Datasheet
+
ADC122S625
V
REF
CHA+
CHA-
GND
V
A
SCLK
D
OUT
0.1 PF
10 PF
0.1 PF
+
10 PF
+5V
CHB-
CHB+
CSB
V
CM
OUT
+5V
GND
I
IN
I
OUT
2.5V
2.5V + 2.0V
I
IN
I
OUT
V
CM
OUT
+5V
GND
I
IN
I
OUT
2.5V
2.5V + 2.0V
I
IN
I
OUT
LTSR-15NPs
LM4132-2.0
ADC
ADC
Serial
Interface
2 k:
+
ADC122S625
V
REF
CHA+
CHA-
GND
V
A
SCLK
D
OUT
0.1 PF
10 PF
0.1 PF
+
10 PF
+5V
Microcontroller
LM4040-2.5
CHB-
CHB+
CSB
DIFFINA
DIFFINB
ADC122S625
SNAS451A –FEBRUARY 2008–REVISED MARCH 2013
www.ti.com
APPLICATION CIRCUITS
The following figures are examples of the ADC122S625 in typical application circuits. These circuits are basic
and will generally require modification for specific circumstances.
Data Acquisition
Figure 38 shows a basic low cost, low power data acquisition circuit. The analog supply pin is powered by the
system +5V supply and the 2.5V reference voltage is generated by the LM4040-2.5 shunt reference.
Figure 38. Low cost, low power Data Acquisition System
Current Sensing Application
Figure 39 shows an example of interfacing a pair of current transducers to the ADC122S625. The current
transducers convert an input current into a voltage that is converted by the ADC122S625. Since the output
voltage of the current transducers are single-ended and centered around a common-mode voltage of 2.5V, the
ADC122S625 is configured with the output of the transducer driving the non-inverting inputs and the common-
mode output voltage of the transducer driving the inverting input. The output of the transducer has an output
range of ±2V around the common-mode voltage of 2.5V. As a result, a series reference voltage of 2.0V is
connected to the ADC122S625. This will allow all of the codes of the ADC122S625 to be available for the
application. This configuration of the ADC122S625 is referred to as a single-ended application of a differential
ADC. All of the elements in the application are conveniently powered by the same +5V power supply, keeping
circuit complexity and cost to a minimum.
Figure 39. Interfacing the ADC122S625 to a Current Transducer
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