AD AD8616ARMZ-R21 Precision, 20 mhz, cmos, rail-to-rail input/output operational amplifier Datasheet

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
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