AIC1579/L Step-Down Switching Regulator Controller FEATURES DESCRIPTION Operation Voltage up to 15V. The AIC1579 is a high-power, high-efficiency Simple Voltage-Mode PWM Control. voltage-mode switching regulator controller for Fast Transient Response. motherboard VI/O power supply applications. 2V and 1.3V ± 2% Feedback Voltage Reference Designed to drive an N-channel MOSFET in a Option. standard buck topology, the AIC1579 features a Adjustable Current Limit without External Sense high voltage CMOS output driver, short-circuit Resistors. protection, and 8-pin package. 200KHz Free-Running Oscillator. Short-Circuit Protection with Low Short Circuit An external 4-bit Digital-to-Analog Converter Output Current. (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 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. 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. Analog Integrations Corporation 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC DS-1579-01 TEL: 886-3-5772500 Nov 9, 00 FAX: 886-3-5772510 www.analog.com.tw 1 AIC1579/L ORDERING INFORMATION AIC1579 XXX AIC1579CN AIC1579LCN (PLASTIC DIP) TEMPERATURE RANGE C=0°C~+70°C TOP VIEW 8 VCC OCSET 1 AIC1579CS AIC1579LCS (PLASTIC SO) REFERENCE VOLTAGE DEFAULT: 2.00V L: 1.30V PIN CONFIGURATION ORDER NUMBER PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE SS 2 7 UGATE COMP 3 6 PHASE FB* 4 5 GND *AIC1579: 2.00V AIC1579L: 1.30V TYPICAL APPLICATION CIRCUIT C2 *C1 MUST BE VERY CLOSE TO VCC PIN 10Ω R8 1000pF R1 2.2K 1% C5 OCSET 0.1µF SS R2 33P VCC 5V L1 1µH M1 UGATE RFP45N03L + COMP PHASE FB GND C6 12V C1* 1µF C3 1000µFx2 3.3V/10A VOUT AIC1579 C7 90.9K 1% 1000pF D1 L2 7µH + C4 1000µ F x 6 BYV118 R4 VID0 60.4K 1% R5 VID1 30.1K 1% R6 VID2 15.0K 1% R7 VID3 7.5K 1% R3 3.01K 1% Switching Regulator for Pentium VCORE Supply 2 AIC1579/L Table 1. Output Voltage Program VID3 VID2 VID1 VID0 VOUT 1 1 1 1 2.00V 1 1 1 0 2.10V 1 1 0 1 2.20V 1 1 0 0 2.30V 1 0 1 1 2.40V 1 0 1 0 2.50V 1 0 0 1 2.60V 1 0 0 0 2.70V 0 1 1 1 2.80V 0 1 1 0 2.90V 0 1 0 1 3.00V 0 1 0 0 3.10V 0 0 1 1 3.20V 0 0 1 0 3.30V 0 0 0 1 3.40V 0 0 0 0 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 TEST CONDITIONS (VCC= 12V, Ta=25°°C, unless otherwise SYMBOL MIN. TYP. MAX. UNIT VCC Supply Current Nominal Supply UGATE Open IVCC 2.3 mA Power-On Reset VCC Threshold VOCSET=4.5V 10.4 V 240 KHz 100 % 2.04 1.33 V Oscillator Frequency 160 200 Max. Duty Cycle Internal Reference Voltage Reference Voltage AIC1579 AIC1579L 1.96 1.27 2.00 1.30 Error Amplifier DC Gain 76 dB GBW 11 MHz SR 6 V/µS Upper Gate Source RUGATE 8 12 Ω Upper Gate Sink RUGATE 5.5 10 Ω 200 230 µA Gain-Bandwidth Product Slew Rate Gate Driver Protection OCSET Current Source VOCSET =4.5VDC IOCSET SS Current 170 ISS µA 10 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs. Load Current OCSET Current vs. Temperature 100 Vo=3.5V 80 200 Vo=2.0V Clset (µA) Efficiency (%) 90 70 Vo=1.3V 60 50 198 Tc=134ppm/ C@ 0~100°C 196 194 40 192 30 1 2 3 4 5 6 IOUT (A) 7 8 9 10 11 -40 -20 0 20 40 60 80 100 Temperature (°C) 120 140 160 4 AIC1579/L TYPICAL PERFORMANCE CHARACTERISTICS(Continued) SS Current vs. Temperature Over-Current Operation 9.9 Soft Start (µA) 9.8 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 Over Current 10µA 200µA Power-ON Reset Soft Start VCC 4V PWM Comparator REF. + Error AMP FB Gate Control - UGATE GND Oscilator COMP 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: IPEAK IOCSET × ROCSET = RDS(ON) comparator. A RC network is connected to FB pin to compensate the voltage-control feedback loop of the converter. PIN 4: FB PIN 5: GND- Ground pin. PIN 6: PHASE- 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. 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 3: COMP - External compensation pin. This pin is connected to error amplifier output and PWM - The error amplifier inverting input pin. The FB pin and COMP pin are used to compensate the voltage-control feedback loop. 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. 6 AIC1579/L APPLICATION CIRCUIT *C1 MUST BE VERY CLOSE TO VCC PIN C2 10Ω R8 1000pF R1 2.2K 1% C5 VCC OCSET 0.01µF C6 33P R2 90.9K 1% 12V C1* 1µF SS UGATE COMP FB PHASE 5V L1 1µH M1 RFP45N03L GND + C3 1000µFX2 AIC1579L 1.5V/10A VOUT L2 C7 7µH D1 1000pF R3 1% 13K R4 + C4 1000µF x 6 BYV118 1% 2K *VOUT=1.3V x (1+ R3/R4) PHYSICAL DIMENSIONS 8 LEAD PLASTIC SO (unit: mm) D H E e C B SYMBOL MIN MAX A 1.35 1.75 A1 0.10 0.25 B 0.33 0.51 C 0.19 0.25 D 4.80 5.00 E 3.80 4.00 e A A1 1.27(TYP) H 5.80 6.20 L 0.40 1.27 L 7 AIC1579/L 8 LEAD PLASTIC DIP (unit: mm) D E1 E A2 A1 C L eB b e SYMBOL MIN MAX A1 0.381 — A2 2.92 4.96 b 0.35 0.56 C 0.20 0.36 D 9.01 10.16 E 7.62 8.26 E1 6.09 7.12 e 2.54 (TYP) eB — 10.92 L 2.92 3.81 8