Analog Devices AD8648 Service Manual
Low Cost, 24 MHz, Rail-to-Rail,
O
O
FEATURES
Low offset voltage: 2.5 mV max
Single-supply operation: 2.7 V to 5.5 V
Low noise: 6 nV/√Hz
Wide bandwidth: 24 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 max
Unity-gain stable
APPLICATIONS
Barcode scanners
Battery-powered instrumentation
Multipole filters
Sensors
ASIC input or output amplifiers
Audio
Photodiode amplification
GENERAL DESCRIPTION
Quad Amplifiers
AD8648
PIN CONFIGURATIONS
1
1
UT A 14
2
2
–IN A
3
3
+IN A
+IN B
–IN B
UT B
V+
AD8648
AD8648
TOP VIEW
TOP VIEW
4
4
(Not to Scale)
(Not to Scale)
5
5
6
6
7
7
Figure 1. 14-Lead TSSOP (RU-14)
OUT A
1
1
2
2
–IN A
+IN A
3
3
AD8648
AD8648
TOP VIEW
TOP VIEW
V+
4
4
(Not to Scale)
(Not to Scale)
5
5 10
+IN B
–IN B
6
6 9
7
7 8
OUT B
Figure 2. 14-Lead SOIC (R-14)
14
14
13
13
12
12
11
11
10
14
13
13
12
12
11
11
10
10
9
9
8
8
9
8
OUT D
–IN D
+IN D
V–
+IN C
–IN C
OUT C
OUT D
–IN D
+IN D
V–
+IN C
–IN C
OUT C
05890-001
5890-002
The AD8648 is a quad, rail-to-rail, input and output, singlesupply amplifier featuring low offset voltage, wide signal
bandwidth, and low input voltage and current noise.
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. The AD8648
family offers high output drive capability, which is excellent for
audio line drivers and other low impedance applications.
Applications for the part 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.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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 Analog Devices, Inc. All rights reserved.
AD8648
TABLE OF CONTENTS
Features.............................................................................................. 1
Absolute Maximum Ratings ............................................................5
Applications....................................................................................... 1
Pin Configurations ........................................................................... 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications..................................................................................... 3
REVISION HISTORY
1/06—Rev 0: Initial Version
Thermal Resistance.......................................................................5
ESD Caution...................................................................................5
Typical Performance Characteristics..............................................6
Outline Dimensions....................................................................... 12
Ordering Guide .......................................................................... 12
Rev. 0 | Page 2 of 12
AD8648
SPECIFICATIONS
VDD = 5.0 V, VCM = VDD/2, TA = 25oC, unless otherwise noted.
Table 1.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage V
OS
−40°C < TA < +125°C 3.2 mV
Offset Voltage Drift ΔVOS/ΔT −40°C < TA < +125°C 2.0 7.5 μV/°C
Input Bias Current I
B
−40°C < TA < +85°C 50 pA
−40°C < TA < +125°C 550 pA
Input Offset Current I
OS
−40°C < TA < +85°C 50 pA
−40°C < TA < +125°C 250 pA
Input Voltage Range V
CM
Common-Mode Rejection Ratio CMRR VCM = 0 V to 5.0 V 67 84 dB
Large-Signal Voltage Gain AVO R
Input Capacitance C
C
DIFF
CM
OUTPUT CHARACTERISTICS
Output Voltage High V
OH
I
−40°C < TA < +125°C 4.70 V
Output Voltage Low V
OL
I
−40°C < TA < +125°C 200 mV
Short-Circuit Output Current I
Closed-Loop Output Impedance Z
SC
OUT
POWER SUPPLY
Power Supply Rejection Ratio PSRR VDD = 2.7 V to 5.5 V 63 80 dB
Supply Current per Amplifier ISY 1.8 2.0 mA
−40°C < TA < +125°C 2.5 mA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 12 V/μs
Settling Time ts To 0.01% 0.5 μs
Gain Bandwidth Product GBP 24 MHz
Phase Margin Φ
M
NOISE PERFORMANCE
Peak-to-Peak Noise en p-p 0.1 Hz to 10 Hz 2.4 μV
Voltage Noise Density e
n
f = 10 kHz 6 nV/√Hz
Channel Separation CS f = 10 kHz −115 dB
f = 100 kHz −110 dB
VCM = 0 V to 5 V 0.7 2.5 mV
0.2 1 pA
0.1 0.5 pA
0 5 V
= 2 kΩ, VO = 0.5 V to 4.5 V 160 700 V/mV
L
2.5 pF
6.7 pF
I
= 1 mA 4.98 4.99 V
OUT
= 10 mA 4.87 4.92 V
OUT
I
= 1 mA 8.4 20 mV
OUT
= 10 mA 78 145 mV
OUT
±150 mA
At 1 MHz, AV = 1 3 Ω
74 Degrees
f = 1 kHz 8 nV/√Hz
Rev. 0 | Page 3 of 12
AD8648
VDD = 2.7 V, VCM = VDD/2, TA = 25oC, unless otherwise noted.
Table 2.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage V
OS
−40°C < TA < +125°C 3.2 mV
Offset Voltage Drift ΔVOS/ΔT −40°C < TA < +125°C 1.8 7.0 μV/°C
Input Bias Current I
B
−40°C < TA < +85°C 50 pA
−40°C < TA < +125°C 550 pA
Input Offset Current I
OS
−40°C < TA < +85°C 50 pA
−40°C < TA < +125°C 250 pA
Input Voltage Range V
CM
Common-Mode Rejection Ratio CMRR VCM = 0 V to 2.7 V 62 79 dB
Large-Signal Voltage Gain AVO R
Input Capacitance C
C
DIFF
CM
OUTPUT CHARACTERISTICS
Output Voltage High V
OH
−40°C < TA < +125°C 2.60 V
Output Voltage Low V
OL
−40°C < TA < +125°C 30 mV
Short-Circuit Output Current I
Closed-Loop Output Impedance Z
SC
OUT
POWER SUPPLY
Power Supply Rejection Ratio PSRR VDD = 2.7 V to 5.5 V 63 80 dB
Supply Current per Amplifier ISY 1.7 2.0 mA
−40°C < TA < +125°C 2.5 mA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 2 kΩ 12 V/μs
Settling Time ts To 0.01% 0.3 μs
Gain Bandwidth Product GBP 22 MHz
Phase Margin Φ
M
NOISE PERFORMANCE
Peak-to-Peak Noise en p-p 0.1 Hz to 10 Hz 2.1 μV
Voltage Noise Density e
n
f = 10 kHz 6 nV/√Hz
Channel Separation CS f = 10 kHz −115 dB
f = 100 kHz −110 dB
VCM = 0 V to 2.7 V 0.7 2.5 mV
0.2 1 pA
0.1 0.5 pA
0 2.7 V
= 2 kΩ, VO = 0.5 V to 2.2 V 60 130 V/mV
L
2.5 pF
7.8 pF
I
= 1 mA 2.65 2.69 V
OUT
I
= 1 mA 11 25 mV
OUT
±50 mA
At 1 MHz, AV = 1 3 Ω
52 Degrees
f = 1 kHz 8 nV/√Hz
Rev. 0 | Page 4 of 12
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