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| AIC1741 LOW DROPOUT ADJUSTABLE REGULATOR SPEC NO: DS-1741-00 FEATURES 1% Accuracy 1.235V Voltage Reference. Fast Transient Response. Low Ground Current at 55A. Wide Output Current Range, 10A~80mA. Output Programmable from 1.235V~11V. Low Temperature Coefficiency. Error Flag Warns of Output Dropout. DESCRIPTION The AIC1741 is a low power precision adjustable regulator with 80mA output capability. The device can be used as a secondary regular to provide feedback in a switching power supply. The AIC1741 circuitry includes an internal wide band amplifier, a precision bandgap reference, and a PMOS output transistor. The feedback input can be connected to an external resistor divider to program the sensed output voltage. The VOUT pin provides loop frequency compensation when used as a part of a larger servo system. Although the device works as a stand-alone regulator, it can also drive an NPN power transistor to construct a high current low dropout regulator, with only very minor current loss to ground. APPLICATIONS Voltage Regulator for Pentium(R) CPUs. Wireless Communication System. 5V to 3.3V Regulator for VGA Cards. Battery Powered Systems. TYPICAL APPLICATION CIRCUIT VIN 5V Q1 TIP31C VOUT 3.3V/3 A C3 10F + R3 2K R1 390 + C2 33F 1 VOUT 2 NC 3 GND 4 VIN 8 + FB 7 FLAG 6 NC 5 C1 10F NC AIC1741 R2 1.2K 5V to 3.3V Regulator for VGA Cards. ORDERING INFORMATION AIC1741 XX PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE TEMPERATURE RANGE C: 0C~+70C ORDER NUMBER AIC1741CN (PLASTIC DIP) PIN CONFIGURATION TOP VIEW VOUT NC 1 2 3 4 8 7 6 5 VIN FB FLAG NC AIC1741CS (PLASTIC SO) (R) GND NC Pentium ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. is a registered trademark of Intel Corporation www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 1 AIC1741 LOW DROPOUT ADJUSTABLE REGULATOR SPEC NO: DS-1741-00 ABSOLUTE MAXIMUM RATINGS Input Supply Voltage Feedback Input Voltage Shutdown Input Voltage Error Comparator Output ..................................................................................... -0.3~12V .................................................................................. -0.3~12V ................................................................................. -0.3~12V ................................................................................ -0.3~12V ................................................... -40C~125C Operating Junction Temperature Range Storage Temperature Range .................................................................... -65C~150C TEST CIRCUIT 8 VIN + CIN 1F 1mA 7 VIN FB VOUT NC 1 2 VOUT 3.3V COUT 10F R1 2K R2 1.2K 6 FLAG 5 NC AIC1741 GND 3 NC 4 ELECTRICAL CHARACTERISTICS (Ta=25C, CIN=1F, COUT=10F, unless otherwise specified. Test conditions are referred to TEST CIRCUIT.) PARAMETER Output Voltage Output Voltage Temperature Coefficiency Line Regulation Load Regulation (Note 2) TEST CONDITIONS VIN=3.6~12V, No Load, VOUT=3.3V (Note 1) VIN=3.6~12V, IL=1mA, VOUT=3.3V VIN=7V, IL=0.1~80mA, VOUT=3.3V IL=0.1mA IL=80mA, VOUT=3.3V VIN=4~12V, IO=0.1mA~IMAX VIN=7V IOL=1mA, VIN=2.9V MIN. 3.267 TYP. 3.3 50 3 4 0.2 200 55 MAX. 3.333 150 10 10 10 300 80 1 UNIT V PPM/C mV mV mV A A Dropout Voltage (Note 3) Ground Current Flag Pin Off Leakage Current Flag Pin Pull Low Voltage 100 300 mV Flag Pin Upper Threshold 40 60 mV Voltage Flag Pin Lower Threshold 68 88 mV Voltage Note 1: Guaranteed by design. Note 2: Regulation is measured at constant junction temperature, using pulse testing with a low ON time. Note 3: Dropout voltage is defined as the input to output differential at which the output voltage drops 100mV below the value measured with a 1V differential. ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 2 AIC1741 LOW DROPOUT ADJUSTABLE REGULATOR SPEC NO: DS-1741-00 TYPICAL PERFORMANCE CHARACTERISTICS Reference Voltage vs. Temperature 1.28 60 Ground Current vs. Input Voltage 1.26 50 Reference Voltage (V) VREF=1.244V 1.24 Ground Current (A) 125 40 VREF=1.225V 1.22 30 VREF=1.225V 1.2 20 10 1.18 -50 -25 0 25 50 75 100 0 0 2 4 6 8 Temperature (C) Input Voltage (V) 10 12 Ground Current vs. Temperature 60 200 Dropout Voltage vs. Load Current 58 VOUT=3.3V Dropout Voltage (mV) IL=80mA 150 Ground Current (A) 56 100 54 IL=0.1mA 52 50 50 -50 -25 0 25 50 75 100 125 0 0 20 40 60 80 100 Temperature(C) Load Current (mA) Dropout Voltage vs Temperature 300 40 Bias Current vs. Temperature 250 VOUT=3.3V IL=80mA Bias Current (nA) IL=0.1mA 30 Dropout Voltage(mV) 200 150 100 20 50 0 -50 -25 0 25 50 75 100 125 10 -50 -25 0 25 50 75 100 125 Temperature(C) Temperature (C) ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 3 AIC1741 LOW DROPOUT ADJUSTABLE REGULATOR SPEC NO: DS-1741-00 TYPICAL PERFORMANCE CHARACTERISTICS Minimum Operating Voltage vs Temperature 2.8 (CONTINUED) Minimum Operating Voltage (V) 2.7 2.6 2.5 2.4 2.3 2.2 -50 -25 0 Temperature (C) 25 50 75 100 125 BLOCK DIAGRAM 8 VIN 7 FB + 1 VOUT 66mV + 6 FLAG 3 GND 1.235V, Reference PIN DESCRIPTIONS PIN 1: VOUT - Output pin. PIN 2: NC PIN 3: GND PIN 4: NC PIN 5: NC - Power GND. PIN 6: FLAG - Open drain output of error flag warns. PIN 7: FB PIN 8: VIN - Error amplifier positive feedback (see Block Diagram) - Power supply input. ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 4 AIC1741 LOW DROPOUT ADJUSTABLE REGULATOR SPEC NO: DS-1741-00 APPLICATION INFORMATIONS The AIC1741 has two major applications, one as a low dropout linear regulator and another an error amplifier for a switching power supply to provide precision feedback control. nearby noise sources can also upset the output. This may especially be a problem when using high value external resistors to set the output voltage. Adding a 100pF capacitor between output and feedback and increasing the output capacitor to at least 3.3F will cure this problem. The AIC1741 can drive low cost NPN bipolar transistor to deliver more output current. Typical application circuit is an example of 5V to 3.3V linear regulator for VGA cards power supply. A 390 resistor and 1F capacitor are needed between VOUT pin and ground for stability. The minimum dropout voltage between input to output is VBEQ1+VDS of AIC1741 output PMOSFET, typical 1V @ 3A output current. Use as a Linear Regulator When AIC1741 is connected as a low dropout linear regulator, two external divider resistors are needed to set the output voltage (see Test Circuit). The output voltage can be calculated from the following formula: VOUT=VREF(1+R1/R2)+IFBR1 where VREF is the nominal 1.235V reference voltage and IFB is the feedback pin bias current, nominally -20nA. For better accuracy, the recommended maximum value of R2 is 100K. A 1F (or greater) capacitor is required between the AIC1741 output and ground for stability. Without this capacitor the part will oscillate. Even though most types of capacitor may work, if Aluminum electrolytic type is used, the equivalent series resistance (ESR) should be held to 5. or less. Many Aluminum electrolytics have electrolytes that freeze at about -30C, so solid tantalums are recommended for operation below -25C. The value of this capacitor may be increased without limit. The output capacitance required for stability varies with output voltage (smaller for higher output voltage) and output current (smaller for lower output currents). At the worst-case situation of a 80mA load at 1.235V output (output shorted to FB pin) a 3.3 F or greater capacitor should be used. A 0.1F capacitor should be placed from the AIC1741 input to ground if the lead inductance between the input and power source exceeds 500nH (approximately 10 inches of trace). Noise injection into the feedback terminal of the AIC1741 from ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. Use as an Error Amplifier Fig. 1 shows a popular application for the AIC1741 in switching power supply. The output voltage is sensed between FB pin and GND pin of the AIC1741 through the divider resistor. The VIN pin servos to control the duty cycle of the pulse width modulator to stabilize the output voltage at the set voltage. The FB pin and VIN pin are in same phase while the FB pin and VOUT pin are in opposite phases. Connecting a capacitor from VOUT pin to FB pin provides frequency compensation for the control loop. The AIC1741 provides output voltage remote sensing to improve precision and regulation specifications of the output of the switching power supply. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 5 AIC1741 LOW DROPOUT ADJUSTABLE REGULATOR SPEC NO: DS-1741-00 APPLICATION EXAMPLES C3 D2 1N4148 SC BST 12V + C1 47F SE R1 1K 0.1F 1N4148 2N2907A D3 Q2 MTD20N03DH Q1 + VIN 1000F/6.3Vx2 C6 L1 7.5F 0.022F R2 24K C2 220pF R8 10K C11, C12: Ceramic Capacitor L1: Iron Powder Core VOUT= (1+R10/1K)x1.235V C4 ZD1 5V VOUT : 2.5V~3.5V/10A + 1000F C4 C10 C11 0.1F 0.1F 1000F/6.3V x2 x2 x5 + C13 P5 MICROPROCESSOR CPU BYV118 VIN AIC1562 TC VCC GND FB D1 5.1V FB R2* R10 R7 C5 470 0.1F 1K R3 1K GND VOUT AIC1741 Fig. 1 CPU Power Supply for P5 Mother Board PHYSICAL DIMENSIONS 8 LEAD PLASTIC DIP 9.30.3 8 LEAD PLASTIC SO 4.800.20 6.20.2 3.80.2 8.00.5 3.30.1 0.60.3 3.20.3 2.50.1 10max 8.51.0 0.50.1 2.540.10 1.270.10 0.250.10 0.015X45 1.50.2 0.2 0.1 0.450.10 6.00.2 8 max. UNIT: mm ANALOG INTEGRATIONS CORPORATION 4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C. www.analog.com.tw TEL: (8863)577-2500 FAX:(8863)577-2510 6 |
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