AIC1401 PWM Step-Down Switching Controller with Shutdown n FEATURES l l l l l l l l n DESCRIPTION Operation Voltage up to 15V Voltage-Mode Operation The AIC1401 is a high efficiency, PWM step- Fast Transient Response Built In Accurate 1.3V Voltage Reference Adjustable Over Current Protection using RDS(ON) No External Current Sense Resistor Required Low Shutdown Current suitable for IA, Notebook, LCD PC and LCD 200KHz Free-Running Oscillator Built in Soft Start. buck topology. down, voltage-mode, switching controller. It is n APPLICATIONS l l l l l monitor main power applications. The built-in high voltage CMOS driver drives an external N-channel MOSFET for replacing the higher cost P-channel MOSFET in a standard The 200KHz switching frequency allows using Notebook PC Advanced PC Mboards Information PCs smaller external components while maintaining Servers and Workstations PC Add-On Cards amplifier high conversion efficiency. The 11MHz bandwidth and 6V/us slew rate of the error ensures the higher converter bandwidth and the fast transient response. The AIC1401 also features over current protection. It provides adjustable over current trigger point and short-circuit protections by sensing the output current across the on resistance of the external N-channel MOSFET rather then an expensive external low value sense resistor. n ORDERING INFORMATION AIC1401-XX ORDER NUMBER PACKAGE TYPE S: SMALL OUTLINE AIC1401CS (SOP8) TEMPERATURE RANGE C: 0°C ~+70°C PIN CONFIGURATION TOP VIEW OCSET 1 8 VCC /SHDN 2 7 UG COMP 3 6 LX FB 4 Analog Integrations Corporation 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC DS-1401-00 May 24, 01 TEL: 886-3-5772500 FAX: 886-3-5772510 5 GND www.analog.com.tw 1 AIC1401 n TYPICAL APPLICATION CIRCUIT C2 1000P R1 R5 10 12V *C1 1 µF 2.2K *C1 must be very close to VCC PIN OCSET C5 R2 90.9K COMP FB 33P C6 M1 UG LX 5V 1.5µH + VCC /SHDN L1 C3 470µF IR3303 GND R6 L2 5K 7µH AIC1401 D1 SRA1620 1000P R4 R3 13K 2K VOUT 1.5V/5A + C4 330 µFX3 DC/DC Converter n 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 in 2 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. n TEST CIRCUIT Refer to TYPICAL APPLICATION CIRCUIT. 2 AIC1401 n ELECTRICAL CHARACTERISTICS (VCC= 12V, Ta=25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS SYMBOL MIN. TYP. MAX. UNIT VCC Supply Current Nominal Supply UGATE Open IVCC 2 mA 9.5 V Frequency 200 KHz Duty Cycle 88 % Power-On Reset VCC Threshold VOCSET=4.5V Oscillator Internal Reference Voltage 1.27 Reference Voltage 1.30 1.33 V Error Amplifier DC Gain 76 dB GBW 11 MHz SR 6 V/µS Upper Gate Source RUGATE 7 Ω Upper Gate Sink RUGATE 5 Ω IOCSET 200 µA ISS 10 µA Gain-Bandwidth Product Slew Rate Gate Driver Protection OCSET Current Source SS Current VOCSET =4.5VDC Shutdown Shutdown Low Input VIN L Shutdown High Input VIN H Shutdown Mode Current 0.35 2 V V 1 µA 3 AIC1401 n 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) If FB pin voltage is sensed to be below 50% of the internal voltage reference, the overcurrent comparator cycles the soft-start function. PIN 2: /SHDN - Shutdown pin. Connect this pin to ground for shutdown. PIN 3: COMP - External compensation pin. This pin is connected to error amplifier output and PWM n 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. PIN 5: GND - Ground pin. PIN 6: LX - Overcurrent detection pin. Connect the LX pin to source of the external N-MOSFET. This pin detects the voltage drop across the MOSFET RDS(ON) for overcurrent protection. PIN 7: UG - 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. APPLICATION CIRCUIT Refer to TYPICAL APPLICATION CIRCUIT 4 AIC1401 ■ PHYSICAL DIMENSIONS 8 LEAD PLASTIC SO (unit: mm) D H E e 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 1.27(TYP) A C A1 l B H 5.80 6.20 L 0.40 1.27 L 5