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24 MHz Rail-to-Rail Amplifiers
with Shutdown Option
AD8646/AD8647/AD8648
FEATURES
Offset voltage: 2.5 mV maximum
Single-supply operation: 2.7 V to 5.5 V
Low noise: 8 nV/√Hz
Wide bandwidth: 24 MHz
Slew rate: 11 V/μs
Short-circuit output current: 120 mA
Qualified for automotive applications
No phase reversal
Low input bias current: 1 pA
Low supply current per amplifier: 2 mA maximum
Unity gain stable
PIN CONFIGURATIONS
OUTA
1
–INA
2
8
V+
OUTB
06527-001
06527-003
06527-002
AD8646
7
TOP VIEW
+INA
3
6
–INB
(Not to Scale)
V–
4
5
+INB
Figure 1. 8-Lead SOIC and MSOP
OUTA
1
–INA
2
+INA
3
V–
4
SDA
5
10
V+
AD8647
TOP VIEW
(Not to Scale)
9
8
7
6
OUTB
–INB
+INB
SDB
Figure 2. 10-Lead MSOP
OUTA
1
–INA
2
+INA
3
V+
4
+INB
5
–INB
6
OUTB
7
14
13
APPLICATIONS
Battery-powered instruments
Multipole filters
ADC front ends
Sensors
Barcode scanners
ASIC input or output amplifiers
Audio amplifiers
Photodiode amplifiers
Datapath/mux/switch control
OUTD
–IND
+IND
V–
+INC
–INC
OUTC
AD8648
TOP VIEW
(Not to Scale)
12
11
10
9
8
Figure 3. 14-Lead SOIC and TSSOP
GENERAL DESCRIPTION
The AD8646 and the AD8647 are the dual, and the AD8648 is
the quad, rail-to-rail, input and output, single-supply amplifiers
featuring low offset voltage, wide signal bandwidth, low input
voltage, and low current noise. The AD8647 also has a low
power shutdown function.
The combination of 24 MHz bandwidth, low offset, low noise,
and very 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. TheAD8646/
AD8647/AD8648 offer high output drive capability, which is
excellent for audio line drivers and other low impedance
applications. The AD8646 and AD8648 are available for
automotive applications (see the Ordering Guide).
Applications include portable and low powered instrumenta-
tion, audio amplification for portable devices, portable phone
headsets, barcode 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.
Rev. D
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2006–2010 Analog Devices, Inc. All rights reserved.
AD8646/AD8647/AD8648
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution...................................................................................6
Typical Performance Characteristics ..............................................7
Theory of Operation ...................................................................... 15
Power-Down Operation ............................................................ 15
Multiplexing Operation ............................................................. 15
Outline Dimensions ....................................................................... 16
Ordering Guide .......................................................................... 18
REVISION HISTORY
4/10—Rev. C to Rev. D
Changes to Features Section and General Description Section . 1
Updated Outline Dimensions ....................................................... 16
Changes to Ordering Guide Section ............................................ 18
Revision History: AD8648
10/07—Rev. A to Rev. B
Combined with AD8646 ................................................... Universal
Added AD8647 ................................................................... Universal
Deleted Figure 7 .................................................................................6
Deleted Figure 11...............................................................................7
Deleted Figure 16 and Figure 17 .....................................................8
Deleted Figure 24...............................................................................9
Deleted Figure 27, Figure 28, Figure 31, and Figure 32 ............ 10
6/07—Rev. 0 to Rev. A
Changes to General Description .....................................................1
Updated Outline Dimensions ....................................................... 12
Changes to Ordering Guide .......................................................... 12
1/06—Revision 0: Initial Version
Revision History: AD8646/AD8647/AD8648
2/09—Rev. B to Rev. C
Change to Supply Current Shutdown Mode (AD8647 Only)
Parameter, Table 1............................................................................. 3
Change to Supply Current Shutdown Mode (AD8647 Only)
Parameter, Table 2............................................................................. 5
Added Figure 50; Renumbered Sequentially .............................. 15
Updated Outline Dimensions ....................................................... 16
Changes to Ordering Guide .......................................................... 18
10/07—Revision B: Initial Combined Version
Revision History: AD8646
10/07—Rev. 0 to Rev. B
Combined with AD8648.................................................... Universal
Added AD8647 ................................................................... Universal
Deleted Figure 4 and Figure 7 ......................................................... 7
Deleted Figure 33 ............................................................................ 11
8/07—Revision 0: Initial Version
Rev. D | Page 2 of 20
AD8646/AD8647/AD8648
SPECIFICATIONS
V
SY
= 5 V, V
CM
= V
SY
/2, T
A
= +25
o
C, unless otherwise noted.
Table 1.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Offset Voltage Drift
Input Bias Current
Symbol
V
OS
ΔV
OS
/ΔT
I
B
Conditions
V
CM
= 0 V to 5 V
−40°C < T
A
< +125°C
−40°C < T
A
< +125°C
−40°C < T
A
< +85°C
−40°C < T
A
< +125°C
Input Offset Current
I
OS
−40°C < T
A
< +85°C
−40°C < T
A
< +125°C
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
Input Capacitance
Differential
Common Mode
OUTPUT CHARACTERISTICS
Output Voltage High
V
CM
CMRR
A
VO
C
DIFF
C
CM
V
OH
I
OUT
= 1 mA
−40°C < T
A
< +125°C
I
OUT
= 10 mA
−40°C < T
A
< +125°C
I
OUT
= 1 mA
−40°C < T
A
< +125°C
I
OUT
= 10 mA
−40°C < T
A
< +125°C
Short circuit
At 1 MHz, A
V
= 1
V
SY
= 2.7 V to 5.5 V
−40°C < T
A
< +125°C
Both amplifiers shut down,
V
IN_SDA
and V
IN_SDB
= 0 V
−40°C < T
A
< +125°C
−40°C < T
A
< +125°C
−40°C < T
A
< +125°C
−40°C < T
A
< +125°C
−40°C < T
A
< +125°C (shutdown active)
R
L
= 2 kΩ
+2.0
+0.8
1
1
11
24
74
0.5
1
1
4.98
4.90
4.85
4.70
V
CM
= 0 V to 5 V
R
L
= 2 kΩ, V
O
= 0.5 V to 4.5 V
0
67
104
84
116
2.5
6.7
4.99
4.92
8.4
78
±120
5
63
80
1.5
10
1
20
40
145
200
0.1
Min
Typ
0.6
1.8
0.3
Max
2.5
3.2
7.5
1
50
550
0.5
50
250
5
Unit
mV
mV
μV/°C
pA
pA
pA
pA
pA
pA
V
dB
dB
pF
pF
V
V
V
V
mV
mV
mV
mV
mA
Ω
dB
mA
mA
nA
μA
V
V
μA
nA
V/μs
MHz
Degrees
μs
μs
μs
Output Voltage Low
V
OL
Output Current
Closed-Loop Output Impedance
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current per Amplifier
Supply Current Shutdown Mode
(AD8647 Only)
SHUTDOWN INPUTS (AD8647)
Logic High Voltage (Enabled)
Logic Low Voltage (Power-Down)
Logic Input Current (Per Pin)
Output Pin Leakage Current
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
Phase Margin
Settling Time
Amplifier Turn-On Time (AD8647)
Amplifier Turn-Off Time (AD8647)
I
sc
Z
OUT
PSRR
I
SY
I
SD
2.0
2.5
V
INH
V
INL
I
IN
SR
GBP
Ø
m
t
s
t
on
t
off
To 0.1%
25°C, A
V
= 1, R
L
= 1 kΩ (see Figure 44)
25°C, A
V
= 1, R
L
= 1 kΩ (see Figure 45)
Rev. D | Page 3 of 20
AD8646/AD8647/AD8648
Parameter
NOISE PERFORMANCE
Peak-to-Peak Noise
Voltage Noise Density
Channel Separation
Total Harmonic Distortion Plus Noise
Symbol
e
n
p-p
e
n
CS
THD + N
Conditions
0.1 Hz to 10 Hz
f = 1 kHz
f = 10 kHz
f = 10 kHz
f = 100 kHz
V p-p = 0.1 V, R
L
= 600 Ω, f = 25 kHz, T
A
= 25°C
A
V
= +1
A
V
= −10
Min
Typ
2.3
8
6
−115
−110
0.010
0.021
Max
Unit
μV
nV/√Hz
nV/√Hz
dB
dB
%
%
Rev. D | Page 4 of 20
