Datasheet

+
-
+
-
ADC_A
100 k:
Bridge
Sensor
+5V
A
V
= 100 V/V
100 k:
2 k:
180 :
180 :
470 pF
+5V
+5V = V
A
,V
D
LM4132-4.1
4.7 PF
+
+
4.7 PF
+
-
+
-
ADC_B
V
REF
LMP7704
100 k:
Bridge
Sensor
+5V
A
V
= 100 V/V
100 k:
2 k:
180 :
180 :
470 pF
Serial Interface
DOUTB
SCLK
DOUTA
CSB
0.1 PF
ADC122S706
ADC122S706
SNAS408A –NOVEMBER 2007–REVISED MARCH 2013 www.ti.com
Bridge Sensor Application
Figure 50 shows an example of interfacing the ADC122S706 to a pair of bridge sensors. The application
assumes that the bridge sensors require buffering and amplification to fully utilize the dynamic range of the ADC
and thus optimize the performance of the entire signal path. The amplification stage for each ADC input consists
of a pair of opamps from the LMP7704. The amplification stage offers the benefit of high input impedance and
potentially high amplification. On the other hand, it offers no common-mode rejection of noise coming from the
bridge sensors. The application circuit assumes the bridge sensors are powered from the same +5V power
supply voltage as the analog supply pin on the ADC122S706. This has the benefit of providing the ideal
common-mode input voltage for the ADC122S706 while keeping design complexity and cost to a minimum. The
LM4132-4.1, a 4.1V series reference, is used as the reference voltage in the application.
Figure 50. Interfacing the ADC122S706 to Bridge Sensors
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Product Folder Links: ADC122S706