ADC161S626_14 Datasheet, PDF (24/30 Pages) Texas Instruments – ADC161S626 16-Bit, 50 to 250 kSPS, Differential Input, MicroPower ADC

ADC161S626
SNAS468B – SEPTEMBER 2008 – REVISED MAY 2009
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VBR
Bridge
Sensor
100mV Full
Scale
LMP7732
+
-
20 k:
1 k:
2 k:
20 k:
-
1 k:
+
AV = 20 V/V
2 k:
VA
-
+
470 pF
180:
LMP7731
AV = 2 V/V
2 k:
VCM
+3.3V
+5V +3.3V
+ ^VA
VIO
ADC161S626
-
VREF
SCLK
DOUT
CSB
Micro-
Controller
+
4.7 PF
LM4120-2.5
0.1 PF
+5V
+
4.7 PF
Figure 19. Single-Ended Application for a Bridge Sensor
Current Sensing Application
Figure 20 shows an example of interfacing a current transducer to the ADC161S626. The current transducer
converts an input current into a voltage that is converted by the ADC. Since the output voltage of the current
transducer is single-ended and centered around a common-mode voltage (V_CM) of 2.5V, the ADC161S626 is
configured with the output of the transducer driving the non-inverting input and V_CM of the transducer driving the
inverting input. The output of the transducer has an output range of ±2.5V around V_CM of 2.5V. As a result, a
series reference voltage of 2.5V is connected to the ADC161S626. This will allow all of the codes of the
ADC161S626 to be available for the application. This configuration of the ADC161S626 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.
+5V
LM4120-2.5
+ _{10 PF}
+
VREF _ADC161S626
VA
10 PF 0.1 PF
VIO
0.1 PF
IIN
IOUT
OUT
IIN +5V
IOUT V_CM
GND
2.5V + 2.5V +IN
2.5V
-IN
ADC
LTSR-1513¶V
GND
Serial
Interface
SCLK
DOUT
CSB
Figure 20. Interfacing the ADC161S626 to a Current Transducer
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