
High Common-Mode Voltage,
Difference Amplifier
AD629
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibilityis assumedbyAnalogDevicesforitsuse,norforanyinfringements of patents or other
rightsofthirdpartiesthatmayresultfromitsuse.Specificationssubjecttochangewithoutnotice.No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
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
1999-2011 Analog Devices, Inc. All rights reserved.
FEATURES
Improved replacement for: INA117P and INA117KU
±270 V common-mode voltage range
Input protection to
±500 V common mode
±500 V differential mode
Wide power supply range (±2.5 V to ±18 V)
±10 V output swing on ±12 V supply
1 mA maximum power supply current
HIGH ACCURACY DC PERFORMANCE
3 ppm maximum gain nonlinearity (AD629B)
20 μV/°C maximum offset drift (AD629A)
10 μV/°C maximum offset drift (AD629B)
10 ppm/°C maximum gain drift
EXCELLENT AC SPECIFICATIONS
77 dB minimum CMRR @ 500 Hz (AD629A)
86 dB minimum CMRR @ 500 Hz (AD629B)
500 kHz bandwidth
APPLICATIONS
High voltage current sensing
Battery cell voltage monitors
Power supply current monitors
Motor controls
Isolation
FUNCTIONAL BLOCK DIAGRAM
1
2
3
4
8
7
6
5
21.1k
380k
20k
REF(–)
–IN
+IN
–VS
NC
+VS
OUTPUT
REF(+)
AD629
NC = NO CONNECT
0
078
3-
0
01
Figure 1.
GENERAL DESCRIPTION
The AD629 is a difference amplifier with a very high input,
common-mode voltage range. It is a precision device that allows
the user to accurately measure differential signals in the
presence of high common-mode voltages up to ±270 V.
The AD629 can replace costly isolation amplifiers in
applications that do not require galvanic isolation. The device
operates over a ±270 V common-mode voltage range and has
inputs that are protected from common-mode or differential
mode transients up to ±500 V.
The AD629 has low offset, low offset drift, low gain error drift,
low common-mode rejection drift, and excellent CMRR over a
wide frequency range.
The AD629 is available in die and packaged form featuring
8-lead PDIP and 8-lead SOIC packages. For all packages
(including die) and grades, performance is guaranteed over
the industrial temperature range of 40°C to +85°C.
FREQUENCY (Hz)
CO
M
O
N
-M
O
D
E
RE
JE
CT
IO
N
R
A
TI
O
(
d
B
)
100
50
55
60
65
70
75
80
85
90
95
20
100
1k
10k
20k
00
78
3-
0
02
Figure 2. Common-Mode Rejection Ratio vs. Frequency
COMMON-MODE VOLTAGE (V)
O
U
T
P
UT
E
RRO
R
(
2mV
/D
IV
)
–240
240
120
–120
0
00
78
3-
0
03
2mV/DIV
60V/DIV
Figure 3. Error Voltage vs. Input Common-Mode Voltage