AD629AR-REEL7 Analog Devices Inc, AD629AR-REEL7 Datasheet - Page 12

• Manufacturer Part Number: AD629AR-REEL7
• Description: IC,VOLT FOLLOWER,SINGLE,SOP,8PIN,PLASTIC
• Manufacturer: Analog Devices Inc

Specifications of AD629AR-REEL7

• Rohs Status: RoHS non-compliant
• Design Resources: Measuring -48 V High-Side Current Using AD629, AD8603, AD780, and AD7453 (CN0100)
• Amplifier Type: Differential
• Number Of Circuits: 1
• Slew Rate: 2.1 V/µs
• -3db Bandwidth: 500kHz
• Voltage - Input Offset: 200µV
• Current - Supply: 900µA
• Current - Output / Channel: 25mA
• Voltage - Supply, Single/dual (±): 5 V ~ 36 V, ±2.5 V ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Output Type: -
• Gain Bandwidth Product: -
• Current - Input Bias: -

AD629
OUTPUT CURRENT AND BUFFERING
The AD629 is designed to drive loads of 2 kΩ to within 2 V of
the rails but can deliver higher output currents at lower output
voltages (see Figure 15). If higher output current is required, the
output of the AD629 should be buffered with a precision op amp,
such as the OP113, as shown in Figure 36. This op amp can swing
to within 1 V of either rail while driving a load as small as 600 Ω.
A GAIN OF 19 DIFFERENTIAL AMPLIFIER
While low level signals can be connected directly to the –IN and
+IN inputs of the AD629, differential input signals can also be
connected, as shown in Figure 37, to give a precise gain of 19.
However, large common-mode voltages are no longer permissible.
Cold junction compensation can be implemented using a
temperature sensor, such as the AD590.
Table 5. AD629 vs. INA117 Error Budget Analysis Example 1 (V
Error Source
ACCURACY, T
TEMPERATURE DRIFT (85°C)
RESOLUTION
Initial Gain Error
Offset Voltage
DC CMR (Over Temperature)
Gain
Offset Voltage
Noise, Typical, 0.01 Hz to 10 Hz, μV p-p
CMR, 60 Hz
Nonlinearity
–V
THERMOCOUPLE
0.1µF
S
–IN
+IN
REF (–)
Figure 37. A Gain of 19 Thermocouple Amplifier
A
1
2
3
4
= 25°C
NC = NO CONNECT
Figure 36. Output Buffering Application
21.1kΩ
380kΩ
380kΩ
V
AD629
REF
380kΩ
20kΩ
REF (–)
+IN
–IN
8
7
6
5
1
2
3
4
NC = NO CONNECT
NC
REF (+)
21.1kΩ
380kΩ
380kΩ
0.1µF
AD629
380kΩ
20kΩ
OP113
+V
–V
S
S
8
7
6
5
0.1µF
0.1µF
AD629
(0.0005 × 10)/10 V × 10
(0.001 V/10 V) × 10
(224 × 10
10 ppm/°C × 60°C
(20 μV/°C × 60°C) × 10
(141 × 10
(10
15 μV/10 V × 10
NC
+V
REF (+)
S
-5
× 10 V)/10 V × 10
+V
0.1µF
S
V
V
-6
-6
OUT
OUT
× 200 V)/10 V × 10
× 1 V)/10 V × 10
Rev. B | Page 12 of 16
6
6
CM
6
6
/10 V
6
= 200 V dc)
6
ERROR BUDGET ANALYSIS EXAMPLE 1
In the dc application that follows, the 10 A output current from
a device with a high common-mode voltage (such as a power
supply or current-mode amplifier) is sensed across a 1 Ω shunt
resistor (see Figure 38). The common-mode voltage is 200 V,
and the resistor terminals are connected through a long pair of
lead wires located in a high noise environment, for example,
50 Hz/60 Hz, 440 V ac power lines. The calculations in Table 5
assume an induced noise level of 1 V at 60 Hz on the leads, in
addition to a full-scale dc differential voltage of 10 V. The error
budget table quantifies the contribution of each error source.
Note that the dominant error source in this example is due to
the dc common-mode voltage.
SHUNT
6
CURRENT
1Ω
OUTPUT
V
Figure 38. Error Budget Analysis Example 1: V
CM
= 200 V DC, R
10 AMPS
200V
TO GROUND
INA117
(0.0005 × 10)/10 V × 10
(0.002 V/10 V) × 10
(500 × 10
Total Accuracy Error
10 ppm/°C × 60°C
(40 μV/°C × 60°C) × 10
Total Drift Error
25 μV/10 V × 10
(500 × 10
(10
Total Resolution Error
Total Error
POWER LINE
-5
CM
× 10 V)/10 V × 10
60Hz
DC
-6
-6
SHUNT
× 200 V)/10 V × 10
× 1 V)/10 V × 10
–V
= 1 Ω, 1 V p-p, 60 Hz Power-Line Interference
6
S
REF (–)
6
+IN
0.1µF
–IN
6
6
/10 V
6
1
2
3
4
NC = NO CONNECT
21.1kΩ
380kΩ
380kΩ
6
6
AD629
380kΩ
20kΩ
IN
AD629
500
100
4480
5080
600
120
720
2
14
10
26
5826
= 10 V Full-Scale,
Error, ppm of FS
8
7
6
5
NC
REF (+)
INA117
500
200
10,000
10,700
600
240
840
3
50
10
63
11,603
0.1µF
V
OUT
+V
S