High Common-Mode Voltage,
Difference Amplifier
AD629
Rev. C
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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
21.1kΩ
380kΩ
380kΩ
380kΩ
20kΩ
REF(–)
–IN
+IN
–V
S
NC
+V
S
OUTPUT
REF(+)
AD629
NC = NO CONNECT
0783-001
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)
COMMON-MODE REJECTION
TIO (dB)
100
50
55
60
65
70
75
80
85
90
95
20 100 1k 10k 20k
00783-002
Figure 2. Common-Mode Rejection Ratio vs. Frequency
COMMON-MODE VOLTAGE (V)
OUTPUT ERROR (2mV/DIV)
–240 240120–120 0
00783-003
2mV/DIV
60V/DIV
Figure 3. Error Voltage vs. Input Common-Mode Voltage
