Datasheet
Table Of Contents
Output
Load
Supply
ADC
V+
OUT
GND
IN-
IN+
C
BYPASS
0.01 Fm
to
0.1 Fm
+2.7V to +26V
REF
R
1
R
3
R
2
R
4
R
SHUNT
INA199A1, INA199B1
INA199A2, INA199B2
INA199A3, INA199B3
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SBOS469D –MAY 2009–REVISED NOVEMBER 2012
REF INPUT IMPEDANCE EFFECTS
As with any difference amplifier, the INA199 series common-mode rejection ratio is affected by any impedance
present at the REF input. This concern is not a problem when the REF pin is connected directly to most
references or power supplies. When using resistive dividers from the power supply or a reference voltage, the
REF pin should be buffered by an op amp.
In systems where the INA199 output can be sensed differentially, such as by a differential input analog-to-digital
converter (ADC) or by using two separate ADC inputs, the effects of external impedance on the REF input can
be cancelled. Figure 23 depicts a method of taking the output from the INA199 by using the REF pin as a
reference.
Figure 23. Sensing INA199 to Cancel Effects of Impedance on the REF Input
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Product Folder Links: INA199A1 INA199B1 INA199A2 INA199B2 INA199A3 INA199B3