Datasheet

NC
+Vs
-Vs
+Vs
-Vs
+Vs
Rg 5k
Vin
Temp
GND
Vout
Trim
U2 REF5025
Rset 2.5k
Rparasitic 5
V1 15
V2 15
-
+
Vout
RTD 100
A
+
Iset
-
+
Vset
VirtualGND
-
+
+
U1 OPA188
R2 1.5M
+
+
-
Rg
Rg
Ref
U4 INA826
Vref5025
+Vs
-Vs
INA826
www.ti.com SBOS562E –AUGUST 2011–REVISED APRIL 2013
Figure 69 shows an example of how the INA826 can be used for RTD signal conditioning. This circuit creates an
excitation current (I
SET
) by forcing +2.5 V from the REF5025 across R
SET
. The zero-drift, low-noise OPA188
creates the virtual ground that maintains a constant differential voltage across R
SET
with changing common-mode
voltage. This voltage is necessary because the voltage on the positive input of the INA826 fluctuates over
temperature as a result of the changing RTD resistance. Click the following link to download the TINA-TI file:
RTD Circuit.
Figure 69. RTD Signal Conditioning
Copyright © 2011–2013, Texas Instruments Incorporated Submit Documentation Feedback 29
Product Folder Links: INA826