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Precision Low Noise CMOS Rail-to-Rail Input/Output Operational Amplifiers AD8605/AD8606/AD8608 FEATURES Low offset voltage: 65 V maximum Low input bias currents: 1 pA maximum Low noise: 8 nV/Hz Wide bandwidth: 10 MHz High open-loop gain: 120 dB Unity gain stable Single-supply operation: 2.7 V to 5.5 V MicroCSPTM APPLICATIONS Photodiode amplification Battery-powered instrumentation Multipole filters Sensors Barcode scanners Audio GENERAL DESCRIPTION The AD8605, AD8606, and AD86081 are single, dual, and quad rail-to-rail input and output, single-supply amplifiers. They feature very low offset voltage, low input voltage and current noise, and wide signal bandwidth. They use Analog Devices' patented DigiTrim(R) trimming technique, which achieves superior precision without laser trimming. The combination of low offsets, low noise, very low input bias currents, and high speed makes these amplifiers useful in a wide variety of applications. Filters, integrators, photodiode amplifiers, and high impedance sensors all benefit from the combination of performance features. Audio and other ac applications benefit from the wide bandwidth and low distortion. Applications for these amplifiers include optical control loops, portable and loop-powered instrumentation, and audio amplification for portable devices. The AD8605, AD8606, and AD8608 are specified over the extended industrial temperature range (-40C to +125C). The AD8605 single is available in the 5-lead SOT-23 and 5-bump MicroCSP packages. The 5-bump MicroCSP offers the smallest available footprint for any surface-mount operational amplifier. The AD8606 dual is available in an 8-lead MSOP package and a narrow SOIC surface-mount package. The AD8608 quad is available in a 14-lead TSSOP and a narrow 14-lead SOIC package. MicroCSP, SOT, MSOP, and TSSOP versions are available in tape and reel only. OUT 1 V- 2 +IN 3 FUNCTIONAL BLOCK DIAGRAMS 5 V+ OUT A 1 -IN A 2 4 -IN 02731-D-001 8 V+ AD8605 AD8608 7 OUT B 5 +IN B 02731-D-005 02731-D-004 +IN A 3 V- 4 6 -IN B Figure 1. 5-Lead SOT-23 (RT Suffix) TOP VIEW (BUMP SIDE DOWN) OUT 1 V- 2 +IN 3 -IN 4 02731-D-006 Figure 2. 8-Lead SOIC (R Suffix) OUT A 1 -IN A 2 14 OUT D 13 -IN D 12 +IN D V+ 5 +IN A 3 V+ 4 +IN B 5 -IN B 6 OUT B 7 AD8608 11 V- 10 +IN C 9 -IN C 8 OUT C AD8605 ONLY Figure 3. 5-Bump MicroCSP (CB Suffix) OUT A -IN A +IN A V- 1 4 8 5 V+ OUT B -IN B +IN B Figure 4. 14-Lead SOIC (R Suffix) AD8606 7 8 Figure 5. 8-Lead MSOP (RM Suffix) Figure 6. 14-Lead TSSOP (RU Suffix) 1 Protected by U.S. Patent No. 5,969,657; other patents pending. Rev. D 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. 02731-D-002 OUT A -IN A +IN A V+ +IN B -IN B OUT B 1 14 AD8608 OUT D -IN D +IN D V- +IN C -IN C OUT C 02731-D-003 AD8605/AD8606/AD8608 TABLE OF CONTENTS 5 V Electrical Specifications ............................................................ 3 2.7 V Electrical Specifications ......................................................... 5 Absolute Maximum Ratings............................................................ 6 ESD Caution.................................................................................. 6 Typical Performance Characteristics ............................................. 7 Application Information................................................................ 13 Output Phase Reversal............................................................... 13 Maximum Power Dissipation ................................................... 13 Input Overvoltage Protection ................................................... 13 THD + Noise............................................................................... 13 Total Noise Including Source Resistors ................................... 14 REVISION HISTORY 5/04--Data Sheet Changed from Rev. C to Rev. D Updated Format............................................................. Universal Edit to Light Sensitivity Section ............................................... 16 Updated Outline Dimensions ................................................... 19 Changes to Ordering Guide ...................................................... 20 7/03--Data Sheet Changed from Rev. B to Rev. C Changes to Features....................................................................... 1 Change to General Description ................................................... 1 Addition to Functional Block Diagrams .................................... 1 Addition to Absolute Maximum Ratings ................................... 4 Addition to Ordering Guide ........................................................ 4 Change to Equation In Maximum Power Dissipation Section........................................................................................ 11 Added Light Sensitivity Section................................................. 12 Added New Figure 8 and Renumbered Subsequent Figures . 13 Added New MicroCSP Assembly Considerations Section .... 13 Changes to Figure 9..................................................................... 13 Change to Equation in Photodiode Preamplifier Applications Section ................................................................ 13 Changes to Figure 12................................................................... 14 Change to Equation in D/A Conversion Section .................... 14 Updated Outline Dimensions ................................................... 15 3/03--Data Sheet Changed from Rev. A to Rev. B Changes to Functional Block Diagram....................................... 1 Changes to Absolute Maximum Ratings .................................... 4 Changes to Ordering Guide ....................................................... 4 Changes to Figure 9 .................................................................... 13 Updated Outline Dimensions.................................................... 15 11/02--Data Sheet Changed from Rev. 0 to Rev. A Change to Electrical Characteristics ........................................... 2 Changes to Absolute Maximum Ratings .................................... 4 Changes Ordering Guide ............................................................. 4 Change to TPC 6 .......................................................................... 5 Updated Outline Dimensions.................................................... 15 Channel Separation.................................................................... 14 Capacitive Load Drive ............................................................... 14 Light Sensitivity .......................................................................... 15 MicroCSP Assembly Considerations....................................... 15 I-V Conversion Applications ........................................................ 16 Photodiode Preamplifier Applications .................................... 16 Audio and PDA Applications ................................................... 16 Instrumentation Amplifiers ...................................................... 17 D/A Conversion ......................................................................... 17 Outline Dimensions ....................................................................... 18 Ordering Guide .......................................................................... 19 Rev. D | Page 2 of 20 AD8605/AD8606/AD8608 5 V ELECTRICAL SPECIFICATIONS Table 1. @ VS = 5 V, VCM = VS/2, TA = 25C, unless otherwise noted. Parameter INPUT CHARACTERISTICS Offset Voltage AD8605/AD8606 AD8608 Symbol VOS VS = 3.5 V, VCM = 3 V VS = 3.5 V, VCM = 2.7 V VS = 5 V, VCM = 0 V to 5 V -40C < TA < +125C IB -40C < TA < +85C -40C < TA < +125C -40C < TA < +85C -40C < TA < +125C IOS -40C < TA < +85C -40C < TA < +125C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift AD8605/AD8606 AD8608 INPUT CAPACITANCE Common-Mode Input Capacitance Differential Input Capacitance OUTPUT CHARACTERISTICS Output Voltage High CMRR AVO VCM = 0 V to 5 V -40C < TA < +125C VO = 0.5 V to 4.5 V RL = 2 k, VCM = 0 V 0 85 75 300 100 90 1,000 0.1 20 20 80 0.2 65 75 300 750 1 50 250 100 300 0.5 20 75 5 V V V V pA pA pA pA pA pA pA pA V dB dB V/mV Conditions Min Typ Max Unit Input Bias Current AD8605/AD8606 AD8605/AD8606 AD8608 AD8608 Input Offset Current VOS/T VOS/T 1 1.5 8.8 2.59 4.5 6.0 V/C V/C pF pF V V V mV mV mV mA VOH Output Voltage Low VOL IL = 1 mA IL = 10 mA -40C < TA < +125C IL = 1 mA IL= 10 mA -40C < TA < +125C f = 1 MHz, AV = 1 4.96 4.7 4.6 4.98 4.79 20 170 80 10 40 210 290 Output Current Closed-Loop Output Impedance POWER SUPPLY Power Supply Rejection Ratio AD8605/AD8606 AD8608 Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time Full Power Bandwidth Gain Bandwidth Product Phase Margin IOUT ZOUT PSRR ISY VS = 2.7 V to 5.5 V VS = 2.7 V to 5.5 V -40C < TA < +125C VO = 0 V -40C < TA < +125C RL = 2 k To 0.01%, 0 V to 2 V step < 1% distortion 80 77 70 95 92 90 1 1.2 1.4 dB dB dB mA mA V/s s kHz MHz Degrees SR tS BWP GBP O 5 <1 360 10 65 Rev. D | Page 3 of 20 AD8605/AD8606/AD8608 Parameter NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Voltage Noise Density Current Noise Density Symbol en p-p en en in Conditions f = 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 1 kHz Min Typ 2.3 8 6.5 0.01 Max 3.5 12 Unit V p-p nV/Hz nV/Hz pA/Hz Rev. D | Page 4 of 20 AD8605/AD8606/AD8608 2.7 V ELECTRICAL SPECIFICATIONS Table 2. @ VS = 2.7 V, VCM = VS/2, TA = 25C, unless otherwise noted. Parameter INPUT CHARACTERISTICS Offset Voltage AD8605/AD8606 AD8608 Symbol VOS VS = 3.5 V, VCM = 3 V VS = 3.5 V, VCM = 2.7 V VS = 2.7 V, VCM = 0 V to 2.7 V -40C < TA < +125C IB -40C < TA < +85C -40C < TA < +125C -40C < TA < +85C -40C < TA < +125C IOS -40C < TA < +85C -40C < TA < +125C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift AD8605/AD8606 AD8608 INPUT CAPACITANCE Common-Mode Input Capacitance Differential Input Capacitance OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current Closed-Loop Output Impedance POWER SUPPLY Power Supply Rejection Ratio AD8605/AD8606 AD8608 Supply Current/Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Voltage Noise Density Current Noise Density CMRR AVO VOS/T VOS/T VCM = 0 V to 2.7 V -40C < TA < +125C RL = 2 k, VO= 0.5 V to 2.2 V 0 80 70 110 95 85 350 1 1.5 8.8 2.59 VOH VOL IOUT ZOUT PSRR VS = 2.7 V to 5.5 V VS = 2.7 V to 5.5 V -40C < TA < +125C VO = 0 V -40C < TA < +125C RL = 2 k To 0.01%, 0 V to 1 V step 80 77 70 95 92 90 1.15 dB dB dB mA mA V/s s MHz Degrees 3.5 12 V p-p nV/Hz nV/Hz pA/Hz IL = 1 mA -40C < TA < +125C IL = 1 mA -40C < TA < +125C f = 1 MHz, AV = 1 2.6 2.6 2.66 25 30 12 40 50 4.5 6.0 0.1 20 20 80 0.2 65 75 300 750 1 50 250 100 300 0.5 20 75 2.7 V V V V pA pA pA pA pA pA pA pA V dB dB V/mV V/C V/C pF pF V V mV mV mA Conditions Min Typ Max Unit Input Bias Current AD8605/AD8606 AD8605/AD8606 AD8608 AD8608 Input Offset Current ISY 1.4 1.5 SR tS GBP O en p-p en en in 5 < 0.5 9 50 2.3 8 6.5 0.01 f = 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 1 kHz Rev. D | Page 5 of 20 AD8605/AD8606/AD8608 ABSOLUTE MAXIMUM RATINGS 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. Table 3. Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration to GND Storage Temperature Range All Packages Operating Temperature Range AD8605/AD8606/AD8608 Junction Temperature Range All Packages Lead Temperature Range (Soldering, 60 sec) Rating 6V GND to VS 6V Observe Derating Curves Table 4. Package Type Package Type 5-Bump MicroCSP (CB) 5-Lead SOT-23 (RT) 8-Lead MSOP (RM) 8-Lead SOIC (R) 14-Lead SOIC (R) 14-Lead TSSOP (RU) JA1 220 230 210 158 120 180 JC 220 92 45 43 36 35 Unit C/W C/W C/W C/W C/W C/W 1 JA is specified for worst-case conditions, i.e., JA is specified for device in socket for PDIP packages; JA is specified for device soldered onto a circuit board for surface-mount packages. -65C to +150C -40C to +125C -65C to +150C 300C 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. D | Page 6 of 20 AD8605/AD8606/AD8608 TYPICAL PERFORMANCE CHARACTERISTICS 4500 VS = 5V 4000 TA = 25C VCM = 0V TO 5V 3500 300 VS = 5V TA = 25C INPUT OFFSET VOLTAGE (mV) 200 NUMBER OF AMPLIFIERS 3000 2500 2000 1500 1000 500 0 -300 02731-D-007 100 0 -100 -300 COMMON-MODE VOLTAGE (V) -200 -100 0 100 OFFSET VOLTAGE (mV) 200 300 Figure 7. Input Offset Voltage Distribution 24 VS = 5V TA = -40C TO +125C VCM = 2.5V INPUT BIAS CURRENT (pA) Figure 10. Input Offset Voltage vs. Common-Mode Voltage (200 Units, 5 Wafer Lots, Including Process Skews) 360 VS = 2.5V 320 280 240 AD8605/AD8606 200 160 AD8608 120 80 40 0 0 25 50 75 TEMPERATURE (C) 100 02731-D-011 20 NUMBER OF AMPLIFIERS 16 12 8 0 0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 TCVOS (mV/C) 3.6 4.0 4.4 4.8 02731-D-008 4 125 Figure 8. AD8608 Input Offset Voltage Drift Distribution 20 18 16 NUMBER OF AMPLIFIERS Figure 11. Input Bias Current vs. Temperature 1k VS = 5V TA = 25C 100 VSY-VOUT (mV) VS = 5V TA = -40C TO +125C VCM = 2.5V 14 12 10 8 6 4 02731-D-009 10 SOURCE 1 SINK 2 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 TCVOS (mV/C) 0.1 0.001 0.01 0.1 LOAD CURRENT (mA) 1 10 Figure 9. AD8605/AD8606 Input Offset Voltage Drift Distribution Figure 12. Output Voltage to Supply Rail vs. Load Current Rev. D | Page 7 of 20 02731-D-012 02731-D-010 -200 AD8605/AD8606/AD8608 5.000 VOH @ 1mA LOAD VS = 5V 4.900 6 4.950 OUTPUT VOLTAGE (V) 5 OUTPUT SWING (V p-p) 4 4.850 3 VS = 5V VIN = 4.9V p-p TA = 25C RL = 2k AV = 1 4.800 VOH @ 10mA LOAD 02731-D-013 2 4.700 -40 -25 -10 5 20 35 50 65 80 95 110 125 0 1k 10k TEMPERATURE (C) 100k FREQUENCY (Hz) 1M 10M Figure 13. Output Voltage Swing vs. Temperature 0.250 VS = 5V 0.200 OUTPUT IMPEDANCE () OUTPUT VOLTAGE (V) Figure 16. Closed-Loop Output Voltage Swing 100 VS = 2.5V VOH @ 10mA LOAD 90 80 70 AV = 100 60 50 AV = 10 40 30 20 AV = 1 0.150 0.100 0.050 VOH @ 1mA LOAD 0 -40 02731-D-014 10 0 1k 10k 100k 1M FREQUENCY (Hz) 10M -25 -10 5 20 35 50 65 80 95 110 125 100M TEMPERATURE (C) Figure 14. Output Voltage Swing vs. Temperature 100 80 60 40 VS = 2.5V RL = 2kV CL = 20pF fM = 648 225 180 135 90 Figure 17. Output Impedance vs. Frequency 120 VS = 2.5V 110 100 90 PHASE (Degrees) GAIN (dB) 20 0 -20 -40 -60 -80 45 0 -45 -90 CMRR (dB) 80 70 60 50 40 -135 02731-D-015 -180 100k 1M FREQUENCY (Hz) 10M -225 100M 30 20 1k -100 10k 10k 100k 1M FREQUENCY (Hz) 10M Figure 15. Open-Loop Gain and Phase vs. Frequency Figure 18. Common-Mode Rejection Ratio vs. Frequency Rev. D | Page 8 of 20 02731-D-018 02731-D-017 02731-D-016 4.750 1 AD8605/AD8606/AD8608 140 VS = 5V 120 100 80 PSRR (dB) 1.0 0.9 SUPPLY CURRENT/AMPLIFIER (mA) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 02731-D-022 60 40 20 0 -20 -40 -60 1k 02731-D-019 10k 100k FREQUENCY (Hz) 1M 10M Figure 19. PSRR vs. Frequency 45 40 SMALL SIGNAL OVERSHOOT (%) Figure 22. Supply Current vs. Supply Voltage VS = 5V 30 25 +OS 20 -OS 15 10 5 0 10 02731-D-020 VOLTAGE NOISE (1V/DIV) 35 VS = 5V RL = TA = 25C AV = 1 100 CAPACITANCE (pF) 1k TIME (1s/DIV) Figure 20. Small Signal Overshoot vs. Load Capacitance 2.0 1.5 VS = 2.7V Figure 23. 0.1 Hz to 10 Hz Input Voltage Noise VS = 2.5V RL = 10k CL = 200pF AV = 1 SUPPLY CURRENT/AMPLIFIER (mA) 1.0 0.5 0 VS = 5V -0.5 02731-D-021 VOLTAGE (50mV/DIV) -1.0 -1.5 -50 -35 -20 5 20 35 50 65 TEMPERATURE (C) 80 95 110 125 TIME (200ns/DIV) Figure 21. Supply Current vs. Temperature Figure 24. Small Signal Transient Response Rev. D | Page 9 of 20 02731-D-024 02731-D-023 AD8605/AD8606/AD8608 36 VS = 2.5V RL = 10k CL = 200pF AV = 1 VS = 2.5V 32 28 24 20 16 12 8 4 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 FREQUENCY (kHz) 02731-D-028 TIME (400ns/DIV) 02731-D-025 VOLTAGE NOISE DENSITY (nV/Hz) VOLTAGE (1V/DIV) 1.0 Figure 25. Large Signal Transient Response 53.6 Figure 28. Voltage Noise Density VS = 2.5V VOLTAGE NOISE DENSITY (nV/Hz) +2.5V VS = 2.5V RL = 10k AV = 100 VIN = 50mV 46.9 40.2 33.5 26.8 20.1 13.4 6.7 0 0 1 2 3 4 5 6 FREQUENCY (kHz) 7 8 9 10 02731-D-029 0V 0V -50mV 02731-D-026 TIME (400ns/DIV) Figure 26. Negative Overload Recovery Figure 29. Voltage Noise Density VOLTAGE NOISE DENSITY (nV/Hz) VS = 2.5V RL = 10k AV = 100 VIN = 50mV 0V 0V +2.5V 119.2 VS = 2.5V 104.3 99.4 74.5 59.6 44.7 29.8 14.9 0 0 10 20 30 40 50 60 FREQUENCY (Hz) 70 80 90 02731-D-030 -50mV 02731-D-027 TIME (400ns/DIV) 100 Figure 27. Positive Overload Recovery Figure 30. Voltage Noise Density Rev. D | Page 10 of 20 AD8605/AD8606/AD8608 1800 1600 1400 OUTPUT VOLTAGE (V) 2.680 VS = 2.7V TA = 25C VCM = 0V TO 2.7V VS = 2.7V 2.675 NUMBER OF AMPLIFIERS 1200 1000 800 600 400 02731-D-031 2.670 2.665 VOH @ 1mA LOAD 2.660 200 0 -300 -200 0 100 -100 OFFSET VOLTAGE (V) 200 300 2.650 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (C) Figure 31. Input Offset Voltage Distribution 300 VS = 2.7V TA = 25C 200 INPUT OFFSET VOLTAGE (V) Figure 34. Output Voltage Swing vs. Temperature 0.045 VS = 2.7V 0.040 0.035 100 OUTPUT VOLTAGE (V) 0.030 0.025 0.020 0.015 0.010 VOH @ 1mA LOAD 0 -100 02731-D-032 0.005 0 -40 -300 0 0 0.9 1.8 2.7 -25 -10 5 20 35 50 65 80 95 110 125 COMMON-MODE VOLTAGE (V) TEMPERATURE (C) Figure 32. Input Offset Voltage vs. Common-Mode Voltage (200 Units, 5 Wafer Lots, Including Process Skews) 1k VS = 2.7V TA = 25C 100 40 20 0 -20 -40 100 80 60 Figure 35. Output Voltage Swing vs. Temperature 225 VS = 1.35V RL = 2k CL = 20pF fM = 52.5 180 135 90 45 0 -45 -90 -135 -180 -225 100M 02731-D-036 OUTPUT VOLTAGE (mV) SOURCE 10 SINK 1 -60 02731-D-033 -80 -100 10k 0.1 0.001 0.01 0.1 LOAD CURRENT (mA) 1 10 100k 1M FREQUENCY (Hz) 10M Figure 33. Output Voltage to Supply Rail vs. Load Current Figure 36. Open-Loop Gain and Phase vs. Frequency Rev. D | Page 11 of 20 PHASE (Degrees) GAIN (dB) 02731-D-035 -200 02731-D-034 2.655 AD8605/AD8606/AD8608 3.0 VS = 2.7V 2.5 OUTPUT SWING (V p-p) 2.0 1.5 VS = 2.7V VIN = 2.6V p-p TA = 25C RL = 2k AV = 1 1.0 0 1k 10k 100k FREQUENCY (Hz) 1M 02731-D-037 10M TIME (1s/DIV) Figure 37. Closed-Loop Output Voltage Swing vs. Frequency 100 90 80 VS = 1.35V Figure 40. 0.1 Hz to 10 Hz Input Voltage Noise VS = 1.35V RL = 10k CL = 200pF AV = 1 OUTPUT IMPEDANCE () 70 60 50 40 30 20 10 0 1k 10k 100k 1M FREQUENCY (Hz) 10M 02731-D-038 AV = 100 AV = 10 AV = 1 02731-D-041 VOLTAGE (50mV/DIV) 100M TIME (200ns/DIV) Figure 38. Output Impedance vs. Frequency 60 VS = 2.7V TA = 25C AV = 1 Figure 41. Small Signal Transient Response VS = 1.35V RL = 10k CL = 200pF AV = 1 SMALL SIGNAL OVERSHOOT (%) 50 40 -OS 30 +OS 20 0 10 100 CAPACITANCE (pF) 1k 02731-D-039 TIME (400ns/DIV) Figure 39. Small Signal Overshoot vs. Load Capacitance Figure 42. Large Signal Transient Response Rev. D | Page 12 of 20 02731-D-042 10 VOLTAGE (1V/DIV) 02731-D-040 0.5 VOLTAGE NOISE (1V/DIV) AD8605/AD8606/AD8608 APPLICATION INFORMATION OUTPUT PHASE REVERSAL Phase reversal is defined as a change in polarity at the output of the amplifier when a voltage that exceeds the maximum input common-mode voltage drives the input. Phase reversal can cause permanent damage to the amplifier; it may also cause system lockups in feedback loops. The AD8605 does not exhibit phase reversal even for inputs exceeding the supply voltage by more than 2 V. VS = 2.5V VIN = 5V p-p AV = 1 RL = 10k Figure 44 compares the maximum power dissipation with temperature for the various AD8605 family packages. 2.0 1.8 SOIC-14 1.6 POWER DISSIPATION (W) 1.4 SOIC-8 1.2 1.0 0.8 0.6 0.4 0.2 MSOP SOT-23 TSSOP 02731-D-044 VOUT VOLTAGE (2V/DIV) VIN 0 0 20 40 60 TEMPERATURE (C) 80 100 Figure 44. Maximum Power Dissipation vs. Temperature 02731-D-043 INPUT OVERVOLTAGE PROTECTION The AD8605 has internal protective circuitry. However, if the voltage applied at either input exceeds the supplies by more than 2.5 V, external resistors should be placed in series with the inputs. The resistor values can be determined by the formula TIME (4s/DIV) Figure 43. No Phase Reversal MAXIMUM POWER DISSIPATION Power dissipated in an IC causes the die temperature to increase. This can affect the behavior of the IC and the application circuit performance. The absolute maximum junction temperature of the AD8605/ AD8606/AD8608 is 150C. Exceeding this temperature could cause damage or destruction of the device. The maximum power dissipation of the amplifier is calculated according to the following formula: (VIN - VS ) 5mA (RS + 200 ) The remarkable low input offset current of the AD8605 (<1 pA) allows the use of larger value resistors. With a 10 k resistor at the input, the output voltage has less than 10 nV of error voltage. A 10 k resistor has less than 13 nV/Hz of thermal noise at room temperature. THD + NOISE Total harmonic distortion is the ratio of the input signal in V rms to the total harmonics in V rms throughout the spectrum. Harmonic distortion adds errors to precision measurements and adds unpleasant sonic artifacts to audio systems. The AD8605 has a low total harmonic distortion. Figure 45 shows that the AD8605 has less than 0.005% or -86 dB of THD + N over the entire audio frequency range. The AD8605 is configured in positive unity gain, which is the worst case, and with a load of 10 k. PDISS = where: TJ - TA JA TJ = junction temperature TA = ambient temperature JA = junction to-ambient-thermal resistance Rev. D | Page 13 of 20 AD8605/AD8606/AD8608 0.1 VSY = 2.5V AV = 1 BW = 22kHz The AD8606 has a channel separation of greater than -160 dB up to frequencies of 1 MHz, allowing the two amplifiers to amplify ac signals independently in most applications. 0 -20 CHANNEL SEPARATION (dB) 0.01 THD + N (%) -40 -60 -80 -100 -120 -140 -160 -180 100 02731-D-046 0.001 0.0001 20 100 1k FREQUENCY (Hz) 10k 20k Figure 45. THD + N TOTAL NOISE INCLUDING SOURCE RESISTORS The low input current noise and input bias current of the AD8605 make it the ideal amplifier for circuits with substantial input source resistance such as photodiodes. Input offset voltage increases by less than 0.5 nV per 1 k of source resistance at room temperature and increases to 10 nV at 85C. The total noise density of the circuit is en,TOTAL = en2 + (in RS ) 2 + 4k TRS 02731-D-045 1k 10k 100k FREQUENCY (Hz) 1M 10M 100M Figure 46. Channel Separation vs. Frequency CAPACITIVE LOAD DRIVE The AD8605 can drive large capacitive loads without oscillation. Figure 47 shows the output of the AD8606 in response to a 200 mV input signal. In this case, the amplifier was configured in positive unity gain, worst case for stability, while driving a 1,000 pF load at its output. Driving larger capacitive loads in unity gain may require the use of additional circuitry. VS = 2.5V AV = 1 RL = 10k CL = 1 VOLTAGE (100mV/DIV) where: en is the input voltage noise density of the AD8605 in is the input current noise density of the AD8605 RS is the source resistance at the noninverting terminal k is Boltzmann's constant (1.38 x 10-23 J/K) T is the ambient temperature in Kelvin (T = 273 + C) For example, with RS = 10 k, the total voltage noise density is roughly 15 nV/Hz. For RS < 3.9 k, en dominates and en,TOTAL en. The current noise of the AD8605 is so low that its total density does not become a significant term unless RS is greater than 6 M. The total equivalent rms noise over a specific bandwidth is expressed as TIME (10s/DIV) Figure 47. Capacitive Load Drive without Snubber En = (en,TOTAL ) BW where BW is the bandwidth in hertz. Note that the analysis above is valid for frequencies greater than 100 Hz and assumes relatively flat noise, above 10 kHz. For lower frequencies, flicker noise (1/f) must be considered. A snubber network, shown in Figure 48, helps reduce the signal overshoot to a minimum and maintain stability. Although this circuit does not recover the loss of bandwidth induced by large capacitive loads, it greatly reduces the overshoot and ringing. This method does not reduce the maximum output swing of the amplifier. Figure 49 shows a scope photograph of the output at the snubber circuit. The overshoot is reduced from over 70% to less than 5%, and the ringing is eliminated by the snubber. Optimum values for RS and CS are determined experimentally. CHANNEL SEPARATION Channel separation, or inverse crosstalk, is a measure of the signal feed from one amplifier (channel) to an other on the same IC. Rev. D | Page 14 of 20 02731-D-047 AD8605/AD8606/AD8608 V+ 4 2 200mV VIN 3 1 RS 8 V- CS RL CL shown in Figure 50 are not normal for most applications, i.e., even though direct sunlight can have intensities of 50 mW/cm2, office ambient light can be as low as 0.1 mW/cm2. When the MicroCSP package is assembled on the board with the bump-side of the die facing the PCB, reflected light from the PCB surface is incident on active silicon circuit areas and results in the increased IB. No performance degradation occurs due to illumination of the backside (substrate) of the AD8605ACB. The AD8605ACB is particularly sensitive to incident light with wavelengths in the near infrared range (NIR, 700 nm to 1000 nm). Photons in this waveband have a longer wavelength and lower energy than photons in the visible (400 nm to 700 nm) and near ultraviolet bands (NUV, 200 nm to 400 nm); therefore, they can penetrate more deeply into the active silicon. Incident light with wavelengths greater than 1100 nm has no photoelectric effect on the AD8605ACB because silicon is transparent to wave lengths in this range. The spectral content of conventional light sources varies: sunlight has a broad spectral range, with peak intensity in the visible band that falls off in the NUV and NIR bands; fluorescent lamps have significant peaks in the visible but not in the NUV or NIR bands. Efforts have been made at a product level to reduce the effect of ambient light; the under bump metal (UBM) has been designed to shield the sensitive circuit areas on the active side (bump-side) of the die. However, if an application encounters any light sensitivity with the AD8605ACB, shielding the bump side of the MicroCSP package with opaque material should eliminate this effect. Shielding can be accomplished using materials such as silica filled liquid epoxies that are used in flip chip underfill techniques. 5000 4500 4000 INPUT BIAS CURRENT (pA) AD8605 Figure 48. Snubber Network Configuration VS = 2.5V AV = 1 RL = 10k RS = 90 CL = 1,000pF CS = 700pF VOLTA (100mV/DIV) GE TIME (10s/DIV) Figure 49. Capacitive Load Drive with Snubber Table 5 summarizes a few optimum values for capacitive loads. Table 5. CL (pF) 500 1,000 2,000 RS () 100 70 60 CS (pF) 1,000 1,000 800 An alternate technique is to insert a series resistor inside the feedback loop at the output of the amplifier. Typically, the value of this resistor is approximately 100 . This method also reduces overshoot and ringing but causes a reduction in the maximum output swing. 02731-D-048 02731-D-049 3500 3000 2500 3mW/cm2 LIGHT SENSITIVITY The AD8605ACB (MicroCSP package option) is essentially a silicon die with additional post fabrication dielectric and intermetallic processing designed to contact solder bumps on the active side of the chip. With this package type, the die is exposed to ambient light and is subject to photoelectric effects. Light sensitivity analysis of the AD8605ACB mounted on standard PCB material reveals that only the input bias current (IB) parameter is impacted when the package is illuminated directly by high intensity light. No degradation in electrical performance is observed due to illumination by low intensity (0.1 mW/cm2) ambient light. Figure 50 shows that IB increases with increasing wavelength and intensity of incident light; IB can reach levels as high as 4500 pA at a light intensity of 3 mW/cm2 and a wavelength of 850 nm. The light intensities 2mW/cm2 2000 1500 1000 500 0 350 450 550 650 WAVELENGTH (nm) 750 850 02731-D-050 1mW/cm2 Figure 50. AD8605ACB Input Bias Current Response to Direct Illumination of Varying Intensity and Wavelength MICROCSP ASSEMBLY CONSIDERATIONS For detailed information on MicroCSP PCB assembly and reliability, refer to ADI Application Note AN-617 on the ADI website www.analog.com. Rev. D | Page 15 of 20 AD8605/AD8606/AD8608 I-V CONVERSION APPLICATIONS PHOTODIODE PREAMPLIFIER APPLICATIONS The low offset voltage and input current of the AD8605 make it an excellent choice for photodiode applications. In addition, the low voltage and current noise make the amplifier ideal for application circuits with high sensitivity. CF 10pF RF 10M At room temperature, the AD8605 has an input bias current of 0.2 pA and an offset voltage of 100 V. Typical values of RD are in the range of 1 G. For the circuit shown in Figure 9, the output error voltage is approximately 100 V at room temperature, increasing to about 1 mV at 85C. Where ft is the unity gain frequency of the amplifier, the maximum achievable signal bandwidth is PHOTODIODE +VOS- CD 50pF f MAX = AD8605 VOUT 02731-D-051 ft 2RF CT RD ID AUDIO AND PDA APPLICATIONS The AD8605's low distortion and wide dynamic range make it a great choice for audio and PDA applications, including microphone amplification and line output buffering. Figure 52 shows a typical application circuit for headphone/line out amplification. R1 and R2 are used to bias the input voltage at half the supply. This maximizes the signal bandwidth range. C1 and C2 are used to ac couple the input signal. C1 and R2 form a high-pass filter whose corner frequency is 1/2R1C1. The high output current of the AD8605 allows it to drive heavy resistive loads. The circuit of Figure 52 was tested to drive a 16 W headphone. The THD + N is maintained at approximately -60 dB throughout the audio range. 5V Figure 51. Equivalent Circuit for Photodiode Preamp The input bias current of the amplifier contributes an error term that is proportional to the value of RF. The offset voltage causes a dark current induced by the shunt resistance of the diode RD. These error terms are combined at the output of the amplifier. The error voltage is written as R EO = VOS 1 + F + RF I B R D Typically, RF is smaller than RD, thus RF/RD can be ignored. C1 1F R1 10k R2 10k 3 8 V1 500mV 1/2 AD8606 4 C3 100F 1 R4 20 R3 HEADPHONES 1k 2 5V C2 1F 5 V2 500mV 6 8 1/2 AD8606 4 C4 100F 7 R6 20 Figure 52. Single-Supply Headphone/Speaker Amplifier Rev. D | Page 16 of 20 02731-D-052 R5 1k AD8605/AD8606/AD8608 INSTRUMENTATION AMPLIFIERS The low offset voltage and low noise of the AD8605 make it a great amplifier for instrumentation applications. Difference amplifiers are widely used in high accuracy circuits to improve the common-mode rejection ratio. Figure 53 shows a simple difference amplifier. The CMRR of the circuit is plotted versus frequency. Figure 54 shows the common-mode rejection for a unity gain configuration and for a gain of 10. Making (R4/R3) = (R2/R1) and choosing 0.01% tolerance yields a CMRR of 74 dB and minimizes the gain error at the output. R1 1k 5V R4 R2 = R3 R1 VOUT = R2 (V2 - V1) R1 R2 10k VREF R R R CF RF R2 R2 R2 VOS V+ AD8605 02731-D-055 V- Figure 55. Simplified Circuit of the DAC8143 with AD8605 Output Buffer V1 AD8605 VOUT To optimize the performance of the DAC, insert a capacitor in the feedback loop of the AD8605 to compensate the amplifier from the pole introduced by the output capacitance of the DAC. Typical values for CF are in the range of 10 pF to 30 pF; it can be adjusted for the best frequency response. The total error at the output of the op amp can be computed by the formula: R EO = VOS 1 + F Re q V2 02731-D-053 R3 1k R4 10k Figure 53. Difference Amplifier, AV = 10 120 VSY = 2.5V 100 AV = 10 where Req is the equivalent resistance seen at the output of the DAC. As mentioned above, Req is code dependant and varies with the input. A typical value for Req is 15 k. Choosing a feedback resistor of 10 k yields an error of less than 200 V. Figure 56 shows the implementation of a dual-stage buffer at the output of a DAC. The first stage is used as a buffer. Capacitor C1, with Req, creates a low-pass filter and thus provides phase lead to compensate for frequency response. The second stage of the AD8606 is used to provide voltage gain at the output of the buffer. Grounding the positive input terminals in both stages reduces errors due to the common-mode output voltage. Choosing R1, R2, and R3 to match within 0.01% yields a CMRR of 74 dB and maintains minimum gain error in the circuit. RCS C1 33pF VDD VREF RFB OUT1 AGND DB11 R1 10k R3 20k R2 10k 80 AV = 1 CMRR (dB) 60 40 0 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 02731-D-054 20 Figure 54. Difference Amplifier CMRR vs. Frequency 15V D/A CONVERSION The low input bias current and offset voltage of the AD8605 make it an excellent choice for buffering the output of a current output DAC. Figure 55 shows a typical implementation of the AD8605 at the output of a 12-bit DAC. The DAC8143 output current is converted to a voltage by the feedback resistor. The equivalent resistance at the output of the DAC varies with the input code, as does the output capacitance. Rev. D | Page 17 of 20 AD7545 VOUT VIN RP 1/2 AD8606 R4 5k10% Figure 56. Bipolar Operation 02731-D-056 1/2 AD8606 AD8605/AD8606/AD8608 OUTLINE DIMENSIONS 2.90 BSC 5.00 (0.1968) 4.80 (0.1890) 4 8 5 4 5 1.60 BSC 1 2 3 2.80 BSC 4.00 (0.1574) 3.80 (0.1497) 1 6.20 (0.2440) 5.80 (0.2284) PIN 1 0.95 BSC 1.30 1.15 0.90 1.90 BSC 0.25 (0.0098) 0.10 (0.0040) 1.27 (0.0500) BSC 1.75 (0.0688) 1.35 (0.0532) 0.50 (0.0196) x 45 0.25 (0.0099) 1.45 MAX 0.22 0.08 10 5 0 0.60 0.45 0.30 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) 0.15 MAX 0.50 0.30 SEATING PLANE 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 COMPLIANT TO JEDEC STANDARDS MO-178AA Figure 57. 5-Lead Small Outline Transistor Package [SOT-23] (RT-5) 8.75 (0.3445) 8.55 (0.3366) 14 1 8 7 Figure 60. 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) 5.10 5.00 4.90 4.00 (0.1575) 3.80 (0.1496) 6.20 (0.2441) 5.80 (0.2283) 4.50 4.40 4.30 14 8 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10 1.27 (0.0500) BSC 1.75 (0.0689) 1.35 (0.0531) 0.50 (0.0197) x 45 0.25 (0.0098) 6.40 BSC 1 7 0.51 (0.0201) 0.31 (0.0122) SEATING PLANE 8 0.25 (0.0098) 0 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) PIN 1 1.05 1.00 0.80 0.65 BSC 1.20 MAX 0.15 0.05 0.30 0.19 0.20 0.09 8 0 0.75 0.60 0.45 COMPLIANT TO JEDEC STANDARDS MS-012AB 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 SEATING COPLANARITY PLANE 0.10 COMPLIANT TO JEDEC STANDARDS MO-153AB-1 Figure 58. 14-Lead Standard Small Outline Package [SOIC] Narrow Body (R-14) 3.00 BSC Figure 61. 14-Lead Thin Shrink Small Outline Package [TSSOP] (RU-14) 8 5 3.00 BSC 4 4.90 BSC PIN 1 IDENTIFIER 0.94 0.90 0.86 0.50 REF 0.37 0.36 0.35 SEATING PLANE 0.87 BOTTOM VIEW PIN 1 0.65 BSC 1.10 MAX 8 0 0.80 0.60 0.40 TOP VIEW (BALL SIDE DOWN) 1.33 1.29 1.25 0.23 0.18 0.14 0.21 0.50 0.15 0.00 0.38 0.22 COPLANARITY 0.10 0.23 0.08 SEATING PLANE 0.17 0.14 0.12 0.20 0.50 COMPLIANT TO JEDEC STANDARDS MO-187AA Figure 59. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Figure 62. 5-Bump 2 x 1 x 2 Array MicroCSP [WLCSP] (CB-5) Rev. D | Page 18 of 20 AD8605/AD8606/AD8608 ORDERING GUIDE Model AD8605ACB-REEL AD8605ACB-REEL7 AD8605ART-R2 AD8605ART-REEL AD8605ART-REEL7 AD8605ARTZ-REEL1 AD8605ARTZ-REEL71 AD8606ARM-R2 AD8606ARM-REEL AD8606AR AD8606AR-REEL AD8606AR-REEL7 AD8608AR AD8608AR-REEL AD8608AR-REEL7 AD8608ARU AD8608ARU-REEL Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C Package Description 5-Bump MicroCSP 5-Bump MicroCSP 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 14-Lead SOIC 14-Lead SOIC 14-Lead SOIC 14-Lead TSSOP 14-Lead TSSOP Package Option CB-5 CB-5 RT-5 RT-5 RT-5 RT-5 RT-5 RM-8 RM-8 R-8 R-8 R-8 R-14 R-14 R-14 RU-14 RU-14 Branding B3A B3A B3A B3A B3A B3A B3A B6A B6A 1 Z = Pb-free part. Rev. D | Page 19 of 20 AD8605/AD8606/AD8608 NOTES (c) 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C02731-0-5/04(D) Rev. D | Page 20 of 20 |
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