air. TEST CIRCUIT Refer to TYPICAL APPLICATION CIRCUIT. 3 AIC1579/L ELECTRICAL CHARACTERISTICS specified.) PARAMETER VCC Supply Current Nominal Supply Power-On Reset VCC Threshold Oscillator Frequency Max. Duty Cycle Internal Reference Voltage Reference Voltage Error Amplifier DC Gain Gain-Bandwidth Product Slew Rate Gate Driver Upper Gate Source Upper Gate Sink Protection OCSET Current Source SS Current VOCSET =4.5VDC IOCSET ISS 170 200 10 230 µA µA RUGATE RUGATE 8 5.5 12 10 Ω Ω GBW SR 76 11 6 dB MHz V/µS AIC1579 AIC1579L 1.96 1.27 2.00 1.30 2.04 1.33 V 160 200 240 100 KHz % VOCSET=4.5V 10.4 V UGATE Open IVCC 2.3 mA TEST CONDITIONS (VCC= 12V, Ta=25°C, unless otherwise SYMBOL MIN. TYP. M AX. UNIT TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs. Load Current 100 90 OCSET Current vs. Temperature 200 Vo=3.5V Vo=2.0V Vo=1.3V Efficiency (%) 80 70 60 50 40 Clset (µA) 198 196 Tc=134ppm/ C@ 0~100°C 194 192 30 1 2 3 4 IOUT (A) 5 6 7 8 9 10 11 -40 -20 0 20 Temperature (°C) 40 60 80 100 120 140 160 4 AIC1579/L TYPICAL PERFORMANCE CHARACTERISTICS(Continued) SS Current vs. Temperature 9.9 Over-Current Operation 9.8 Soft Start (µA) 9.7 9.6 Tc = 306 ppm/°C @ 0~100°C 9.5 9.4 9.3-40 -20 0 20 40 60 80 100 120 140 160 Temperature (°C) Soft Start Initiates Output Transient Response 5 AIC1579/L BLOCK DIAGRAM SS PHASE OCSET + 10µA Over Current 200µA Soft Start 4V PWM Comparator REF. + Error AMP Oscilator Gate Control Power-ON Reset VCC UGATE FB COMP GND PIN DESCRIPTIONS PIN 1: OCSET - Current limit sense pin. Connect a resistor ROCSET from this pin to the drain of the external MOSFET. ROCSET, an internal 200µA current source (IOCSET), and the external MOSFET onresistance (RDS(ON)) jointly set the overcurrent trip point according to the following equation: comparator. A RC network is connected to FB pin to compensate the voltage-control feedback loop of the converter. PIN 4: FB - The error amplifier inverting input pin. The FB pin and COMP pin are used to compensate the voltage-control feedback loop. Ground pin. Overcurrent detection pin. Connect the PHASE pin to source of the external NMOSFET. This pin detects the voltage drop across the MOSFET RDS(ON) for overcurrent protection. PIN 5: GNDPIN 6: PHASE- IPEAK IOCSET × ROCSET = RDS(ON) If FB pin voltage is sensed to be below 50% of the internal voltage reference VDAC, the overcurrent comparator cycles the soft-start function. PIN 2: SS - Soft start pin. Connect a capacitor from this pin to ground. An internal 10µA current source provides soft start function for the converter. PIN 7: UGATE- External MOSFET gate drive pin. Connect this pin to gate of the external MOSFET. PIN 8: VCC -The chip power supply pin. Recommended supply voltage is 12V. PIN 3: COMP - External compensation pin. This pin is connected to error amplifier output and PWM 6 AIC1579/L APPLICATION CIRCUIT C2 1000pF R1 C5 0.01µF 2.2K 1% OCSET SS COMP FB VCC UGATE PHASE GND *C1 MUST BE VERY CLOSE TO VCC PIN 10Ω R8 C1* 1µF M1 RFP45N03L + C3 1000µFX2 L2 D1 R3 BYV118 7µH + C4 1000µF x 6 1.5V/10A VOUT 12V L1 1µH 5V C6 33P R2 90.9K 1% AIC1579L C7 1000pF 1% 13K R4 1% 2K *VOUT=1.3V x (1+ R3/R4) PHYSICAL DIMENSIONS 8 LEAD PLASTIC SO (unit: mm) D SYMBOL A H E MIN 1.35 0.10 0.33 0.19 4.80 3.80 5.80 0.40 MAX 1.75 0.25 0.51 0.25 5.00 4.00 6.20 1.27 A1 B C D E e A C A1 e H L L 1.27(TYP) B 7 AIC1579/L 8 LEAD PLASTIC DIP (unit: mm) D SYMBOL A1 E1 MIN 0.381 2.92 0.35 0.20 9.01 7.62 6.09 — 2.92 MAX — 4.96 0.56 0.36 10.16 8.26 7.12 10.92 3.81 A2 b C E D E C A2 A1 L E1 e eB L 2.54 (TYP) eB b e 8