High Common-Mode Voltage,
Difference Amplifier
AD629
FUNCTIONAL BLOCK DIAGRAM
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
REF(–) 1
–IN 2
+IN 3
–VS
4
380kΩ
21.1kΩ
20kΩ
AD629
NC
+VS
6
380kΩ
8
7
380kΩ
OUTPUT
5
REF(+)
00783-001
FEATURES
NC = NO CONNECT
Figure 1.
GENERAL DESCRIPTION
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
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.
EXCELLENT AC SPECIFICATIONS
77 dB minimum CMRR @ 500 Hz (AD629A)
86 dB minimum CMRR @ 500 Hz (AD629B)
500 kHz bandwidth
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.
APPLICATIONS
High voltage current sensing
Battery cell voltage monitors
Power supply current monitors
Motor controls
Isolation
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.
2mV/DIV
95
OUTPUT ERROR (2mV/DIV)
90
85
80
75
70
65
55
50
20
100
1k
FREQUENCY (Hz)
10k
20k
00783-003
60
00783-002
COMMON-MODE REJECTION RATIO (dB)
100
60V/DIV
–240
–120
0
120
COMMON-MODE VOLTAGE (V)
240
Figure 2. Common-Mode Rejection Ratio vs. Frequency
Figure 3. Error Voltage vs. Input Common-Mode Voltage
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 ©1999-2011 Analog Devices, Inc. All rights reserved.
Rev. C
