AD8616AR [ADI]
Precision 20 MHz CMOS Rail-to-Rail Input/Output Operational Amplifiers; 高精度20 MHz的CMOS轨到轨输入/输出运算放大器
| 型号： | AD8616AR |
| 厂家： | 
ADI |
| 描述： | Precision 20 MHz CMOS Rail-to-Rail Input/Output Operational Amplifiers |
| 文件： | 总16页 (文件大小：637K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Precision 20 MHz CMOS Rail-to-Rail
Input/Output Operational Amplifiers
AD8616/AD8618
FEATURES
PIN CONFIGURATIONS
Low offset voltage: 65 µV max
Single-supply operation: 2.7 V to 5.5 V
Low noise: 8 nV/√Hz
OUT A
–IN A
+IN A
V–
1
2
3
4
8
7
6
5
V+
AD8616
OUT B
–IN B
+IN B
TOP VIEW
(Not to Scale)
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 1. 8-Lead MSOP (RM-8)
OUT A
–IN A
+IN A
V–
1
2
3
4
8
7
6
5
V+
AD8616
OUT B
–IN B
+IN B
TOP VIEW
(Not to Scale)
Figure 2. 8-Lead SOIC (R-8)
APPLICATIONS
Barcode scanners
Battery-powered instrumentation
Multipole filters
OUT A
IN A
OUT D
IN D
+IN D
1
14
–
–
+IN A
V+
AD8618
V
–
+IN B
+IN C
IN C
OUT C
–IN B
–
8
7
OUT B
Sensors
ASIC input or output amplifier
Audio
Figure 3. 14-Lead TSSOP (RU-14)
Photodiode amplification
OUT A
IN A
1
2
3
4
5
6
7
14 OUT D
13 –IN D
12 +IN D
–
+IN A
V+
AD8618
11
10
9
V–
+IN B
–IN B
OUT B
+IN C
–IN C
OUT C
8
Figure 4. 14-Lead SOIC (R-14)
GENERAL DESCRIPTION
The 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
current noise. The parts use a patented trimming technique that
achieves superior precision without laser trimming. The
AD8616/AD8618 are fully specified to operate from 2.7 V to
5 V single supplies.
DigiTrimTM 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.
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 AD8616/
AD8618 offer the highest output drive capability of the
The AD8616/AD8618 are specified over the extended industrial
(–40°C to +125°C) temperature range. 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 14-lead TSSOP packages.
Rev. A
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
Fax: 781.326.8703
www.analog.com
© 2004 Analog Devices, Inc. All rights reserved.
AD8616/AD8618
TABLE OF CONTENTS
Specifications..................................................................................... 3
VS = 5 V.......................................................................................... 3
VS = 2.7 V....................................................................................... 4
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution.................................................................................. 5
Typical Performance Characteristics ............................................. 6
Applications..................................................................................... 12
Input Overvoltage Protection ................................................... 12
Output Phase Reversal............................................................... 12
Driving Capacitive Loads.......................................................... 12
Overload Recovery Time .......................................................... 13
D/A Conversion ......................................................................... 13
Low Noise Applications............................................................. 13
High Speed Photodiode Preamplifier...................................... 14
Active Filters ............................................................................... 14
Power Dissipation ...................................................................... 14
Power Calculations for Varying or Unknown Loads............. 15
Outline Dimensions....................................................................... 16
Ordering Guide .......................................................................... 16
REVISION HISTORY
4/04—Data Sheet Changed from Rev. 0 to Rev. A
Added AD8618................................................................Universal
Updated Outline Dimensions................................................... 16
1/04—Revision 0: Initial Version
Rev. A | Page 2 of 16
AD8616/AD8618
SPECIFICATIONS
VS = 5 V
@VCM = VS/2, TA = 25°C, unless otherwise noted.
Table 1.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
INPUT CHARACTERISTICS
Offset Voltage
VOS
VS = 3.5 V @ VCM = 0.5 V and 3.0 V
VCM = 0 V to 5 V
−40°C < TA < +125°C
−40°C < TA < +125°C
23
80
65
500
800
7
µV
µV
µV
Offset Voltage Drift
Input Bias Current
∆VOS/∆T
IB
1.5
0.2
µV/°C
pA
pA
pA
pA
pA
pA
V
1
−40°C < TA < +85°C
−40°C < TA < +125°C
50
500
0.5
50
250
5
Input Offset Current
IOS
0.1
−40°C < TA < +85°C
−40°C < TA < +125°C
Input Voltage Range
0
Common-Mode Rejection Ratio
Large Signal Voltage Gain
Input Capacitance
CMRR
AVO
CDIFF
CCM
VCM = 0 V to 4.5 V
RL = 2 kΩ, VO = 0.5 V to 5 V
80
105
100
1500
2.6
dB
V/mV
pF
10
pF
OUTPUT CHARACTERISTICS
Output Voltage High
VOH
IL = 1 mA
IL = 10 mA
−40°C < TA < +125°C
IL = 1 mA
IL = 10 mA
4.98
4.88
4.7
4.99
4.92
V
V
V
mV
mV
mV
mA
Ω
Output Voltage Low
VOL
7.5
70
15
100
200
−40°C < TA < +125°C
Output Current
Closed-Loop Output Impedance
POWER SUPPLY
IOUT
ZOUT
150
3
f = 1 MHz, AV = 1
Power Supply Rejection Ratio
Supply Current per Amplifier
PSRR
ISY
VS = 2.7 V to 5.5 V
VO = 0 V
−40°C < TA < +125°C
70
90
1.7
dB
mA
mA
2.0
2.5
DYNAMIC PERFORMANCE
Slew Rate
Settling Time
Gain Bandwidth Product
Phase Margin
SR
ts
GBP
ØO
RL = 2 kΩ
To 0.01%
12
<0.5
24
V/µs
µs
MHz
Degrees
73
NOISE PERFORMANCE
Peak-to-Peak Noise
Voltage Noise Density
en p-p
en
0.1 Hz to 10 Hz
f = 1 kHz
2.4
8
µV
nV/√Hz
nV/√Hz
pA/√Hz
dB
f = 10 kHz
f = 1 kHz
6
Current Noise Density
Channel Separation
in
0.05
–115
–110
Cs
f = 10 kHz
f = 100 kHz
dB
Rev. A | Page 3 of 16
AD8616/AD8618
VS = 2.7 V
@VCM = VS /2, TA = 25°C, unless otherwise noted.
Table 2.
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
INPUT CHARACTERISTICS
Offset Voltage
VOS
VS = 3.5 V @ VCM = 0.5 V and 3.0 V
VCM = 0 V to 2.7 V
−40°C < TA < +125°C
23
80
65
µV
µV
µV
500
800
7
1
50
500
0.5
50
250
2.7
Offset Voltage Drift
Input Bias Current
∆VOS/∆T
IB
−40°C < TA < +125°C
1.5
0.2
µV/°C
pA
pA
pA
pA
pA
pA
V
−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
0
Common-Mode Rejection Ratio
Large Signal Voltage Gain
Input Capacitance
CMRR
AVO
CDIFF
CCM
VCM = 0 V to 2.7 V
RL = 2 kΩ, VO = 0.5 V to 2.2 V
84
55
100
150
2.6
10
dB
V/mV
pF
pF
OUTPUT CHARACTERISTICS
Output Voltage High
VOH
VOL
IL = 1 mA
−40°C < TA < +125°C
IL = 1 mA
2.65
2.6
2.68
11
V
V
mV
mV
mA
Ω
Output Voltage Low
25
30
−40°C < TA < +125°C
Output Current
Closed-Loop Output Impedance
POWER SUPPLY
IOUT
ZOUT
50
3
f = 1 MHz, AV = 1
Power Supply Rejection Ratio
Supply Current per Amplifier
PSRR
ISY
VS = 2.7 V to 5.5 V
VO = 0 V
−40°C < TA < +125°C
70
90
1.7
dB
mA
mA
2
2.5
DYNAMIC PERFORMANCE
Slew Rate
Settling Time
Gain Bandwidth Product
Phase Margin
SR
ts
GBP
ØO
RL = 2 kΩ
To 0.01%
12
<0.3
22
V/µs
µs
MHz
Degrees
50
NOISE PERFORMANCE
Peak-to-Peak Noise
Voltage Noise Density
en p-p
en
0.1 Hz to 10 Hz
f = 1 kHz
2.1
8
µV
nV/√Hz
nV/√Hz
pA/√Hz
dB
f = 10 kHz
f = 1 kHz
6
Current Noise Density
Channel Separation
in
0.05
–115
–110
Cs
f = 10 kHz
f = 100 kHz
dB
Rev. A | Page 4 of 16
AD8616/AD8618
ABSOLUTE MAXIMUM RATINGS
Table 3. AD8616/AD8618 Stress Ratings
Parameter
Supply Voltage
THERMAL RESISTANCE
Rating
θJA is specified for the worst-case conditions, i.e., θJA is specified
for device soldered in circuit board for surface-mount packages.
6 V
GND to VS
3 V
Indefinite
–65°C to +150°C
–40°C to +125°C
300°C
Input Voltage
Table 4.
Package Type
8-Lead MSOP (RM)
8-Lead SOIC (R)
14-Lead SOIC (R)
14-Lead TSSOP (RU)
Differential Input Voltage
Ouput Short-Circuit Duration to GND
Storage Temperature
Operating Temperature Range
Lead Temperature Range (Soldering 60 sec)
Junction Temperature
θJA
θJC
45
43
36
35
Unit
°C/W
°C/W
°C/W
°C/W
210
158
120
180
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.
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. A | Page 5 of 16
AD8616/AD8618
TYPICAL PERFORMANCE CHARACTERISTICS
350
300
250
200
150
100
50
2200
V
= ±2.5V
V
= 5V
S
S
2000
1800
1600
1400
1200
1000
800
T
= 25°C
A
V
= 0V TO 5V
CM
600
400
200
0
0
–700
–500
–300
–100
100
300
V)
500
700
0
25
50
75
100
125
TEMPERATURE (°C)
OFFSET VOLTAGE (
µ
Figure 5. Input Offset Voltage Distribution
Figure 8. Input Bias Current vs. Temperature
22
20
18
16
14
12
10
8
1000
100
10
V
T
= 5V
= 25°C
V
T
= ±2.5V
= –40°C TO +125°C
= 0V
S
A
S
A
V
CM
SOURCE
SINK
6
1
4
2
0
0.1
0.001
0
2
4
6
8
10
12
0.01
0.1
1
10
100
LOAD CURRENT (mA)
TCV
(µV/°C)
OS
Figure 6. Offset Voltage Drift Distribution
Figure 9. Output Voltage to Supply Rail vs. Load Current
500
400
120
100
80
60
40
20
0
V
T
= 5V
= 25
S
A
V
= 5V
S
°C
300
10mA LOAD
200
100
0
–100
–200
–300
–400
–500
1mA LOAD
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
–40 –25 –10
5
20
35
50
65
C)
80
95 110 125
COMMON-MODE VOLTAGE (V)
TEMPERATURE (
°
Figure 10. Output Voltage Swing vs. Temperature
Figure 7. Input Offset Voltage vs. Common-Mode Voltage
(200 Units, Five Wafer Lots Including Process Skews)
Rev. A | Page 6 of 16
AD8616/AD8618
120
100
80
60
40
20
0
100
80
225
180
135
90
V
T
= ±2.5V
= 25°C
= 74°
S
A
V
= ±2.5V
S
φ
M
60
40
45
20
0
0
–45
–90
–20
–40
1k
10k
100k
1M
10M
100M
1k
10k
100k
1M
10M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 11. Open-Loop Gain and Phase vs. Frequency
Figure 14. Common-Mode Rejection Ratio vs. Frequency
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
120
100
80
60
40
20
0
V
= ±2.5V
V
V
T
R
A
= 5.0V
= 4.9V p-p
= 25°C
= 2kΩ
= 1
S
S
IN
A
L
V
1k
10k
100k
1M
10M
1k
10k
100k
1M
10M
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 12. Closed-Loop Output Voltage Swing
Figure 15. PSRR vs. Frequency
100
90
80
70
60
50
40
30
20
10
0
50
45
40
35
30
25
20
15
10
5
V
= ±2.5V
S
V
R
= 5V
= ∞
= 25°C
= 1
S
L
T
A
A
V
A
= 100
A = 1
V
V
–OS
+OS
A
= 10
V
0
1k
10k
100k
1M
10M
100M
10
100
1000
FREQUENCY (Hz)
CAPACITANCE (pF)
Figure 13. Output Impedance vs. Frequency
Figure 16. Small-Signal Overshoot vs. Load Capacitance
Rev. A | Page 7 of 16
AD8616/AD8618
2.4
2.2
2.0
56
49
42
35
28
21
14
7
V
= 5V
S
MKR @ 6.70
V
= 2.7V
S
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
V
= 5V
S
0
–40 –25 –10
5
20
35
50
65
C)
80
95 110 125
0
1
2
3
4
5
6
7
8
9
10
FREQUENCY (kHz)
TEMPERATURE (
°
Figure 17. Supply Current vs. Temperature
Figure 20. Voltage Noise Density vs. Frequency
2000
1800
1600
1400
1200
1000
800
V
= 5V
= 10kΩ
= 200pF
= 1
S
R
C
A
L
L
V
600
400
200
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
TIME (1µs/DIV)
SUPPLY VOLTAGE (V)
Figure 21. Small-Signal Transient Response
Figure 18. Supply Current vs. Supply Voltage
V
= 5V
72
63
54
45
36
27
18
9
S
R
C
A
= 10kΩ
= 200pF
= 1
V
= 5V
L
L
V
S
MKR @ 8.72
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
TIME (1µs/DIV)
FREQUENCY (kHz)
Figure 22. Large-Signal Transient Response
Figure 19. Voltage Noise Density vs. Frequency
Rev. A | Page 8 of 16
AD8616/AD8618
0.1
0.01
1400
1200
1000
800
600
400
200
0
V
V
A
= ±2.5V
= 0.5V rms
= 1
S
V
T
= 2.7V
= 25°C
= 0V TO 2.7V
S
IN
A
V
V
CM
BW = 22kHz
R
= 100kΩ
L
0.001
0.0001
–700
–500
–300
–100
100
300
V)
500
700
20
100
1k
20k
FREQUENCY (Hz)
OFFSET VOLTAGE (
µ
Figure 23. THD + N
Figure 26. Input Offset Voltage Distribution
500
400
V
V
A
= ±2.5V
= 2V p-p
= 10
S
V
T
= 2.7V
= 25°C
S
A
IN
V
300
200
100
0
–100
–200
–300
–400
–500
0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
TIME (200ns/DIV)
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
400
V
= 2.7V
S
V
T
= 3.5V
= 25°C
S
A
300
200
100
0
–100
–200
–300
–400
–500
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
TIME (1s/DIV)
COMMON-MODE VOLTAGE (V)
Figure 25. 0.1 Hz to 10 Hz Input Voltage Noise
Figure 28. Input Offset Voltage vs. Common-Mode Voltage
(200 Units, Five Wafer Lots Including Process Skews)
Rev. A | Page 9 of 16
AD8616/AD8618
1000
2.7
2.4
2.1
1.8
1.5
1.2
0.9
0.6
0.3
0
V
T
= 2.7V
= 25°C
S
V
V
T
R
A
= 2.7V
S
A
= 2.6V p-p
IN
A
= 25
= 2k
= 1
°C
Ω
100
10
1
L
V
SOURCE
SINK
0.1
0.001
0.01
0.1
LOAD CURRENT (mA)
1
10
1k
10k
100k
1M
10M
FREQUENCY (Hz)
Figure 29. Output Voltage to Supply Rail vs. Load Current
Figure 32. Closed-Loop Output Voltage Swing vs. Frequency
18
16
14
12
10
8
50
45
40
35
30
25
20
15
10
5
V
= 2.7V
V
= ±1.35V
S
S
R
T
= ∞
L
= 25°C
V
@ 1mA LOAD
A
OH
A
= 1
V
V
@ 1mA LOAD
OL
–OS
+OS
6
4
2
0
0
10
100
CAPACITANCE (pF)
1000
–40 –25 –10
5
20
35
50
65
80
95 110 125
TEMPERATURE (°C)
Figure 30. Output Voltage Swing vs. Temperature
Figure 33. Small-Signal Overshoot vs. Load Capacitance
100
80
225
180
135
90
64
V
T
= ±1.35V
= 25°C
= 51°
S
V
= 2.7V
S
A
MKR @ 7.47
56
48
40
32
24
16
8
φ
M
60
40
20
45
0
0
–20
–40
–60
–80
–100
–45
–90
–135
–180
–225
0
1k
10k
100k
1M
10M
100M
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1.0
FREQUENCY (kHz)
FREQUENCY (Hz)
Figure 31. Open-Loop Gain and Phase vs. Frequency
Figure 34. Voltage Noise Density vs. Frequency
Rev. A | Page 10 of 16
AD8616/AD8618
48
42
36
30
24
18
12
6
V
= 2.7V
= 10kΩ
= 200pF
= 1
S
V
= 2.7V
S
R
C
A
L
L
V
MKR @ 5.91
0
0
1
2
3
4
5
6
7
8
9
10
TIME (1µs/DIV)
FREQUENCY (kHz)
Figure 37. Large-Signal Transient Response
Figure 35. Voltage Noise Density vs. Frequency
V
= 2.7V
= 10kΩ
= 200pF
= 1
S
R
C
A
L
L
V
TIME (1µs/DIV)
Figure 36. Small-Signal Transient Response
Rev. A | Page 11 of 16
AD8616/AD8618
APPLICATIONS
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.
INPUT OVERVOLTAGE PROTECTION
The 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.
Figure 40 shows the implementation of the snubber, which
reduces overshoot by more than 30% and eliminates ringing,
which can cause instability. Using the snubber does not recover
the loss of bandwidth incurred from a heavy capacitive load.
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.
V
A
C
= ±2.5V
= 1
= 500pF
S
V
L
For example, a 10 kΩ resistor has less than 13 nV/√ of
Hz
thermal noise and less than 10 nV of error voltage at room
temperature.
OUTPUT PHASE REVERSAL
The 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 lock-ups to systems with feedback loops.
Figure 39. Driving Heavy Capacitive Loads without Compensation
V
V
A
R
= ±2.5V
S
= 6V p-p
= 1
IN
V
V
L
CC
= 10kΩ
+
V–
V+
–
200Ω
500pF
+
V
OUT
500pF
–
V
V
EE
IN
200mV
Figure 40. Snubber Network
V
= ±2.5V
= 1
S
A
R
C
C
V
S
S
L
= 200
Ω
TIME (2ms/DIV)
= 500pF
= 500pF
Figure 38. No Phase Reversal
DRIVING CAPACITIVE LOADS
Although the 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. This reduces the overshoot and minimizes
ringing, which in turn improves the frequency response of the
TIME (10µs/DIV)
Figure 41. Driving Heavy Capacitive Loads Using the Snubber Network
Rev. A | Page 12 of 16
AD8616/AD8618
5V
2.5V
OVERLOAD RECOVERY TIME
10
µF
+
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 42 and Figure 43 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 for excellent
signal rectification without distortion to the output signal.
0.1µF
0.1µF
SERIAL
INTERFACE
V
REFF
REFS
DD
1/2
AD8616
CS
UNIPOLAR
OUTPUT
DIN
AD5542
V
OUT
SCLK
LDAC*
DGND
AGND
Figure 44. Buffering DAC Output
LOW NOISE APPLICATIONS
V
R
A
= ±2.5V
= 10kΩ
= 100
S
L
Although the AD8618 typically has less than 8 nV/√ of
Hz
V
+2.5V
V
= 50mV
IN
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 45. The total noise at the output is divided by
the square root of the number of amplifiers. In this case, the
0V
0V
total noise is approximately 4 nV/√ at room temperature.
Hz
The 100 Ω resistor limits the current and provides an effective
output resistance of 50 Ω.
3
V
–50mV
IN
R3
V+
V–
1
1
1
1
R1
2
100Ω
10Ω
TIME (1µs/DIV)
R2
Figure 42. Positive Overload Recovery
1kΩ
V
R
A
= ±2.5V
= 10kΩ
= 100
S
3
L
R6
V+
V–
V
V
= 50mV
IN
R4
2
100Ω
10Ω
–2.5V
0V
0V
R5
V
OUT
1kΩ
3
2
R9
V+
V–
R7
100Ω
10Ω
R8
+50mV
1kΩ
3
2
TIME (1µs/DIV)
R12
V+
V–
R10
Figure 43. Negative Overload Recovery
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.
1kΩ
Figure 45. Noise Reduction
Figure 44 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. A | Page 13 of 16
AD8616/AD8618
10
0
HIGH SPEED PHOTODIODE PREAMPLIFIER
The 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.
–10
–20
–30
–40
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.
The total input capacitance, C1, is the sum of the diode
capacitance and that of the op amp. This creates a feedback pole
and causes degradation of the phase margin, making the op
amp unstable. It is therefore necessary to use a capacitor in the
feedback to compensate for this pole.
0.1
1
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
Figure 48. Second-Order Butterworth Low-Pass Filter Frequency Response
To get the maximum signal bandwidth, select
POWER DISSIPATION
C1
C2 =
Although the AD8616/AD8618 are capable of providing load
currents to 150 mA, the usable output load current drive
capability is limited to the maximum power dissipation allowed
by the device package used. In any application, the absolute
maximum junction temperature for the AD8616/AD8618 is
150°C; this should never be exceeded because the device could
suffer premature failure. Accurately measuring power dissipa-
tion of an integrated circuit is not always a straightforward
exercise; Figure 49 has been provided as a design aid for setting
a safe output current drive level or selecting a heat sink for the
package options available on the AD8616.
2πR2 fU
where fU is the unity gain bandwidth of the amplifier.
C2
R2
+2.5V
–
V–
I
R
C
C
IN
D
SH
D
V+
+
–2.5V
–V
BIAS
1.5
Figure 46. High Speed Photodiode Preamplifier
ACTIVE FILTERS
1.0
The low input bias current and high unity gain bandwidth of
the AD8616 make it an excellent choice for precision filter
design.
SOIC
MSOP
Figure 47 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 48.
0.5
0
2nF
0
20
40
60
80
100
120
140
TEMPERATURE (°C)
V
CC
Figure 49. Maximum Power Dissipation vs. Ambient Temperature
V–
V+
1.1kΩ
1.1kΩ
V
1nF
IN
V
EE
Figure 47. Second-Order Low-Pass Filter
Rev. A | Page 14 of 16
AD8616/AD8618
Calculating Power by Measuring Ambient and Case
Temperature
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 AD8616/AD8618 for any application:
Given the two equations for calculating junction temperature:
TJ = TA + P θJA
where:
TJ = PDISS × θJA + TA
TJ = junction temperature;
TA = ambient temperature.
where:
θJA = the junction-to-ambient thermal resistance.
TJ = junction temperature;
P
DISS = power dissipation;
TJ = TC + P θJC
θJA = package thermal resistance, junction-to-case; and
TA = ambient temperature of the circuit.
where TC is case temperature and θJA and θJC are given in the
data sheet.
To calculate the power dissipated by the AD8616/AD8618, use
the following equation:
The two equations can be solved for P (power):
TA + P θJA = TC + P θJC
P
DISS = ILOAD × (VS – VOUT)
where:
P = (TA – TC)/(θJC – θJA)
I
LOAD = output load current;
Once power has been determined, it is necessary to go back and
calculate the junction temperature to assure that it has not been
exceeded.
VS = supply voltage; and
V
OUT = output voltage.
The quantity within the parentheses is the maximum voltage
developed across either output transistor.
The temperature measurements should be directly on the
package and on a spot on the board that is near the package but
not touching it. Measuring the package could be difficult. A very
small bimetallic junction glued to the package could be used; an
infrared sensing device could 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.
Calculating Power by Measuring Supply Current
Power can be calculated directly if the supply voltage and
current are known. However, supply current may have a dc
component with a pulse into a capacitive load. This could make
rms current very difficult to calculate. This can be overcome by
lifting the supply pin and inserting an rms current meter into
the circuit. For this to work, the user must be sure that all of the
current is being 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.
There are two methods to calculate power dissipated by an
integrated circuit. The first can be done by measuring the
package temperature and the board temperature. The other is to
directly measure the circuit’s supply current.
Rev. A | Page 15 of 16
AD8616/AD8618
OUTLINE DIMENSIONS
3.00
BSC
8.75 (0.3445)
8.55 (0.3366)
14
1
8
7
8
5
4
4.00 (0.1575)
3.80 (0.1496)
6.20 (0.2441)
5.80 (0.2283)
4.90
BSC
3.00
BSC
1.27 (0.0500)
BSC
0.50 (0.0197)
0.25 (0.0098)
1.75 (0.0689)
1.35 (0.0531)
× 45°
PIN 1
0.25 (0.0098)
0.10 (0.0039)
0.65 BSC
8°
0°
0.51 (0.0201)
0.31 (0.0122)
1.10 MAX
SEATING
PLANE
0.15
0.00
1.27 (0.0500)
0.40 (0.0157)
COPLANARITY
0.10
0.25 (0.0098)
0.17 (0.0067)
0.80
0.60
0.40
8°
0°
0.38
0.22
0.23
0.08
COMPLIANT TO JEDEC STANDARDS MS-012AB
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COPLANARITY
0.10
SEATING
PLANE
COMPLIANT TO JEDEC STANDARDS MO-187AA
Figure 52. 14-Lead Standard Small Outline Package [SOIC]
(R-14)
Figure 50. 8-Lead Micro Small Outline Package [MSOP]
(RM-8)
Dimensions shown in millimeters and (inches)
Dimensions shown in millimeters
5.10
5.00
4.90
5.00 (0.1968)
4.80 (0.1890)
8
1
5
4
14
8
7
6.20 (0.2440)
5.80 (0.2284)
4.00 (0.1574)
3.80 (0.1497)
4.50
4.40
4.30
6.40
BSC
1.27 (0.0500)
BSC
0.50 (0.0196)
0.25 (0.0099)
1
× 45°
1.75 (0.0688)
1.35 (0.0532)
0.25 (0.0098)
PIN 1
0.10 (0.0040)
0.65
BSC
1.05
1.00
0.80
8°
0.51 (0.0201)
0.31 (0.0122)
0° 1.27 (0.0500)
COPLANARITY
0.10
0.20
0.09
0.25 (0.0098)
0.17 (0.0067)
1.20
MAX
SEATING
PLANE
0.40 (0.0157)
0.75
0.60
0.45
8°
0°
0.15
0.05
0.30
0.19
COMPLIANT TO JEDEC STANDARDS MS-012AA
SEATING
PLANE
COPLANARITY
0.10
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MO-153AB-1
Figure 53. 14-Lead Thin Shrink Small Outline Package [TSSOP]
(RU-14)
Figure 51. 8-Lead Standard Small Outline Package [SOIC]
(R-8)
Dimensions shown in millimeters
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model
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
Package Description
8-Lead MSOP
8-Lead MSOP
8-Lead SOIC
8-Lead SOIC
8-Lead SOIC
14-Lead SOIC
14-Lead SOIC
14-Lead SOIC
14-Lead TSSOP
14-Lead TSSOP
Package Outline
Branding Code
AD8616ARM-R2
AD8616ARM-REEL
AD8616AR
AD8616AR-REEL
AD8616AR-REEL7
AD8618AR
AD8618AR-REEL
AD8618AR-REEL7
AD8618ARU
RM-8
RM-8
R-8
R-8
R-8
R-14
R-14
R-14
RU-14
RU-14
BLA
BLA
AR8618ARU-REEL
©
2004 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D04648–0–4/04(A)
Rev. A | Page 16 of 16
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