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| AIC2951/2951D Low Dropout Linear Regulator n FEATURES l n DESCRIPTION The AIC2951/ 2951D series is the enhanced CMOS version of the LP2951. The superior characteristics of the AIC2951/ 2951D series include zero base current loss, very low dropout voltage, and 1% accuracy output voltage. Typical ground current remains approximately 55A, from no load to maximum loading conditions. Dropout voltage at 100mA output current is significantly lower than its bipolar counterpart: 130mV for the AIC2951-50/2951D-50, 180mV for the AIC295133/ 2951D-33, and 200mV for the AIC2951-30/ 2951D-30. Output current limiting and thermal (R) Low Dropout Voltage of 130mV at 100mA Output Current (AIC2951/2951D-50). Guaranteed 150mA /300mA Output Current. Internal 1.3 P-MOSFET Draws no Base Current. Low Ground Current at 55A. 1% Accuracy Output of 3V/3.3V/5V. Error Flag Warns of Output Dropout. 1A Supply Current in Shutdown Mode. Output Programmable from 1.235V~11V. Fast Transient Response. Needs only 1F for Stability. Current and Thermal Limiting. l l l l l l l l l l n APPLICATIONS l l l Voltage Regulator for Pentium CPUs. Wireless Communication System. Battery Powered Systems. limiting are built in to provide maximal protection to the AIC2951/2951D series from fault conditions. An error flag output, indicating when output voltage drops out of regulation, often due to the falling batteries on the input, can be used for a power-on reset. A logic-controlled shutdown input enables the regulator to be switched on and off. The part may be configured for a fixed output voltage or programmed from 1.235V to 11V with an external pair of resistors. The part comes in 8pin DIP or SO packages. n TYPICAL APPLICATION CIRCUIT VOUT=1.235(1+R1/R2) R3 390 1 2 R4 33 3 SHDN 4 GND TAP ERROR 5 C2 R2 VOUT SENSE VIN FB 8 7 6 C1 + 470 F VIN Q1 D45H2A VOUT R1 + 1000F AIC2951 Pentium Processor Power Supply Analog Integrations Corporation www.analog.com.tw DS-2951-01 Mar 13, 00 TEL: 886-3-5772500 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC FAX: 886-3-5772510 1 AIC2951/2951D Low Dropout Linear Regulator n ORDERING INFORMATION AIC2951 X-XXXX PACKAGE TYPE N: PLASTIC DIP S: SMALL OUTLINE TEMPERATURE RANGE C: 0 C~+70 C OUTPUT VOLTAGE 30 : 3.0V 33 : 3.3V 50 : 5.0V MAX. OUTPUT CURRENT DEFAULT : 150mA D : 300mA ORDER NUMBER AIC2951-30CN AIC2951-33CN AIC2951-50CN AIC2951D-30CN AIC2951D-33CN AIC2951D-50CN (PLASTIC DIP) AIC2951-30CS AIC2951-33CS AIC2951-50CS AIC2951D-30CS AIC2951D-33CS AIC2951D-50CS (PLASTIC SO) PIN CONFIGURATION TOP VIEW VOUT SENSE SHDN GND 1 2 3 4 8 7 6 5 VIN FB TAP ERROR n ABSOLUTE MAXIMUM RATINGS Input Supply Voltage ........................... ... ... ... ... ............................................... -0.3~12V Feedback Input Voltage..................................... ... ... ... ... .................................. -0.3~12V Shutdown Input Voltage ................................... ... ... ... ... .................................. -0.3~12V Error Comparator Output ......................................... ... ... ... .............................. -0.3~12V Operating Junction Temperature Range ................ ... ... ... .......................... -40C~125 C Storage Temperature Range ............................... ... ... ... ............................ -65C~150 C n TEST CIRCUIT VOUT + COUT 10F VOUT SENSE SHDN GND VIN VREF FB TAP 1mA ERROR + CIN 1 F VIN SHUTDOWN AIC2951 2 AIC2951/2951D n ELECTRICAL CHARACTERISTICS (Ta=25C, C erwise specified.) PARAMETER Output Voltage IN=1F, COUT=10F, unless oth- TEST CONDITIONS No Load AIC2951/2951D-50 AIC2951/2951D-33 AIC2951/2951D-30 VIN=5.5~12V VIN=3.6~12V VIN=3.3~12V MIN. 4.950 3.267 2.970 TYP. MAX. 5.0 3.3 3.0 50 5.050 3.333 3.030 150 UNIT V Output Voltage Tempera- (Note 1) ture Coefficiency Line Regulation IL =1mA AIC2951/2951D-50 AIC2951/2951D-33 AIC2951/2951D-30 AIC2951-50 AIC2951D-50 AIC2951-30/ -33 AIC2951D-30/-33 AIC2951-50 AIC2951-30/ -33 AIC2951D-50 AIC2951D-30/ -33 AIC2951/2951D AIC2951-50 AIC2951-33 AIC2951-30 AIC2951D-50 AIC2951D-33 AIC2951D-30 IO=0.1mA~IMAX AIC2951/2951D-50 AIC2951/2951D-33 AIC2951/2951D-30 AIC2951-50 AIC2951-30/ -33 VIN=5.5~12V VIN=3.6~12V VIN=3.3~12V VIN=7V, VIN=7V, VIN=5V, VIN=5V, IL =0.1~150mA IL =0.1~300mA IL =0.1~150mA IL =0.1~300mA VOUT =0V VOUT =0V VOUT =0V VOUT =0V PPM/C 3 3 3 7 7 7 7 220 220 440 440 0.2 200 270 300 400 540 600 55 55 55 1.222 1.222 1.235 1.235 50 10 10 10 15 25 15 25 mV Load Regulation (Note 2) mV Current Limit (Note 3) VIN=7V, VIN=5V, VIN=7V, VIN=5V, MA Dropout Voltage (Note 4) IL =0.1mA IL =150mA IL =150mA IL =150mA IL =300mA IL =300mA IL =300mA VIN=5.5~12V VIN=4~12V VIN=4~12V VIN=5.5~12V VIN=3.6~12V 10 300 370 400 500 640 700 80 80 80 1.248 1.248 150 60 1 mV Ground Current A FB Reference Voltage Reference Voltage Temp. Coef. (Note 1) FB Pin Current Error Pin off Leakage Current Error Pin Pull Low Voltage V PPM/C NA A AIC2951/2951D AIC2951/2951D IOL=1mA AIC2951/2951D-50 AIC2951/2951D-33 VIN=7V VIN=7V 20 VIN=4.5V VIN=2.9V 100 100 300 300 mV 3 AIC2951/2951D AIC2951/2951D-30 VIN=2.7V 100 300 n ELECTRICAL CHARACTERISTICS (CONTINUED) PARAMETER Output Voltage TEST CONDITIONS No Load AIC2951/2951D-50 AIC2951/2951D-33 AIC2951/2951D-30 VIN=5.5~12V VIN=3.6~12V VIN=3.3~12V MIN. 4.950 3.267 2.970 40 TYP. MAX. 5.0 3.3 3.0 60 68 88 2 25 2 5.050 3.333 3.030 UNIT V Error Pin Upper Threshold Voltage Error Pin Lower Threshold Voltage Shutdown Threshold Voltage Shutdown Input Bias Current Shutdown Supply Current Note 1: Note 2: Note 3: Note 4: AIC2951/2951D AIC2951/2951D AIC2951/2951D VIN=7V VIN=7V, VSHDN=2V VIN=7V, VSHDN=2V mV MV V A A 0.5 0.8 10 Guaranteed by design. Regulation is measured at constant junction temperature, using pulse testing with a low ON time. Current limit is measured by pulsing a short time. 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. 4 AIC2951/2951D n TYPICAL PERFORMANCE CHARACTERISTICS Reference Voltage vs Temperature 1.28 60 Ground Current vs. Input Voltage Reference Voltage (V) 1.26 50 1.24 VREF=1.244V VREF=1.235V VREF=1.225V Ground Current (A) 125 40 30 1.22 20 1.2 10 1.18 -50 -25 0 25 50 75 100 0 0 1 2 3 4 5 6 7 8 Temperature(C) Input Voltage (V) Ground Current vs. Temperature 60 600 Dropout Voltage vs Load Current 500 58 Dropout Voltage (mV) Ground Current (A) VOUT=3V 400 56 IL =300mA IL=150mA VOUT =3.3V 300 54 VOUT =5V 200 52 IL=0.1mA 100 50 -50 -25 0 0 Temperature( C) 25 50 75 100 125 0 50 100 150 200 250 300 Load Current (mA) Dropout Voltage vs Temperature 600 500 Short Circuit Current vs. Temperature Dropout Voltage(mV) IL =300mA 400 Short Circuit Current (mA) 500 VOUT =5V AIC2951D 400 300 IL =150mA 200 300 100 AIC2951 IL =0.1mA 0 -50 -25 0 25 50 75 100 125 200 -50 -25 0 Temperature( C) Temperature (C) 25 50 75 100 125 5 AIC2951/2951D n TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED) Line Transient Response 100 Load Transient Response Output Voltage (mV, AC) 100 Output Voltage (mV, AC) 50 COUT=1F VOUT=5V 0 0 -50 C OUT=1F IL=1mA V OUT =5V -100 -200 Input Voltage (V) Load Current (mA) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 8 150 6 0.1 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Time (mS) Time (mS) Load Transient Response Output Voltage (mV, AC) 20 0 -20 Enable Transient Output Voltage (V) 6 COUT =10F V OUT=5V COUT=1F 4 2 -40 -60 C OUT=10 F 0 IL=10mA V IN=8V V OUT=5V Shutdown Voltage (V) Load Current (mA) 150 2 0.1 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Time (mS) Time (mS) FB Pin Bias Current vs. Temperature 40 2.8 Minmum Operating Voltage vs Temperature Minimum Operating Voltage (V) 2.7 FB Pin Current (nA) 30 2.6 2.5 20 2.4 2.3 10 -50 -25 0 25 50 75 100 125 Temperature (C) 2.2 -50 -25 0 Temperature (C) 25 50 75 100 125 6 AIC2951/2951D n BLOCK DIAGRAM FB 7 8 VIN 1 2 SENSE RF1 + VOUT 3 SHDN ERROR AMP RF2 6 TAP 60mV + + 5 ERROR DETECTION COMPARATOR 4 ERROR + 1.235V REFERENCE GND n PIN DESCRIPTIONS PIN 1: VOUT - Output pin. PIN 2: SENSE -Remote sense input, connected to internal resistor divider. PIN 3: SHDN - Shutdown input. PIN 4: GND - Power GND. PIN 8: VIN PIN 5: ERROR - Open drain output of error flag warns. - Center output of internal resistor divider. - Error amplifier positive feedback (see Block Diagram) - Power supply input PIN 6: TAP PIN 7: FB n APPLICATION INFORMATIONS Output Filter Capacitors A 1F (or greater) capacitor is required between the AIC2951/AIC2951D 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 150mA 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 AIC2951/2951D 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 AIC2951/2951D from nearby noise sources can also upset the output. This may especially be a problem when using high value external resisProgramming the Output Voltage tors to set the output voltage. Adding a 100pF capacitor between output and feedback and increasThe AIC2951/2951D series can be set to deliver ing the output capacitor to at least 3.3F will cure any output voltage from 1.235V to 11V by using an this problem. external voltage divider. In addition, internal voltage 7 AIC2951/2951D dividers are provided for 3.0V/3.3V/5.0V output versions. To use the internal voltage divider, connect the SENSE pin to output and the TAP pin to the FB pin. When using an external divider the SENSE and TAP pins are left open, and the divider is installed from the output to ground, with its center connected to the FB pin (see Fig. 1). When using an external voltage divider, resistance can be calculated from the following formula: R1 VOUT = VREF x (1 + ) + IFB x R1 R2 V OUT VIN + C1 R1 1 2 3 4 VOUT SENSE SHDN GND VIN FB TAP 8 7 6 R2 ERROR 5 C3 0.01F + C2 3.3 F R2. Using a 1.2M resistor for R2, the bias current will already cause a 2% shift in output voltage. For better accuracy, choosing R2=100K reduces this error to 0.17% at the price of merely increasing the resistor programming current to 12A. Reducing Output Noise In reference applications it may be advantageous to reduce the AC noise present at the output. One method is to reduce the regulator bandwidth by increasing the size of the output capacitor. Another, noise can be reduced by bypassing the upper r esistor in the feedback divider with a small capacitor, since the capacitor provides a more direct path for AC feedback. The size of this capacitor can be calculated from the formula: CBYPASS 1/(2 N R1N fCORNER ) Where R1 is the upper resistor of the feedback d ivider and fCORNOR is the frequency above which the increased AC feedback is to become active. The reduction of the output noise at high frequency will be proportional to the ratio of the two resistors in the feedback divider, R2/(R1+R2). In order to maintain regulator stability when using a noise-reducing bypass capacitor, it will also be necessary to i n crease the size of the output filter capacitor by the same ratio. SHUTDOWN AIC2951 Fig. 1 Adjustable Regulator Where VREF is the nominal 1.235V reference voltage and IFB is the feedback pin bias current, nominally 20nA. The minimum recommended load current of 1A forces an upper limit of 1.2M on the value of n APPLICATION EXAMPLES Load Transient Response Output Voltage (mV, AC) VOUT=1.235(1+R1/1K) R3 390 1 2 R4 33 SENSE 3 SHDN 4 GND TAP ERROR 5 FB VOUT VIN 8 7 6 C1 + 100 0 -100 1000F 6.3V VIN 5V VOUT=3.3V Q1 D45H2A VOUT R1 * C2 R2 1K Load Current (A) + 1000Fx5 6.3V 5 0 AIC2951 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Fig. 2 Pentium Processor Power Supply (R) Time (mS) 8 AIC2951/2951D n APPLICATION EXAMPLES (CONTINUED) IL=1.235/R LOAD V IN=2.5V-12V VOUT VIN 1 8 VOUT VIN FB TAP ERROR 7 6 5 R + 1F C1 + 1 VOUT C1 1 F 2 SENSE 3 4 SHDN GND VIN 8 FB 7 TAP ERROR VIN=2.5V-12V 2 3 4 SENSE SHDN GND 6 5 AIC2951 AIC2951 Fig. 3 Current Limiter Fig. 4 Precision Sink Current Source n PHYSICAL DIMENSIONS l 8 LEAD PLASTIC SO (unit: mm) D SYMBOL A H E MIN 1.35 0.10 0.33 0.19 4.80 3.80 MAX 1.75 0.25 0.51 0.25 5.00 4.00 1.27(TYP) 6.20 1.27 A1 B C D e A C A1 E e H L 5.80 0.40 B L 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 E1 C A2 A1 L e eB L 2.54 (TYP) eB b e 9 AIC2951/2951D 10 |
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