AD627ARZ Analog Devices Inc, AD627ARZ Datasheet - Page 11

• Manufacturer Part Number: AD627ARZ
• Description: IC AMP INST R-R 25MA 8SOIC
• Manufacturer: Analog Devices Inc
• Type: Rail-to-Railr

Specifications of AD627ARZ

• Slew Rate: 0.06 V/µs
• Amplifier Type: Instrumentation
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• -3db Bandwidth: 80kHz
• Current - Input Bias: 2nA
• Voltage - Input Offset: 25µV
• Current - Supply: 60µA
• Current - Output / Channel: 25mA
• Voltage - Supply, Single/dual (±): 2.2 V ~ 36 V, ±1.1 V ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• No. Of Amplifiers: 1
• Input Offset Voltage: 200µV
• Gain Db Min: 5dB
• Gain Db Max: 1000dB
• Bandwidth: 40MHz
• Amplifier Output: Rail To Rail
• Cmrr: 77dB
• Supply Voltage Range: ± 1.1V To ±
• Common Mode Rejection Ratio: 90
• Current, Input Bias: 3 nA (Single), 2 nA (Dual)
• Current, Input Offset: 0.3 nA
• Current, Supply: 60 μA
• Impedance, Thermal: 155 °C/W
• Package Type: SOIC-8
• Power Dissipation: 0.8 W
• Resistance, Input: 20 Gigaohms (Differential), 20 Gigaohms (Common-Mode)
• Temperature, Operating, Range: -40 to +85 °C
• Voltage, Gain: 1000 V/V
• Voltage, Input: -35.9 to +35 V (Single), -17.9 to +17 V (Dual)
• Voltage, Input Offset: 50 μV (Single), 25 μV (Dual)
• Voltage, Noise: 38 nV/sqrt Hz
• Voltage, Supply: 2.2 to ±18 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Gain Bandwidth Product: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

V
± 100 mV, V
± 50 mV, V
± 10 mV, V
V– = 0 V, V+ = 0 V to 1 V
V– = 0 V, V+ = 0 mV to 100 mV
V– = 0 V, V+ = 0 mV to 10 mV
Desired
Gain
5
6
7
8
9
10
15
20
25
30
40
50
60
70
80
90
100
200
500
1000
Reference Terminal
The reference terminal potential defines the zero output voltage
and is especially useful when the load does not share a precise
ground with the rest of the system. It provides a direct means of
injecting a precise offset to the output. The reference terminal is
also useful when bipolar signals are being amplified as it can be
used to provide a virtual ground voltage.
Since the AD627 output voltage is developed with respect to the
potential on the reference terminal, it can solve many grounding
problems by simply tying the REF pin to the appropriate “local
ground.” The REF pin should however be tied to a low imped-
ance point for optimal CMR.
IN
Table I. Recommended Values of Gain Resistors
CM
CM
CM
= 0 V
= 0 V
= 0 V
V
CM
1% Std Table
Value of R
∞
200 k
100 k
68.1 k
51.1 k
40.2 k
20 k
13.7 k
10 k
8.06 k
5.76 k
4.53 k
3.65 k
3.09 k
2.67 k
2.37 k
2.1 k
1.05 k
412
205
Table II. Maximum Gain for Low Common-Mode Single Supply Applications
V
V
DIFF
DIFF
2
2
G
V+
V–
,
+IN
–IN
2 V
2 V
2 V
1 V
1 V
REF
Pin
1 V
REF
–IN
2k
Resulting
Gain
5.00
6.00
7.00
7.94
8.91
9.98
15.00
19.60
25.00
29.81
39.72
49.15
59.79
69.72
79.91
89.39
100.24
195.48
490.44
980.61
Supply
Voltage
5 V to 15 V
5 V to 15 V
5 V to 15 V
10 V to 15 V
5 V to 15 V
5 V to 15 V
100k
+V
–V
S
S
Q1
EXTERNAL GAIN RESISTOR
200k
25k
A1
Input Range Limitations in Single Supply Applications
In general, the maximum achievable gain is determined by the
available output signal range. However, in single supply applica-
tions where the input common-mode voltage is close to or equal
to zero, some limitations on the gain can be set. While the Input,
Output and Reference Pins have ranges that are nominally defined
on the specification pages, there is a mutual interdependence
between the voltage ranges on these pins. Figure 4 shows the
simplified schematic of the AD627, driven by a differential
voltage V
voltage on the output of op amp A1 is a function of V
the voltage on the REF pin and the programmed gain. This
voltage is given by the equation:
We can also express the voltage on A1 as a function of the actual
voltages on the –IN and +IN pins (V– and V+)
A1’s output is capable of swinging to within 50 mV of the nega-
tive rail and to within 200 mV of the positive rail. From either of
the above equations, it is clear that an increasing V
acts as a positive offset at the output of the AD627), tends to
decrease the voltage on A1. Figures 5 and 6 show the maximum
voltages that can be applied to the REF pin, for a gain of five for
both the single and dual supply cases. Raising the input com-
mon-mode voltage will increase the voltage on the output of A1.
However, in single supply applications where the common-
mode voltage is low, a differential input voltage or a voltage on
REF that is too high can drive the output of A1 into the ground
rail. Some low side headroom is added by virtue of both inputs
being shifted upwards by about 0.5 V (i.e., by the V
and Q2). The above equations can be used to check that the
voltage on amplifier A1 is within its operating range.
Table II gives values for the maximum gains for various single
supply input conditions. The resulting output swings shown
refer to 0 V. The voltages on the REF pins has been set to either
V
A1
V
A1
R
0.1V
= 1.25 (V
G
= 1.25 (V– + 0.5 V) – 0.25 V
R
Tolerance)
28.7 kΩ
10.7 kΩ
1.74 kΩ
78.7 kΩ
7.87 kΩ
7.87 Ω
G
25k
DIFF
V
(1%
A
Q2
which has a common-mode component, V
CM
200k
+ 0.5 V) – 0.25 V
+V
–V
S
S
100k
2k
A2
Resulting
Max Gain
12.0
23.7
119.9
7.5
31
259.1
+IN
REF
REF
OUTPUT
–V
– V
S
– (V+ – V–) 25 kΩ/R
DIFF
(25 kΩ/R
Output Swing
WRT 0 V
0.8 V to 3.2 V
0.8 V to 3.2 V
0.8 V to 3.2 V
1 V to 8.5 V
1 V to 4.1 V
1 V to 3.6 V
AD627
REF
DIFF
, (while it
BE
G
– 0.625)
CM
of Q1
, V
. The
CM
G
,