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Low Power, Rail-to-Rail Output Precision JFET Amplifier AD8641 FEATURES Low supply current: 250 A max Very low input bias current: 1 pA max Low offset voltage: 750 V max Single-supply operation: 5 V to 26 V Dual-supply operation: 2.5 V to 13 V Rail-to-rail output Unity gain stable No phase reversal SC70 package OUT 1 5 VCC AD8641 VEE 2 +IN 3 4 -IN Figure 1. 5-Lead SC70 (KS-5) NC 1 -IN 2 8 NC VCC OUT 05072-102 AD8641 TOP VIEW (Not to Scale) 7 6 5 APPLICATIONS Line-/battery-powered instruments Photodiode amplifiers Precision current sensing Medical instrumentation Industrial controls Precision filters Portable audio ATE +IN 3 VEE 4 NC NC = NO CONNECT Figure 2. 8-Lead SOIC (R-8) GENERAL DESCRIPTION The AD8641 is a low power, precision JFET input amplifier featuring extremely low input bias current and rail-to-rail output. The ability to swing nearly rail-to-rail at the input and rail-to-rail at the output enables designers to buffer CMOS DACs, ASICs, and other wide output swing devices in singlesupply systems. The outputs remain stable with capacitive loads of more than 500 pF. The AD8641 is suitable for applications utilizing multichannel boards that require low power to manage heat. Other applications include photodiodes, ATE reference level drivers, battery management, and industrial controls. The AD8641 is fully specified over the extended industrial temperature range of -40 to +125C. The AD8641 is available in 5-lead SC70 and 8-lead SOIC lead-free packages. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 (c) 2004 Analog Devices, Inc. All rights reserved. 05072-101 TOP VIEW (Not to Scale) AD8641 TABLE OF CONTENTS Specifications..................................................................................... 3 Electrical Characteristics ............................................................. 3 Absolute Maximum Ratings............................................................ 5 Typical Performance Characteristics ............................................. 6 Outline Dimensions ....................................................................... 12 Ordering Guide .......................................................................... 12 REVISION HISTORY 10/04--Initial Version: Revision 0 Rev. 0 | Page 2 of 12 AD8641 SPECIFICATIONS ELECTRICAL CHARACTERISTICS @ VS =5.0 V, VCM = 2.5 V, TA =25C, unless otherwise noted. Table 1. Parameter INPUT CHARACTERISTICS Offset Voltage Symbol VOS -40C < TA < +85C +85C < TA < +125C, VCM = 1.5 V Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density IB -40C < TA < +125C IOS -40C < TA < +125C CMRR AVO VOS/T VOH IL = 2 mA, -40C to +125C VOL IL = 2 mA, -40C to +125C IOUT PSRR ISY VS = 5 V to 26 V -40C < TA < +125C SR GBP OO eN p-p eN iN f = 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 2 3 50 4.0 28.5 0.5 90 0.01 6 107 195 VCM = 0 V to 2.5 V RL = 10 k, VO = 0.5 to 4.5 V -40C < TA < +125C 0 74 80 93 140 2.5 0.25 Conditions Min Typ 50 Max 750 1.5 1.6 1 180 0.5 50 3 Unit V mV mV pA pA pA pA V dB V/mV V/C V V V V mA dB A A V/s MHz Degrees V p-p nV/Hz fA/Hz 4.94 4.93 0.05 0.05 250 270 Rev. 0 | Page 3 of 12 AD8641 @ VS= 13 V, VCM = 0 V, TA =25C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Symbol VOS -40 < TA < +125C IB -40C < TA < +125C IOS -40C < TA < +125C CMRR AVO VOS/T VOH IL = 2 mA, -40C to +125C VOL IL = 2 mA, -40C to +125C IOUT PSRR ISY VS = 2.5 V to 13 V -40C < TA < +125C SR GBP OO eN p-p eN iN f = 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 3 3.5 60 4.2 27.5 0.5 90 12 107 200 VCM = -13 V to +10 V RL = 10 k, VO = -11 V to +11 V -40C < TA < +125C -13 90 215 107 290 2.5 0.25 Conditions Min Typ 70 Max 750 1.5 1 260 0.5 35 +10 Unit V mV pA pA pA pA V dB V/mV V/C V V V V mA dB A A V/s MHz Degrees V p-p nV/Hz fA/Hz +12.94 +12.93 +12.94 -12.93 290 330 Rev. 0 | Page 4 of 12 AD8641 ABSOLUTE MAXIMUM RATINGS Table 3. Absolute Maximum Ratings1 Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration Storage Temperature Range KS-5, R-8 Packages Operating Temperature Range Junction Temperature Range KS-5, R-8 Packages Lead Temperature Range (Soldering, 60 Sec) Rating 27.3 V VS- to VS+ Supply Voltage Indefinite -65C to +150C -40C to +125C -65C to +150C 300C Table 4. Package Type 5-Lead SC70 (KS-5) 8-Lead SOIC (R-8) JA2 331.4 157 JC 223.9 56 Units C/W C/W Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 1 2 Absolute maximum ratings apply at 25C, unless otherwise noted. JA is specified for the worst-case conditions, i.e., JA is specified for devices soldered on circuit boards for surface-mounted packages. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. 0 | Page 5 of 12 AD8641 TYPICAL PERFORMANCE CHARACTERISTICS 80 20 VSY = 13V 70 NUMBER OF AMPLIFIERS 18 16 VSY = 5V VCM = 1.5V 60 FREQUENCY 14 12 10 8 6 4 50 40 30 20 10 0 2 05072-002 05072-005 05072-007 05072-006 -0.60 -0.55 -0.50 -0.45 -0.40 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0 0 VOS (mV) TCVOS (V/C) Figure 3. Input Offset Voltage Figure 6. Offset Voltage Drift 16 4.5 VSY = 13V 14 NUMBER OF AMPLIFIERS 4.0 3.5 VSY = 13V TA = 25C 12 3.0 10 8 6 4 INPUT BIAS (pA) 2.5 2.0 1.5 1.0 0.5 2 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 0 05072-003 -0.5 -15 -13 -11 -9 -7 -5 -3 -1 1 3 5 7 9 11 13 15 OFFSET VOLTAGE (V/C) 10.0 VCM (V) Figure 4. Offset Voltage Drift Figure 7. Input Bias Current vs. VCM 70 0.5 VSY = 2.5V 60 0.4 0.3 VSY = 13V TA = 25C 50 INPUT BIAS (pA) 0.2 0.1 FREQUENCY 40 0 -0.1 -0.2 -0.3 30 20 10 -0.4 05072-004 -0.60 -0.55 -0.50 -0.45 -0.40 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0 -0.5 -15.0 -12.5 -10.0 -7.5 -5.0 -2.5 0 2.5 5.0 7.5 10.0 12.5 15.0 VOS (mV) VCM (V) Figure 5. Input Offset Voltage Rev. 0 | Page 6 of 12 Figure 8. Input Bias Current vs. VCM 10.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 AD8641 1000 VSY = 13V 500 VSY = 5V 400 300 INPUT BIAS CURRENT (pA) 100 200 VOS (V) 05072-008 100 0 -100 -200 10 1 -300 -400 05072-011 0.1 0 25 50 75 100 125 150 TEMPERATURE (C) -500 0 0.5 1.0 1.5 VCM (V) 2.0 2.5 Figure 9. Input Bias Current vs. Temperature Figure 12. Input Offset Voltage vs. VCM 1.0 0.8 0.6 0.4 INPUT BIAS (pA) OPEN-LOOP GAIN (V/V) 10M VSY = +5V OR 5V 1M VSY = 13V 0.2 0 -0.2 -0.4 -0.6 -0.8 05072-009 100k VSY = 2.5V -5 -4 -3 -2 -1 0 VCM (V) 1 2 3 4 5 1 10 100 LOAD RESISTANCE (k) Figure 10. Input Bias Current vs. VCM Figure 13. Open-Loop Gain vs. Load Resistance 1000 900 800 700 600 500 400 300 200 100 0 VSY = 13V 1000 A B C 100 AVO (V/mV) D E VOS (V) 10 A. VSY = 13V, VO = 11V, RL = 10k B. VSY = 13V, VO = 11V, RL = 2k C. VSY = +5V, VO = +0.5V/+4.5V, RL = 10k D. VSY = +5V, VO = +0.5V/+4.5V, RL = 2k E. VSY = +5V, VO = +0.5V/+4.5V, RL = 600 05072-010 -15 -13 -11 -9 -7 -5 -3 -1 0 1 3 5 7 9 11 13 15 -30 -10 10 30 50 70 90 110 130 150 VCM (V) TEMPERATURE (C) Figure 11. Input Offset Voltage vs. VCM Figure 14. Open-Loop Gain vs. Temperature Rev. 0 | Page 7 of 12 05072-013 -100 1 -50 05072-012 -1.0 10k 0.1 AD8641 600 500 400 SATURATION VOLTAGE (mV) OFFSET VOLTAGE (V) 10000 VSY = 13V VSY = 13V VSY - VOH 1000 300 200 100 0 -100 -200 -300 -400 -500 05072-014 100k 100 -VSY - VOL 10k 1k 10 -10 -5 0 5 10 15 0.01 0.1 1 10 100 OUTPUT VOLTAGE (V) LOAD CURRENT (mA) Figure 15. Input Error Voltage vs. Output Voltage for Resistive Loads Figure 18. Output Saturation Voltage vs. Load Current 250 200 150 100 INPUT VOLTAGE (V) 10000 VSY = 5V POS RAIL SATURATION VOLTAGE (mV) VSY = 5V VSY - VOH 1000 VOL 100 RL = 1k RL = 2k RL = 10k RL = 100k 50 0 -50 -100 -150 -200 -250 -300 -350 0 50 10 RL = 100k RL = 1k RL = 10k NEG RAIL RL = 2k 05072-015 100 150 200 250 300 350 0.01 0.1 1 10 100 OUTPUT VOLTAGE FROM SUPPLY RAIL (mV) LOAD CURRENT (mA) Figure 16. Input Error Voltage vs. Output Voltage Within 300 mV of Supply Rails Figure 19. Output Saturation Voltage vs. Load Current 800 700 600 500 70 60 50 40 GAIN VSY = 13V RL = 2k CL = 40pF 315 270 225 GAIN (dB) 30 20 10 0 -10 -20 PHASE ISY (A) 135 90 45 0 -45 -90 100k 1M FREQUENCY (Hz) 10M 400 300 200 -55C 100 0 4 8 12 16 VSY (V) 20 24 28 +25C +125C 05072-016 Figure 17. Quiescent Current vs. Supply Voltage at Different Temperatures Figure 20. Open-Loop Gain and Phase Margin vs. Frequency Rev. 0 | Page 8 of 12 05072-019 -30 10k -135 PHASE (Degrees) 180 05072-018 1 0.001 05072-017 -600 -15 1 0.001 AD8641 70 60 50 40 GAIN VSY = 5V RL = 2k CL = 40pF 315 270 225 140 120 100 PHASE (Degrees) VSY = 13V 180 135 90 PHASE 45 0 -45 -90 80 CMRR (dB) GAIN (dB) 30 20 10 0 -10 -20 -30 10k 100k 1M FREQUENCY (Hz) 10M 60 40 20 0 -20 -40 05072-020 10k 100k FREQUENCY (Hz) 1M 10M Figure 21. Open-Loop Gain and Phase Margin vs. Frequency Figure 24. CMRR vs. Frequency 70 60 50 40 G = +100 GAIN (dB) CMRR (dB) 30 20 G = +10 10 0 G = +1 -10 -20 10k 100k FREQUENCY (Hz) 1M 10M 05072-021 VSY = 13V RL = 2k CL = 40pF 140 120 100 80 60 40 20 0 -20 -40 10k 100k FREQUENCY (Hz) 1M 10M 05072-024 05072-025 VSY = 5V -30 1k -60 1k Figure 22. Closed-Loop Gain vs. Frequency Figure 25. CMRR vs. Frequency 70 60 50 40 G = +100 GAIN (dB) PSRR (dB) 140 VSY = 5V RL = 2k CL = 40pF 120 100 80 60 40 20 0 -20 -40 10k 100k FREQUENCY (Hz) 1M 10M 05072-022 VSY = 13V +PSRR 30 20 G = +10 10 0 G = +1 -10 -20 -30 1k -PSRR -60 1k 10k 100k FREQUENCY (Hz) 1M 10M Figure 23. Closed-Loop Gain vs. Frequency Figure 26. PSRR vs. Frequency Rev. 0 | Page 9 of 12 05072-023 -135 -60 1k AD8641 140 120 100 +PSRR 80 PSRR (dB) 1.0 VSY = 5V T VSY = 13V 0.8 0.6 1 0.4 INPUT BIAS (pA) VIN 60 40 20 0 -20 -40 10k 100k FREQUENCY (Hz) 1M 10M 05072-026 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 CH1 -4 10.0V -3 CH2 -2 10.0V-1 -5 M400s CH1 4 1.00V 0 1 2 A3 5 T 0.00000s VCM (V) 2 -PSRR VOUT 05072-029 Figure 27. PSRR vs. Frequency Figure 30. No Phase Reversal 1000 15 VSY = 13V G = +100 100 OUTPUT SWING (V) VS = 13V GAIN = +5 10 TS + (1%) 5 TS + (0.1%) ZOUT () 10 G = +10 1 G = +1 0.1 0 -5 TS - (0.1%) -10 TS - (1%) 05072-027 10k 100k 1M 10M 100M 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 FREQUENCY (Hz) SETTLING TIME (s) Figure 28. Output Impedance vs. Frequency Figure 31. Output Swing and Error vs. Settling Time 1000 70 VSY = 5V G = +100 100 60 50 VS = 13V RL = 10k VIN = 100mV p-p AV = +1 ZOUT () 10 G = +10 1 OVERSHOOT (%) 40 30 OS- OS+ 20 G = +1 0.1 10 0.01 1k 05072-028 10k 100k 1M 10M 100M 1 10 100 1000 FREQUENCY (Hz) CAPACITANCE (pF) Figure 29. Output Impedance vs. Frequency Figure 32. Small Signal Overshoot vs. Load Capacitance Rev. 0 | Page 10 of 12 05072-031 0 05072-030 0.01 1k -15 05072-009 -60 1k AD8641 70 VS = 2.5V RL = 10k VIN = 100mV p-p AV = +1 1k VSY = 13V 60 50 OVERSHOOT (%) VOLTAGE NOISE DENSITY (nV/ Hz) 05072-032 100 40 30 20 OS- OS+ 10 10 0 1 10 100 1000 CAPACITANCE (pF) 10 100 FREQUENCY (Hz) 1k 10k Figure 33. Small Signal Overshoot vs. Load Capacitance Figure 36. Voltage Noise Density 1.0 0.8 0.6 0.4 INPUT BIAS (pA) 1k VS = 13V G = +1M CH1 p-p = 4.26V VSY = 5V VOLTAGE NOISE DENSITY (nV/ Hz) 100 0.2 1 0 -0.2 -0.4 -0.6 -0.8 -1.0 CH1 -4 1.00V -3 -5 -2 -1 M1.00s 0 1 VCM (V) 2 A CH1 3 -20.0V 4 5 05072-033 10 05072-009 10 100 FREQUENCY (Hz) 1k 10k Figure 34. 0.1 Hz to 10 Hz Noise Figure 37. Voltage Noise Density 1.0 0.8 0.6 0.004 VS = 2.5V G = +1M CH1 p-p = 4.06V 0.001 VSY = 13V LOAD = 100k GAIN = +1 8V p-p INPUT INPUT BIAS (pA) 0.2 1 0 THD + NOISE (%) 0.4 1V p-p INPUT 0.0001 2V p-p INPUT 4V p-p INPUT -0.2 -0.4 -0.6 -0.8 -1.0 CH1 -4 1.00V -3 -5 -2 -1 M1.00s 0 1 VCM (V) 2 A CH1 3 -20.0V 4 5 05072-034 0.00001 05072-009 1 100 1k FREQUENCY (Hz) 10k 20k Figure 35. 0.1 Hz to 10 Hz Noise Figure 38. Total Harmonic Distortion + Noise vs. Frequency Rev. 0 | Page 11 of 12 05072-037 0.000001 05072-036 1 05072-035 1 AD8641 OUTLINE DIMENSIONS 2.00 BSC 5 4 1.25 BSC 1 2 3 2.10 BSC PIN 1 1.00 0.90 0.70 0.65 BSC 1.10 MAX 0.22 0.08 0.30 0.15 0.10 COPLANARITY COMPLIANT TO JEDEC STANDARDS MO-203AA SEATING PLANE 0.10 MAX 0.46 0.36 0.26 Figure 39. 5-Lead Thin Shrink Small Outline Transistor Package [SC70] (KS-5) Dimensions shown in millimeters 5.00 (0.1968) 4.80 (0.1890) 8 5 4 4.00 (0.1574) 3.80 (0.1497) 1 6.20 (0.2440) 5.80 (0.2284) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 1.75 (0.0688) 1.35 (0.0532) 0.50 (0.0196) x 45 0.25 (0.0099) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN Figure 40. 8-Lead Standard Small Outline Package [SOIC] (R-8) Dimensions shown in millimeters ORDERING GUIDE Model AD8641AKSZ-R21 AD8641AKSZ-Reel71 AD8641AKSZ-Reel1 AD8641ARZ1 AD8641ARZ-Reel71 AD8641ARZ-Reel1 1 Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package Description 5-Lead SC70 5-Lead SC70 5-Lead SC70 8-lead SOIC 8-lead SOIC 8-lead SOIC Package Option KS-5 KS-5 KS-5 R-8 R-8 R-8 Branding A07 A07 A07 Z = Pb-free part. (c) 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05072-0-10/04(0) Rev. 0 | Page 12 of 12 |
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