Precision, 20 MHz, CMOS, Rail-to-Rail Input/Output Operational Amplifiers AD8615/AD8616/AD8618 Barcode scanners Battery-powered instrumentation Multipole filters Sensors ASIC input or output amplifiers Audio Photodiode amplification GENERAL DESCRIPTION The AD8615/AD8616/AD8618 are single/dual/quad, rail-torail, input and output, single-supply amplifiers featuring very low offset voltage, wide signal bandwidth, and low input voltage and current noise. The parts use a patented trimming technique that achieves superior precision without laser trimming. The AD8615/AD8616/ AD8618 are fully specified to operate from 2.7 V to 5 V single supplies. The combination of >20 MHz bandwidth, low offset, low noise, and low input bias current 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. AC applications benefit from the wide bandwidth and low distortion. The AD8615/AD8616/ AD8618 offer the highest output drive capability of the DigiTrim® family, which is excellent for audio line drivers and other low impedance applications. Applications for the parts include portable and low powered instrumentation, audio amplification for portable devices, portable phone headsets, bar code scanners, and multipole filters. The ability to swing rail-to-rail at both the input and output enables designers to buffer CMOS ADCs, DACs, ASICs, and other wide output swing devices in single-supply systems. OUT 1 5 V+ 4 –IN AD8615 +IN 3 TOP VIEW (Not to Scale) 04648-001 V– 2 OUT A 1 –IN A 2 +IN A 3 AD8616 TOP VIEW V– 4 (Not to Scale) 8 V+ 7 OUT B 6 –IN B 5 +IN B 04648-002 Figure 1. 5-Lead TSOT-23 (UJ-5) Figure 2. 8-Lead MSOP (RM-8) OUT A 1 –IN A 2 +IN A 3 AD8616 TOP VIEW V– 4 (Not to Scale) 8 V+ 7 OUT B 6 –IN B 5 +IN B 04648-003 APPLICATIONS PIN CONFIGURATIONS Figure 3. 8-Lead SOIC (R-8) OUT A –IN A +IN A V+ +IN B –IN B OUT B 1 OUT D –IN D +IN D V– +IN C –IN C OUT C 14 AD8618 TOP VIEW (Not to Scale) 7 8 04648-004 Low offset voltage: 65 μV maximum Single-supply operation: 2.7 V to 5.0 V Low noise: 8 nV/√Hz Wide bandwidth: >20 MHz Slew rate: 12 V/μs High output current: 150 mA No phase reversal Low input bias current: 1 pA Low supply current: 2 mA Unity-gain stable Figure 4. 14-Lead TSSOP (RU-14) OUT A 1 14 OUT D –IN A 2 13 –IN D 12 +IN D +IN A 3 AD8618 V+ 4 11 V– TOP VIEW +IN B 5 (Not to Scale) 10 +IN C –IN B 6 9 –IN C OUT B 7 8 OUT C 04648-005 FEATURES Figure 5. 14-Lead SOIC (R-14) The AD8615/AD8616/AD8618 are specified over the extended industrial temperature range (−40°C to +125°C). The AD8615 is available in 5-lead TSOT-23 package. The AD8616 is available in 8-lead MSOP and narrow SOIC surface-mount packages; the MSOP version is available in tape and reel only. The AD8618 is available in 14-lead SOIC and TSSOP packages. Rev. E 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: 781.461.3113 ©2004–2008 Analog Devices, Inc. All rights reserved. AD8615/AD8616/AD8618 TABLE OF CONTENTS Features .............................................................................................. 1 Output Phase Reversal ............................................................... 11 Applications ....................................................................................... 1 Driving Capacitive Loads .......................................................... 11 General Description ......................................................................... 1 Overload Recovery Time .......................................................... 12 Pin Configurations ........................................................................... 1 D/A Conversion ......................................................................... 12 Revision History ............................................................................... 2 Low Noise Applications ............................................................. 12 Specifications..................................................................................... 3 High Speed Photodiode Preamplifier ...................................... 13 Absolute Maximum Ratings............................................................ 5 Active Filters ............................................................................... 13 Thermal Resistance ...................................................................... 5 Power Dissipation....................................................................... 13 ESD Caution .................................................................................. 5 Power Calculations for Varying or Unknown Loads............. 14 Typical Performance Characteristics ............................................. 6 Outline Dimensions ....................................................................... 15 Applications Information .............................................................. 11 Ordering Guide .......................................................................... 17 Input Overvoltage Protection ................................................... 11 REVISION HISTORY 9/08—Rev. D to Rev. E Changes to General Description Section ...................................... 1 Updated Outline Dimensions ....................................................... 15 Changes to Ordering Guide .......................................................... 17 4/04—Rev. 0 to Rev. A Added AD8618 ................................................................... Universal Updated Outline Dimensions ....................................................... 16 1/04—Revision 0: Initial Version 5/08—Rev. C to Rev. D Changes to Layout ............................................................................ 1 Changes to Figure 38 ...................................................................... 11 Changes to Figure 44 and Figure 45 ............................................. 13 Changes to Layout .......................................................................... 15 Changes to Layout .......................................................................... 16 6/05—Rev. B to Rev. C Change to Table 1 ............................................................................. 3 Change to Table 2 ............................................................................. 4 Change to Figure 20 ......................................................................... 8 1/05—Rev. A to Rev. B Added AD8615 ................................................................... Universal Changes to Figure 12 ........................................................................ 8 Deleted Figure 19; Renumbered Subsequently ............................. 8 Changes to Figure 20 ........................................................................ 9 Changes to Figure 29 ...................................................................... 10 Changes to Figure 31 ...................................................................... 11 Deleted Figure 34; Renumbered Subsequently ........................... 11 Deleted Figure 35; Renumbered Subsequently ........................... 35 Rev. E | Page 2 of 20 AD8615/AD8616/AD8618 SPECIFICATIONS VS =5 V, VCM = VS/2, TA = 25°C, unless otherwise noted. Table 1. Parameter INPUT CHARACTERISTICS Offset Voltage, AD8616/AD8618 Offset Voltage, AD8615 Offset Voltage Drift, AD8616/AD8618 Offset Voltage Drift, AD8615 Input Bias Current Symbol Conditions VOS VS = 3.5 V at VCM = 0.5 V and 3.0 V ∆VOS/∆T VCM = 0 V to 5 V −40°C < TA < +125°C −40°C < TA < +125°C Min Typ Max Unit 23 23 80 60 100 500 800 7 10 1 50 550 0.5 50 250 5 μV μV μV μV μV/°C μV/°C pA pA pA pA pA pA V dB V/mV pF pF 1.5 3 0.2 IB −40°C < TA < +85°C −40°C < TA < +125°C Input Offset Current IOS 0.1 −40°C < TA < +85°C −40°C < TA < +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Input Capacitance OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current Closed-Loop Output Impedance POWER SUPPLY Power Supply Rejection Ratio Supply Current per Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Current Noise Density Channel Separation CMRR AVO CDIFF CCM VCM = 0 V to 4.5 V RL = 2 kΩ, VO = 0.5 V to 5 V VOH IL = 1 mA IL = 10 mA −40°C < TA < +125°C IL = 1 mA IL = 10 mA −40°C < TA < +125°C VOL IOUT ZOUT 0 80 105 4.98 4.88 4.7 100 1500 2.5 6.7 4.99 4.92 7.5 70 15 100 200 ±150 3 f = 1 MHz, AV = 1 PSRR ISY VS = 2.7 V to 5.5 V VO = 0 V −40°C < TA < +125°C SR tS GBP Øm RL = 2 kΩ To 0.01% 12 <0.5 24 63 V/μs μs MHz Degrees en p-p en 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 1 kHz f = 10 kHz f = 100 kHz 2.4 10 7 0.05 −115 −110 μV nV/√Hz nV/√Hz pA/√Hz dB dB in CS Rev. E | Page 3 of 20 70 90 1.7 V V V mV mV mV mA Ω 2 2.5 dB mA mA AD8615/AD8616/AD8618 VS = 2.7 V, VCM = VS/2, TA = 25°C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage, AD8616/AD8618 Offset Voltage, AD8615 Offset Voltage Drift, AD8616/AD8618 Offset Voltage Drift, AD8615 Input Bias Current Symbol Conditions VOS VS = 3.5 V at VCM = 0.5 V and 3.0 V ∆VOS/∆T VCM = 0 V to 2.7 V −40°C < TA < +125°C −40°C < TA < +125°C Min Typ Max Unit 23 23 80 65 100 500 800 7 10 1 50 550 0.5 50 250 2.7 μV μV μV μV μV/°C μV/°C pA pA pA pA pA pA V dB V/mV pF pF 1.5 3 0.2 IB −40°C < TA < +85°C −40°C < TA < +125°C Input Offset Current IOS 0.1 −40°C < TA < +85°C −40°C < TA < +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Input Capacitance OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Output Current Closed-Loop Output Impedance POWER SUPPLY Power Supply Rejection Ratio Supply Current per Amplifier DYNAMIC PERFORMANCE Slew Rate Settling Time Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Peak-to-Peak Noise Voltage Noise Density Current Noise Density Channel Separation CMRR AVO CDIFF CCM VCM = 0 V to 2.7 V RL = 2 kΩ, VO = 0.5 V to 2.2 V VOH IL = 1 mA −40°C < TA < +125°C IL = 1 mA −40°C < TA < +125°C VOL IOUT ZOUT 0 80 55 2.65 2.6 100 150 2.5 7.8 2.68 11 25 30 ±50 3 f = 1 MHz, AV = 1 PSRR ISY VS = 2.7 V to 5.5 V VO = 0 V −40°C < TA < +125°C SR tS GBP Øm RL = 2 kΩ To 0.01% 12 <0.3 23 42 V/μs μs MHz Degrees en p-p en 0.1 Hz to 10 Hz f = 1 kHz f = 10 kHz f = 1 kHz f = 10 kHz f = 100 kHz 2.1 10 7 0.05 −115 −110 μV nV/√Hz nV/√Hz pA/√Hz dB dB in CS Rev. E | Page 4 of 20 70 90 1.7 V V mV mV mA Ω 2 2.5 dB mA mA AD8615/AD8616/AD8618 ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 3. Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration to GND Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 60 sec) Junction Temperature Rating 6V GND to VS ±3 V Indefinite −65°C to +150°C −40°C to +125°C 300°C 150°C 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 indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. θJA is specified for the worst-case conditions, that is, θJA is specified for a device soldered in a circuit board for surface-mount packages. Table 4. Package Type 5-Lead TSOT-23 (UJ) 8-Lead MSOP (RM) 8-Lead SOIC (R) 14-Lead SOIC (R) 14-Lead TSSOP (RU) ESD CAUTION Rev. E | Page 5 of 20 θJA 207 210 158 120 180 θJC 61 45 43 36 35 Unit °C/W °C/W °C/W °C/W °C/W AD8615/AD8616/AD8618 TYPICAL PERFORMANCE CHARACTERISTICS 2200 350 VS = 5V TA = 25°C VCM = 0V TO 5V 2000 INPUT BIAS CURRENT (pA) NUMBER OF AMPLIFIERS 1800 VS = ±2.5V 300 1600 1400 1200 1000 800 600 250 200 150 100 400 50 –700 –500 –300 –100 100 300 500 700 OFFSET VOLTAGE (µV) 0 04648-006 0 0 25 22 1000 125 100 16 14 VSY – VOUT (mV) NUMBER OF AMPLIFIERS 100 VS = 5V TA = 25°C VS = ±2.5V TA = –40°C TO +125°C VCM = 0V 18 75 Figure 9. Input Bias Current vs. Temperature Figure 6. Input Offset Voltage Distribution 20 50 TEMPERATURE (-°C) 04648-009 200 12 10 8 6 10 SOURCE SINK 1 4 0 2 4 6 8 10 12 0.1 0.001 04648-007 0 TCVOS (µV/°C) 500 100 120 VS = 5V TA = 25°C VS = 5V 300 200 100 0 –100 –200 –300 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 COMMON-MODE VOLTAGE (V) 5.0 04648-008 –400 Figure 8. Input Offset Voltage vs. Common-Mode Voltage (200 Units, Five Wafer Lots Including Process Skews) 100 10mA LOAD 80 60 40 20 1mA LOAD 0 –40 –25 –10 5 20 35 50 65 80 95 110 TEMPERATURE (°C) Figure 11. Output Saturation Voltage vs. Temperature Rev. E | Page 6 of 20 125 04648-011 OUTPUT SATURATION VOLTAGE (mV) 400 INPUT OFFSET VOLTAGE (µV) 10 Figure 10. Output Voltage to Supply Rail vs. Load Current Figure 7. Offset Voltage Drift Distribution –500 1 0.1 ILOAD (mA) 0.01 04648-010 2 AD8615/AD8616/AD8618 100 135 90 20 45 0 0 –20 –45 –40 –90 –60 –135 –80 –180 –100 1M 80 CMRR (dB) 40 PHASE (Degrees) 60 VS = ±2.5V 180 40 20 –225 60M 10M FREQUENCY (Hz) 60 0 04648-012 80 1k 10k 1M 10M Figure 15. CMRR vs. Frequency Figure 12. Open-Loop Gain and Phase vs. Frequency 120 5.0 VS = ±2.5V VS = 5.0V VIN = 4.9V p-p TA = 25°C RL = 2kΩ AV = 1 4.5 4.0 3.5 100 80 3.0 PSRR (dB) OUTPUT SWING (V p-p) 100k FREQUENCY (Hz) 2.5 2.0 60 40 1.5 1.0 20 10k 100k 1M 10M FREQUENCY (Hz) 04648-013 1k 1k 10k 1000 50 VS = ±2.5V SMALL-SIGNAL OVERSHOOT (%) 70 60 50 40 30 AV = 100 20 AV = 1 AV = 10 10 10k VS = 5V RL = ∞ TA = 25°C AV = 1 45 80 OUTPUT IMPEDANCE (Ω) 10M Figure 16. PSRR vs. Frequency 100 0 1k 1M FREQUENCY (Hz) Figure 13. Closed-Loop Output Voltage Swing vs. Frequency 90 100k 04648-016 0 0 04648-017 0.5 100k 40 35 30 25 20 15 –OS 10 +OS 5 1M 10M FREQUENCY (Hz) 100M 04648-014 GAIN (dB) 120 225 VS = ±2.5V TA = 25°C Øm = 63° 04648-015 100 0 10 100 CAPACITANCE (pF) Figure 17. Small-Signal Overshoot vs. Load Capacitance Figure 14. Output Impedance vs. Frequency Rev. E | Page 7 of 20 AD8615/AD8616/AD8618 VS = 5V RL = 10kΩ CL = 200pF AV = 1 2.2 2.0 VS = 2.7V 1.8 VOLTAGE (50mV/DIV) VS = 5V 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TIME (1µs/DIV) Figure 21. Small Signal Transient Response Figure 18. Supply Current vs. Temperature VS = 5V RL = 10kΩ CL = 200pF AV = 1 1800 VOLTAGE (500mV/DIV) 1600 1400 1200 1000 800 600 400 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) 04648-022 200 04648-019 TIME (1s/DIV) Figure 22. Large Signal Transient Response Figure 19. Supply Current per Amplifier vs. Supply Voltage 0.1 1k VS = ±2.5V VS = ±1.35V VS = ±2.5V VIN = 0.5V rms AV = 1 BW = 22kHz RL = 100kΩ 0.01 THD+N (%) 100 0.001 1 10 100 1k FREQUENCY (Hz) 10k 100k 04648-020 10 0.0001 20 100 1k FREQUENCY (Hz) Figure 23. THD + N vs. Frequency Figure 20. Voltage Noise Density vs. Frequency Rev. E | Page 8 of 20 20k 04648-023 SUPPLY CURRENT PER AMPLIFIER (µA) 2000 VOLTAGE NOISE DENSITY (nV/ Hz 0.5) 04648-021 0.2 04648-018 SUPPLY CURRENT PER AMPLIFIER (mA) 2.4 AD8615/AD8616/AD8618 500 VS = ±2.5V VIN = 2V p-p AV = 10 VS = 2.7V TA = 25°C VOLTAGE (2V/DIV) INPUT OFFSET VOLTAGE (µV) 400 300 200 100 0 –100 –200 –300 –400 TIME (200ns/DIV) 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 COMMON-MODE VOLTAGE (V) Figure 24. Settling Time 04648-027 04648-024 –500 Figure 27. Input Offset Voltage vs. Common-Mode Voltage (200 Units, Five Wafer Lots Including Process Skews) 500 VS = 2.7V VS = 3.5V TA = 25°C VOLTAGE (1µV/DIV) INPUT OFFSET VOLTAGE (µV) 400 300 200 100 0 –100 –200 –300 04648-025 –500 TIME (1s/DIV) 1.0 1.5 2.0 2.5 3.0 3.5 COMMON-MODE VOLTAGE (V) 1000 1400 VS = 2.7V TA = 25°C VCM = 0V TO 2.7V VS = ±1.35V TA = 25°C 100 VSY – VOUT (mV) 1000 800 600 10 SOURCE SINK 400 1 0 –700 –500 –300 –100 100 300 500 700 OFFSET VOLTAGE (µV) 0.1 0.001 0.01 0.1 ILOAD (mA) 1 Figure 29. Output Voltage to Supply Rail vs. Load Current Figure 26. Input Offset Voltage Distribution Rev. E | Page 9 of 20 10 04648-029 200 04648-026 NUMBER OF AMPLIFIERS 0.5 Figure 28. Input Offset Voltage vs. Common-Mode Voltage (200 Units, Five Wafer Lots Including Process Skews) Figure 25. 0.1 Hz to 10 Hz Input Voltage Noise 1200 0 04648-028 –400 AD8615/AD8616/AD8618 18 SMALL SIGNAL OVERSHOOT (%) VOH @ 1mA LOAD 14 12 10 VOL @ 1mA LOAD 8 6 4 2 20 35 50 65 80 95 110 100 125 15 10 1000 VS = 2.7V RL = 10kΩ CL = 200pF AV = 1 20 45 0 0 –20 –45 –40 –90 –60 –135 –80 –180 –225 60M PHASE (Degrees) 90 VOLTAGE (50mV/DIV) 135 10M FREQUENCY (Hz) 100 04648-031 TIME (1µs/DIV) Figure 34. Small Signal Transient Response Figure 31. Open-Loop Gain and Phase vs. Frequency 2.7 VS = 2.7V RL = 10kΩ CL = 200pF AV = 1 VOLTAGE (500mV/DIV) VS = 2.7V VIN = 2.6V p-p TA = 25°C RL = 2kΩ AV = 1 1.5 1.2 0.9 0.6 0 1k 10k 100k 1M 10M FREQUENCY (Hz) 04648-032 0.3 Figure 32. Closed-Loop Output Voltage Swing vs. Frequency TIME (1µs/DIV) Figure 35. Large Signal Transient Response Rev. E | Page 10 of 20 04648-035 GAIN (dB) +OS CAPACITANCE (pF) 180 –100 1M OUTPUT SWING (V p-p) –OS 20 Figure 33. Small Signal Overshoot vs. Load Capacitance 40 1.8 25 10 225 VS = ±1.35V TA = 25°C Øm = 42° 2.1 30 04648-033 5 04648-030 –10 Figure 30. Output Saturation Voltage vs. Temperature 2.4 35 0 –25 TEMPERATURE (°C) 60 40 5 0 –40 80 VS = ±1.35V RL = ∞ TA = 25°C AV = 1 45 04648-034 OUTPUT SATURATION VOLTAGE (mV) 16 50 VS = 2.7V AD8615/AD8616/AD8618 APPLICATIONS INFORMATION The AD8615/AD8616/AD8618 have internal protective circuitry that allows voltages exceeding the supply to be applied at the input. It is recommended, however, not to apply voltages that exceed the supplies by more than 1.5 V at either input of the amplifier. If a higher input voltage is applied, series resistors should be used to limit the current flowing into the inputs. The input current should be limited to <5 mA. The extremely low input bias current allows the use of larger resistors, which allows the user to apply higher voltages at the inputs. The use of these resistors adds thermal noise, which contributes to the overall output voltage noise of the amplifier. This reduces the overshoot and minimizes ringing, which in turn improves the frequency response of the AD8615/AD8616/ AD8618. One simple technique for compensation is the snubber, which consists of a simple RC network. With this circuit in place, output swing is maintained and the amplifier is stable at all gains. Figure 38 shows the implementation of the snubber, which reduces overshoot by more than 30% and eliminates ringing that can cause instability. Using the snubber does not recover the loss of bandwidth incurred from a heavy capacitive load. VS = ±2.5V AV = 1 CL = 500pF VOLTAGE (100mV/DIV) INPUT OVERVOLTAGE PROTECTION For example, a 10 kΩ resistor has less than 13 nV/√Hz of thermal noise and less than 10 nV of error voltage at room temperature. OUTPUT PHASE REVERSAL Phase reversal can cause permanent damage to the amplifier and can create lock ups in systems with feedback loops. 04648-037 The AD8615/AD8616/AD8618 are immune to phase inversion, a phenomenon that occurs when the voltage applied at the input of the amplifier exceeds the maximum input common mode. TIME (2µs/DIV) Figure 37. Driving Heavy Capacitive Loads Without Compensation VEE + – VOUT V– V+ 200Ω VIN – 200mV VCC 500pF 500pF 04648-038 VOLTAGE (2V/DIV) VS = ±2.5V VIN = 6V p-p AV = 1 RL = 10kΩ VOLTAGE (100mV/DIV) Figure 36. No Phase Reversal DRIVING CAPACITIVE LOADS Although the AD8615/AD8616/AD8618 are capable of driving capacitive loads of up to 500 pF without oscillating, a large amount of overshoot is present when operating at frequencies above 100 kHz. This is especially true when the amplifier is configured in positive unity gain (worst case). When such large capacitive loads are required, the use of external compensation is highly recommended. VS = ±2.5V AV = 1 RS = 200Ω CS = 500pF CL = 500pF TIME (10µs/DIV) 04648-039 TIME (2ms/DIV) 04648-036 Figure 38. Snubber Network Figure 39. Driving Heavy Capacitive Loads Using the Snubber Network Rev. E | Page 11 of 20 AD8615/AD8616/AD8618 5V OVERLOAD RECOVERY TIME VDD REFF 1/2 AD8616 DIN SCLK AD5542 VOUT UNIPOLAR OUTPUT LDAC DGND AGND Figure 42. Buffering DAC Output Although the AD8618 typically has less than 8 nV/√Hz of voltage noise density at 1 kHz, it is possible to reduce it further. A simple method is to connect the amplifiers in parallel, as shown in Figure 43. The total noise at the output is divided by the square root of the number of amplifiers. In this case, the total noise is approximately 4 nV/√Hz at room temperature. The 100 Ω resistor limits the current and provides an effective output resistance of 50 Ω. 0V 0V 3 VIN –50mV V+ 04648-040 R1 TIME (1µs/DIV) REFS CS LOW NOISE APPLICATIONS VS = ±2.5V RL = 10kΩ AV = 100 VIN = 50mV +2.5V 0.1µF 0.1µF SERIAL INTERFACE 10µF + 04648-042 Overload recovery time is the time it takes the output of the amplifier to come out of saturation and recover to its linear region. Overload recovery is particularly important in applications where small signals must be amplified in the presence of large transients. Figure 40 and Figure 41 show the positive and negative overload recovery times of the AD8616. In both cases, the time elapsed before the AD8616 comes out of saturation is less than 1 μs. In addition, the symmetry between the positive and negative recovery times allows excellent signal rectification without distortion to the output signal. 2.5V 2 1 V– R3 100Ω 10Ω R2 Figure 40. Positive Overload Recovery 1kΩ 3 V+ VS = ±2.5V RL = 10kΩ AV = 100 VIN = 50mV R4 2 1 V– R6 100Ω 10Ω R5 –2.5V 0V VOUT 1kΩ 3 0V V+ R7 2 1 V– R9 100Ω 10Ω R8 1kΩ +50mV V+ R10 2 1 V– R12 100Ω 10Ω Figure 41. Negative Overload Recovery R11 D/A CONVERSION The AD8616 can be used at the output of high resolution DACs. The low offset voltage, fast slew rate, and fast settling time make the part suitable to buffer voltage output or current output DACs. Figure 42 shows an example of the AD8616 at the output of the AD5542. The AD8616’s rail-to-rail output and low distortion help maintain the accuracy needed in data acquisition systems and automated test equipment. Rev. E | Page 12 of 20 1kΩ Figure 43. Noise Reduction 04648-043 TIME (1µs/DIV) 04648-041 3 AD8615/AD8616/AD8618 10 HIGH SPEED PHOTODIODE PREAMPLIFIER The total input capacitance, C1, is the sum of the diode and op amp input capacitances. This creates a feedback pole that causes degradation of the phase margin, making the op amp unstable. Therefore, it is necessary to use a capacitor in the feedback to compensate for this pole. To get the maximum signal bandwidth, select C2 –2.5V CIN + V– V+ +2.5V –VBIAS 1 10 100 1k 10k 100k 1M FREQUENCY (Hz) Figure 46. Second-Order Butterworth, Low-Pass Filter Frequency Response 04648-044 – CD –40 0.1 In any application, the absolute maximum junction temperature for the AD8615/AD8616/AD8618 is 150°C. This should never be exceeded because the device could suffer premature failure. Accurately measuring power dissipation of an integrated circuit is not always a straightforward exercise; Figure 47 is a design aid for setting a safe output current drive level or selecting a heat sink for the package options available on the AD8616. R2 RSH –30 Although the AD8615/AD8616/AD8618 are capable of providing load currents up to 150 mA, the usable output, load current, and drive capability are limited to the maximum power dissipation allowed by the device package. where fU is the unity-gain bandwidth of the amplifier. ID –20 POWER DISSIPATION C1 2πR 2 f U C2 = –10 04648-046 In high speed photodiode applications, the diode is operated in a photoconductive mode (reverse biased). This lowers the junction capacitance at the expense of an increase in the amount of dark current that flows out of the diode. 0 GAIN (dB) The AD8615/AD8616/AD8618 are excellent choices for I-to-V conversions. The very low input bias, low current noise, and high unity-gain bandwidth of the parts make them suitable, especially for high speed photodiode preamplifiers. 1.5 ACTIVE FILTERS The low input bias current and high unity-gain bandwidth of the AD8616 make it an excellent choice for precision filter design. Figure 45 shows the implementation of a second-order, low-pass filter. The Butterworth response has a corner frequency of 100 kHz and a phase shift of 90°. The frequency response is shown in Figure 46. POWER DISSIPATION (W) Figure 44. High Speed Photodiode Preamplifier 1.0 SOIC MSOP 0.5 0 VEE 1nF V+ VCC 04648-045 VIN 1.1kΩ 20 40 60 80 100 TEMPERATURE (°C) 120 140 Figure 47. Maximum Power Dissipation vs. Ambient Temperature V– 1.1kΩ 0 These thermal resistance curves were determined using the AD8616 thermal resistance data for each package and a maximum junction temperature of 150°C. Figure 45. Second-Order, Low-Pass Filter Rev. E | Page 13 of 20 04648-047 2nF AD8615/AD8616/AD8618 The following formula can be used to calculate the internal junction temperature of the AD8615/AD8616/AD8618 for any application: Calculating Power by Measuring Ambient Temperature and Case Temperature The two equations for calculating the junction temperature are TJ = PDISS × θJA + TA TJ = TA + P θJA where: TJ = junction temperature PDISS = power dissipation θJA = package thermal resistance, junction-to-case TA = ambient temperature of the circuit where: TJ = junction temperature TA = ambient temperature θJA = the junction-to-ambient thermal resistance TJ = TC + P θJC To calculate the power dissipated by the AD8615/AD8616/ AD8618, use the following: where: TC is case temperature. θJA and θJC are given in the data sheet. PDISS = ILOAD × (VS – VOUT) where: ILOAD = output load current VS = supply voltage VOUT = output voltage The two equations for calculating P (power) are The quantity within the parentheses is the maximum voltage developed across either output transistor. Once the power is determined, it is necessary to recalculate the junction temperature to ensure that the temperature was not exceeded. TA + P θJA = TC + P θJC P = (TA − TC)/(θJC − θJA) POWER CALCULATIONS FOR VARYING OR UNKNOWN LOADS Often, calculating power dissipated by an integrated circuit to determine if the device is being operated in a safe range is not as simple as it may seem. In many cases, power cannot be directly measured. This may be the result of irregular output waveforms or varying loads. Indirect methods of measuring power are required. There are two methods to calculate power dissipated by an integrated circuit. The first is to measure the package temperature and the board temperature. The second is to directly measure the circuit’s supply current. The temperature should be measured directly on and near the package but not touching it. Measuring the package can be difficult. A very small bimetallic junction glued to the package can be used, or an infrared sensing device can be used, if the spot size is small enough. Calculating Power by Measuring Supply Current If the supply voltage and current are known, power can be calculated directly. However, the supply current can have a dc component with a pulse directed into a capacitive load, which can make the rms current very difficult to calculate. This difficulty can be overcome by lifting the supply pin and inserting an rms current meter into the circuit. For this method to work, make sure the current is delivered by the supply pin being measured. This is usually a good method in a single-supply system; however, if the system uses dual supplies, both supplies may need to be monitored. Rev. E | Page 14 of 20 AD8615/AD8616/AD8618 OUTLINE DIMENSIONS 2.90 BSC 5 4 2.80 BSC 1.60 BSC 1 2 3 0.95 BSC 1.90 BSC *0.90 MAX 0.70 NOM 0.10 MAX 0.50 0.30 0.20 0.08 8° 4° 0° SEATING PLANE 0.60 0.45 0.30 091508-A *1.00 MAX *COMPLIANT TO JEDEC STANDARDS MO-193-AB WITH THE EXCEPTION OF PACKAGE HEIGHT AND THICKNESS. Figure 48. 5-Lead Thin Small Outline Transistor Package [TSOT] (UJ-5) Dimensions shown in millimeters 3.20 3.00 2.80 8 3.20 3.00 2.80 1 5 5.15 4.90 4.65 4 PIN 1 0.65 BSC 0.95 0.85 0.75 1.10 MAX 0.15 0.00 0.38 0.22 COPLANARITY 0.10 0.23 0.08 8° 0° SEATING PLANE COMPLIANT TO JEDEC STANDARDS MO-187-AA Figure 49. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters Rev. E | Page 15 of 20 0.80 0.60 0.40 AD8615/AD8616/AD8618 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 8 5 1 4 6.20 (0.2441) 5.80 (0.2284) 1.27 (0.0500) BSC 1.75 (0.0688) 1.35 (0.0532) 0.25 (0.0098) 0.10 (0.0040) 0.51 (0.0201) 0.31 (0.0122) COPLANARITY 0.10 SEATING PLANE 0.50 (0.0196) 0.25 (0.0099) 45° 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 012407-A COMPLIANT TO JEDEC STANDARDS MS-012-A A 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 50. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) 8.75 (0.3445) 8.55 (0.3366) 4.00 (0.1575) 3.80 (0.1496) 8 14 1 7 6.20 (0.2441) 5.80 (0.2283) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0039) COPLANARITY 0.10 0.50 (0.0197) 0.25 (0.0098) 1.75 (0.0689) 1.35 (0.0531) SEATING PLANE 0.51 (0.0201) 0.31 (0.0122) 45° 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 060606-A COMPLIANT TO JEDEC STANDARDS MS-012-AB 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 51. 14-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-14) Dimensions shown in millimeters and (inches) 5.10 5.00 4.90 14 8 4.50 4.40 4.30 6.40 BSC 1 7 PIN 1 0.65 BSC 1.20 MAX 0.15 0.05 COPLANARITY 0.10 0.30 0.19 0.20 0.09 SEATING PLANE 8° 0° COMPLIANT TO JEDEC STANDARDS MO-153-AB-1 Figure 52. 14-Lead Thin Shrink Small Outline Package [TSSOP] (RU-14) Dimensions shown in millimeters Rev. E | Page 16 of 20 0.75 0.60 0.45 061908-A 1.05 1.00 0.80 AD8615/AD8616/AD8618 ORDERING GUIDE Model AD8615AUJZ-R2 1 AD8615AUJZ-REEL1 AD8615AUJZ-REEL71 AD8616ARM-R2 AD8616ARM-REEL AD8616ARMZ1 AD8616ARMZ-R21 AD8616ARMZ-REEL1 AD8616AR AD8616AR-REEL AD8616AR-REEL7 AD8616ARZ1 AD8616ARZ-REEL1 AD8616ARZ-REEL71 AD8618AR AD8618AR-REEL AD8618AR-REEL7 AD8618ARZ1 AD8618ARZ-REEL1 AD8618ARZ-REEL71 AD8618ARU AD8618ARU-REEL AD8618ARUZ1 AD8618ARUZ-REEL1 1 Temperature Range –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C –40°C to +125°C Package Description 5-Lead TSOT-23 5-Lead TSOT-23 5-Lead TSOT-23 8-Lead MSOP 8-Lead MSOP 8-Lead MSOP 8-Lead MSOP 8-Lead MSOP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead SOIC_N 14-Lead TSSOP 14-Lead TSSOP 14-Lead TSSOP 14-Lead TSSOP Z = RoHS Compliant Part. Rev. E | Page 17 of 20 Package Option UJ-5 UJ-5 UJ-5 RM-8 RM-8 RM-8 RM-8 RM-8 R-8 R-8 R-8 R-8 R-8 R-8 R-14 R-14 R-14 R-14 R-14 R-14 RU-14 RU-14 RU-14 RU-14 Branding BKA BKA BKA BLA BLA A0K A0K A0K AD8615/AD8616/AD8618 NOTES Rev. E | Page 18 of 20 AD8615/AD8616/AD8618 NOTES Rev. E | Page 19 of 20 AD8615/AD8616/AD8618 NOTES ©2004–2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D04648-0-9/08(E) Rev. E | Page 20 of 20