AD8223ARM Analog Devices Inc, AD8223ARM Datasheet - Page 16

• Manufacturer Part Number: AD8223ARM
• Description: Single Supply Low Cost Intrumentation Am
• Manufacturer: Analog Devices Inc

Specifications of AD8223ARM

• Amplifier Type: Instrumentation
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 0.3 V/µs
• -3db Bandwidth: 200kHz
• Current - Input Bias: 12nA
• Voltage - Input Offset: 250µV
• Current - Supply: 650µA
• Voltage - Supply, Single/dual (±): 3 V ~ 24 V, ±2 V ~ 12 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Peak Reflow Compatible (260 C): No
• Rohs Compliant: No
• Input Offset Voltage: 250µV
• Bandwidth: 200kHz
• Amplifier Output: Rail To Rail
• Cmrr: 90dB
• Supply Current: 350µA
• Amplifier Case Style: MSOP
• No. Of Pins: 8
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Output / Channel: -
• Gain Bandwidth Product: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant, Contains lead / RoHS non-compliant

AD8223
GROUND RETURNS FOR INPUT BIAS CURRENTS
Input bias currents are those dc currents that must flow to bias
the input transistors of an amplifier. These are usually transistor
base currents. When amplifying floating input sources such as
transformers or ac-coupled sources, there must be a direct dc
path into each input so that the bias current can flow. Figure 35
shows how a bias current path can be provided for the cases of
transformer coupling, capacitive ac-coupling, and a thermo-
couple application.
In dc-coupled resistive bridge applications, providing this path
is generally not necessary because the bias current simply flows
from the bridge supply through the bridge and into the amplifier.
However, if the impedances that the two inputs see are large and
differ by a large amount (>10 kΩ), the offset current of the input
stage causes dc errors proportional to the input offset voltage of
the amplifier.
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CAPACITIVELY COUPLED
C
C
THERMOCOUPLE
TRANSFORMER
INCORRECT
AD8223
+V
–V
AD8223
AD8223
+V
–V
+V
–V
S
S
S
S
S
S
REF
Figure 35. Creating an I
REF
REF
f
HIGH-PASS
=
2πRC
1
10MΩ
CAPACITIVELY COUPLED
BIAS
C
C
Path
THERMOCOUPLE
TRANSFORMER
R
R
CORRECT
AD8223
AD8223
AD8223
+V
+V
+V
–V
–V
–V
S
S
S
S
S
S
REF
REF
REF