Precision, 20 MHz, CMOS, Rail-to-Rail Input/Output Operational Amplifiers AD8615/AD8616/AD8618 FEATURES 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. Low offset voltage: 65 μV max Single-supply operation: 2.7 V to 5.5 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 The combination of 20 MHz bandwidth, low offset, low noise, and very low input bias current make 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 DigiTrimTM family, which is excellent for audio line drivers and other low impedance applications. APPLICATIONS Barcode scanners Battery-powered instrumentation Multipole filters Sensors ASIC input or output amplifier Audio Photodiode amplification 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. GENERAL DESCRIPTION The AD8615/AD8616/AD8618 are dual/quad, rail-to-rail, input and output, single-supply amplifiers featuring very low offset voltage, wide signal bandwidth, and low input voltage and The AD8615/AD8616/AD8618 are specified over the extended industrial (–40°C to +125°C) temperature range. The AD8615 is available in 5-lead TSOT-23 packages. 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. PIN CONFIGURATIONS 5 OUT A –IN A +IN A V+ +IN B –IN B OUT B V+ AD8615 +IN 3 TOP VIEW (Not to Scale) 4 –IN 04648-B-050 V– 2 1 OUT D –IN D +IN D V– +IN C –IN C OUT C 14 AD8618 8 7 04648-0-048 OUT 1 Figure 4. 14-Lead TSSOP (RU-14) Figure 1. 5-Lead TSOT-23 (UJ-5) AD8616 +IN A 3 TOP VIEW V– 4 (Not to Scale) OUT B –IN A 2 6 –IN B +IN A 3 5 +IN B 7 V+ 4 +IN B 5 –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 04648-0-002 Figure 2. 8-Lead MSOP (RM-8) OUT A 1 14 OUT D OUT A 1 V+ 13 –IN D 12 +IN D AD8618 11 V– 10 +IN C –IN B 6 9 –IN C OUT B 7 8 OUT C 04648-0-049 –IN A 2 8 04648-0-001 OUT A 1 Figure 5. 14-Lead SOIC (R-14) Figure 3. 8-Lead SOIC (R-8) Rev. C 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 © 2005 Analog Devices, Inc. All rights reserved. AD8615/AD8616/AD8618 TABLE OF CONTENTS Specifications..................................................................................... 3 Overload Recovery Time .......................................................... 12 Absolute Maximum Ratings............................................................ 5 D/A Conversion ......................................................................... 12 Thermal Resistance ...................................................................... 5 Low Noise Applications............................................................. 12 ESD Caution.................................................................................. 5 High Speed Photodiode Preamplifier...................................... 13 Typical Performance Characteristics ............................................. 6 Active Filters ............................................................................... 13 Applications..................................................................................... 11 Power Dissipation....................................................................... 13 Input Overvoltage Protection ................................................... 11 Power Calculations for Varying or Unknown Loads............. 14 Output Phase Reversal............................................................... 11 Outline Dimensions ....................................................................... 15 Driving Capacitive Loads .......................................................... 11 Ordering Guide .......................................................................... 17 REVISION HISTORY 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 Subsequent Figures .............. 8 Changes to Figure 20.................................................................... 9 Changes to Figure 29.................................................................. 10 Changes to Figure 31.................................................................. 11 Deleted Figure 34; Renumbered Subsequent Figures ............ 11 Deleted Figure 35; Renumbered Subsequent Figures ............ 35 4/04—Rev. 0 to Rev. A Added AD8618 ...............................................................Universal Updated Outline Dimensions ................................................... 16 1/04—Revision 0: Initial Version Rev. C | 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/ AD8615 Offset Voltage Drift AD8616/AD8618/ 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. C | Page 3 of 20 70 90 1.7 V V V mV mV mV mA Ω 2.0 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/ AD8615 Offset Voltage Drift AD8616/AD8618/ 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. C | 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 Table 3. Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration to GND Storage Temperature Operating Temperature Range Lead Temperature Range (Soldering 60 sec) Junction Temperature THERMAL RESISTANCE 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 and 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 device soldered in 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) θJA 207 210 158 120 180 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. C | Page 5 of 20 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 50 200 –500 –300 –100 100 300 500 700 0 OFFSET VOLTAGE (μV) 0 25 75 100 125 TEMPERATURE (°C) Figure 6. Input Offset Voltage Distribution Figure 9. Input Bias Current vs. Temperature 22 1000 VS = ±2.5V TA = –40°C TO +125°C VCM = 0V 20 18 VS = 5V TA = 25°C 16 100 14 VSY–VOUT (mV) 12 10 8 10 SINK SOURCE 6 04648-B-007 1 4 2 0 2 4 6 8 10 0.1 0.001 04648-0-004 0 12 TCVOS (μV/°C) 0.1 1 ILOAD (mA) 100 10 Figure 10. Output Voltage to Supply Rail vs. Load Current Figure 7. Offset Voltage Drift Distribution 500 120 VS = 5V TA = 25°C 400 VS = 5V 100 300 OUTPUT VOLTAGE (mV) 10mA LOAD 200 100 0 –100 –200 80 60 40 –300 20 –400 1mA LOAD –500 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 COMMON-MODE VOLTAGE (V) 04648-0-005 INPUT OFFSET VOLTAGE (μV) 0.01 Figure 8. Input Offset Voltage vs. Common-Mode Voltage (200 Units, Five Wafer Lots Including Process Skews) 0 –40 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) Figure 11. Output Saturation Voltage vs. Temperature Rev. C | Page 6 of 20 04648-0-008 NUMBER OF AMPLIFIERS 50 04648-0-006 –700 04648-0-003 0 AD8615/AD8616/AD8618 100 VS = ±2.5V 100 135 45 0 0 –20 –45 –40 –90 –60 –135 –80 –180 –100 1M –225 60M 10M FREQUENCY (Hz) 80 60 40 20 0 1k 100k 1M 10M FREQUENCY (Hz) Figure 12. Open-Loop Gain and Phase vs. Frequency Figure 15. Common-Mode Rejection Ratio 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) 10k 04648-0-012 90 20 CMRR (dB) 40 PHASE (Degrees) 60 180 04648-B-009 80 GAIN (dB) 120 225 VS = ±2.5V TA = 25°C Øm = 63° 2.5 2.0 60 40 1.5 1.0 20 0.5 10k 100k 1M 10M FREQUENCY (Hz) 0 1k 10k Figure 13. Closed-Loop Output Voltage Swing 60 50 40 30 AV = 100 AV = 1 AV = 10 10 10k 100k 40 35 30 25 20 15 –OS 10 +OS 5 1M 10M FREQUENCY (Hz) 100M 0 10 100 1000 CAPACITANCE (pF) Figure 17. Small-Signal Overshoot vs. Load Capacitance Figure 14. Output Impedance vs. Frequency Rev. C | Page 7 of 20 04648-0-014 SMALL-SIGNAL OVERSHOOT (%) 70 20 VS = 5V RL = ∞ TA = 25°C AV = 1 45 04648-0-011 OUTPUT IMPEDANCE (Ω) 10M 50 VS = ±2.5V 80 0 1k 1M Figure 16. PSRR vs. Frequency 100 90 100k FREQUENCY (Hz) 04648-0-013 1k 04648-0-010 0 AD8615/AD8616/AD8618 VS = 5V RL = 10kΩ CL = 200pF AV = 1 2.2 2.0 VOLTAGE (50mV/DIV) VS = 2.7V 1.8 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) 04648-0-019 0.2 04648-0-015 SUPPLY CURRENT PER AMPLIFIER (mA) 2.4 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 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 04648-0-016 0 5.0 SUPPLY VOLTAGE (V) 04648-0-020 200 TIME (1μs/DIV) Figure 22. Large-Signal Transient Response Figure 19. Supply Current vs. Supply Voltage 0.1 1k VS = ±2.5V VIN = 0.5V rms AV = 1 BW = 22kHz RL = 100kΩ VS = ±2.5V VS = ±1.35V 0.01 THD+N (%) 100 0.001 1 10 100 1k FREQUENCY (Hz) 10k 0.0001 20 100k 100 1k FREQUENCY (Hz) Figure 20. Voltage Noise Density vs. Frequency Figure 23. THD + N Rev. C | Page 8 of 20 20k 04648-0-021 10 04648-B-017 VOLTAGE NOISE DENSITY (nV/ Hz 0.5) SUPPLY CURRENT PER AMPLIFIER (μA) 2000 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 04648-0-025 04648-0-022 –500 2.7 COMMON-MODE VOLTAGE (V) Figure 24. Settling Time 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 TIME (1s/DIV) –500 0 1.5 2.0 2.5 3.0 3.5 Figure 28. Input Offset Voltage vs. Common-Mode Voltage (200 Units, Five Wafer Lots Including Process Skews) 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 04648-B-027 1 200 0 –700 –500 –300 –100 100 300 500 OFFSET VOLTAGE (μV) 700 04648-0-024 NUMBER OF AMPLIFIERS 1.0 COMMON-MODE VOLTAGE (V) Figure 25. 0.1 Hz to 10 Hz Input Voltage Noise 1200 0.5 04648-0-026 04648-0-023 –400 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. C | Page 9 of 20 10 AD8615/AD8616/AD8618 18 50 VS = 2.7V SMALL SIGNAL OVERSHOOT (%) VOH @ 1mA LOAD 12 10 VOL @ 1mA LOAD 8 6 4 2 40 35 30 25 –OS +OS 20 15 10 –25 –10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) 0 04648-0-028 0 –40 10 Figure 30. Output Saturation Voltage vs. Temperature 100 40 90 20 45 0 0 –20 –45 –40 –90 –60 –135 –80 –180 –100 1M –225 60M 10M FREQUENCY (Hz) VOLTAGE (50mV/DIV) 135 PHASE (Degrees) 60 VS = 2.7V RL = 10kΩ CL = 200pF AV = 1 180 04648-B-029 80 1000 Figure 33. Small-Signal Overshoot vs. Load Capacitance 225 VS = ±1.35V TA = 25°C Øm = 42° 100 CAPACITANCE (pF) 04648-0-0331 5 TIME (1μs/DIV) Figure 31. Open-Loop Gain and Phase vs. Frequency 04648-0-034 OUTPUT VOLTAGE (mV) 14 GAIN (dB) VS = ±1.35V RL = ∞ TA = 25°C AV = 1 45 16 Figure 34. Small-Signal Transient Response 2.7 1.8 VOLTAGE (500mV/DIV) 2.1 1.5 1.2 0.9 0.6 0 1k 10k 100k 1M 10M FREQUENCY (Hz) Figure 32. Closed-Loop Output Voltage Swing vs. Frequency TIME (1μs/DIV) Figure 35. Large-Signal Transient Response Rev. C | Page 10 of 20 04648-0-035 0.3 04648-0-030 OUTPUT SWING (V p-p) VS = 2.7V RL = 10kΩ CL = 200pF AV = 1 VS = 2.7V VIN = 2.6V p-p TA = 25°C RL = 2kΩ AV = 1 2.4 AD8615/AD8616/AD8618 APPLICATIONS 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. 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 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 04648-0-037 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) Phase reversal can cause permanent damage to the amplifier and can create lock-ups in systems with feedback loops. Figure 37. Driving Heavy Capacitive Loads Without Compensation VCC – V– V+ 200Ω 500pF + – VOUT 200mV VEE 500pF VIN 04648-0-038 + 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) 04648-0-039 TIME (2ms/DIV) VOLTAGE (100mV/DIV) Figure 38. Snubber Network 04648-0-036 VOLTAGE (2V/DIV) VS = ±2.5V VIN = 6V p-p AV = 1 RL = 10kΩ Figure 39. Driving Heavy Capacitive Loads Using the Snubber Network Rev. C | Page 11 of 20 AD8615/AD8616/AD8618 5V OVERLOAD RECOVERY TIME REFF REFS 1/2 AD8616 DIN SCLK AD5542 OUT 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 04648-0-040 0V –50mV VDD CS LOW NOISE APPLICATIONS VS = ±2.5V RL = 10kΩ AV = 100 VIN = 50mV +2.5V 0.1μF 0.1μF SERIAL INTERFACE 10μF + 04648-0-042 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 3 VIN V+ R1 2 1 V– R3 100Ω 10Ω TIME (1μs/DIV) R2 Figure 40. Positive Overload Recovery 1kΩ VS = ±2.5V RL = 10kΩ AV = 100 VIN = 50mV 3 V+ R4 2 1 V– R6 100Ω 10Ω –2.5V R5 0V VOUT 1kΩ 0V 3 V+ R7 2 1 R9 V– 100Ω 10Ω R8 +50mV V+ R10 Figure 41. Negative Overload Recovery 2 1 V– R12 100Ω 10Ω D/A CONVERSION R11 The AD8616 can be used at the output of high resolution DACs. Their low offset voltage, fast slew rate, and fast settling time make the parts 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. C | Page 12 of 20 1kΩ Figure 43. Noise Reduction 04648-0-043 TIME (1μs/DIV) 04648-0-041 1kΩ 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. –30 –40 0.1 1 10 100 1k 10k 100k 1M FREQUENCY (Hz) Figure 46. Second-Order Butterworth, Low-Pass Filter Frequency Response Although the AD8615/AD8616/AD8618 are capable of providing load currents up to 150 mA, the usable output, load current, and drive capability is limited to the maximum power dissipation allowed by the device package. C1 C2 = 2 πR 2 f U where fU is the unity-gain bandwidth of the amplifier. 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. C2 R2 +2.5V + V– V+ –2.5V –VBIAS 1.5 Figure 44. High Speed Photodiode Preamplifier 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, lowpass 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. 1.0 SOIC MSOP 0.5 0 0 20 40 60 80 100 TEMPERATURE (°C) 120 140 2nF Figure 47. Maximum Power Dissipation vs. Ambient Temperature VCC V– VIN 1.1kΩ V+ 1nF VEE 04648-0-045 1.1kΩ Figure 45. Second-Order, Low-Pass Filter Rev. C | Page 13 of 20 04648-0-047 CIN POWER DISSIPATION (W) CD 04648-0-044 – RSH –20 POWER DISSIPATION To get the maximum signal bandwidth, select ID –10 04648-0-046 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 preamps. AD8615/AD8616/AD8618 These thermal resistance curves were determined using the AD8616 thermal resistance data for each package and a maximum junction temperature of 150°C. 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 and Case Temperature The two equations for calculating junction temperature are TJ = TA + P θJA where: TJ = PDISS × θJA + TA TJ = junction temperature TA = ambient temperature θJA = the junction-to-ambient thermal resistance where: TJ = junction temperature PDISS = power dissipation θJA = package thermal resistance, junction-to-case TA = ambient temperature of the circuit TJ = TC + P θJC where TC is case temperature and θJA and θJC are given in the data sheet. To calculate the power dissipated by the AD8615/ AD8616/AD8618, use The two equations for calculating P (power) are PDISS = ILOAD × (VS – VOUT) TA + P θJA = TC + P θJC where: P = (TA – TC)/(θJC – θJA) ILOAD = output load current VS = supply voltage VOUT = output voltage Once power has been determined, it is necessary to recalculate the junction temperature to ensure that it has not been exceeded. The quantity within the parentheses is the maximum voltage developed across either output transistor. 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. 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 might 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 circuits supply current. Calculating Power by Measuring Supply Current Power can be calculated directly if the supply voltage and current are known. However, the supply current can have a dc component with a pulse directed into a capacitive load, which could 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 singlesupply system; however, if the system uses dual supplies, both supplies may need to be monitored. Rev. C | Page 14 of 20 AD8615/AD8616/AD8618 OUTLINE DIMENSIONS 3.00 BSC 8 3.00 BSC 8.75 (0.3445) 8.55 (0.3366) 5 4.00 (0.1575) 3.80 (0.1496) 4.90 BSC 1 14 8 1 7 6.20 (0.2441) 5.80 (0.2283) 4 1.27 (0.0500) BSC PIN 1 0.25 (0.0098) 0.10 (0.0039) 0.65 BSC 1.10 MAX 0.15 0.00 0.38 0.22 COPLANARITY 0.10 0.80 0.60 0.40 8° 0° 0.23 0.08 0.51 (0.0201) 0.31 (0.0122) COPLANARITY 0.10 0.50 (0.0197) × 45° 0.25 (0.0098) 1.75 (0.0689) 1.35 (0.0531) SEATING PLANE 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MO-187-AA 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 48. 8-Lead Mini Small Outline Package [MSOP] (RM-8) Dimensions shown in millimeters Figure 50. 14-Lead Standard Small Outline Package [SOIC] Narrow Body (R-14) Dimensions shown in millimeters and (inches) SEATING PLANE 5.10 5.00 4.90 5.00 (0.1968) 4.80 (0.1890) 8 4.00 (0.1574) 3.80 (0.1497) 1 5 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 14 6.20 (0.2440) 4 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) COPLANARITY 0.31 (0.0122) SEATING 0.10 PLANE 8 4.50 4.40 4.30 0.50 (0.0196) × 45° 0.25 (0.0099) 6.40 BSC 1 7 PIN 1 1.05 1.00 0.80 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012-AA 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 0.65 BSC 1.20 MAX 0.15 0.05 0.30 0.19 0.20 0.09 SEATING COPLANARITY PLANE 0.10 8° 0° COMPLIANT TO JEDEC STANDARDS MO-153-AB-1 Figure 51. 14-Lead Thin Shrink Small Outline Package [TSSOP] (RU-14) Dimensions shown in millimeters Figure 49. 8-Lead Standard Small Outline Package [SOIC] Narrow Body (R-8) Dimensions shown in millimeters and (inches) Rev. C | Page 15 of 20 0.75 0.60 0.45 AD8615/AD8616/AD8618 2.90 BSC 5 4 2.80 BSC 1.60 BSC 1 2 3 PIN 1 0.95 BSC 1.90 BSC *0.90 0.87 0.84 *1.00 MAX 0.10 MAX 0.50 0.30 0.20 0.08 SEATING PLANE 8° 4° 0° *COMPLIANT TO JEDEC STANDARDS MO-193-AB WITH THE EXCEPTION OF PACKAGE HEIGHT AND THICKNESS. Figure 52. 5-Lead Thin Small Outline Transistor Package [TSOT] (UJ-5) Dimensions shown in millimeters Rev. C | Page 16 of 20 0.60 0.45 0.30 AD8615/AD8616/AD8618 ORDERING GUIDE Model AD8615AUJZ-R2 1 AD8615AUJZ-REEL1 AD8615AUJZ-REEL71 AD8616ARM-R2 AD8616ARM-REEL 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 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 SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 8-Lead SOIC 14-Lead SOIC 14-Lead SOIC 14-Lead SOIC 14-Lead SOIC 14-Lead SOIC 14-Lead SOIC 14-Lead TSSOP 14-Lead TSSOP 14-Lead TSSOP 14-Lead TSSOP Z = Pb-free part. Rev. C | Page 17 of 20 Package Option UJ-5 UJ-5 UJ-5 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 AD8615/AD8616/AD8618 NOTES Rev. C | Page 18 of 20 AD8615/AD8616/AD8618 NOTES Rev. C | Page 19 of 20 AD8615/AD8616/AD8618 NOTES © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D04648–0–6/05(C) Rev. C | Page 20 of 20