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ADVANCED COMMUNICATIONS & SENSING
USER GUIDE
SX8724SEVK
Evaluation Kit for SX8724S Data Acquisition System
ACS - Revision 1.0 May 2011
© Semtech Corp.
The “PGA” controls should then look like the picture below.
17.6
ZoomingADC™ Configuration
17.6.1 Zooming on the Signal
As the sensor is supposed to work at the atmospheric pressure (max: 107.8kPa - min: 88.7kPa) we will zoom
on around these values and thus use the maximum amplification as possible to get the full signal at the ADC
input.
As for zoom in pictures we set a particular zone of interest called measuring window (in red below).
17.6.2 Gain Computing
To compute the total gain that must be applied to the sensor output signal we must know 2 parameters:
1. The maximum output span of the ADC, here 3.3V
2. The maximum output span value of the sensor in the measuring window, here around 8.5-4.5 = 4mV
Figure 37. SX8724S “PGA” Group of Controls Configuration
Figure 38. Zooming on the Signal
ADC input sensor voltage vs pressure
0
200
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600
800
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1400
1600
1800
Pressure [kPa]
Vo
lt
ag
e[mV
D
C
]
Min
Typ
Max
-2
0
2
4
6
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16
Pressure [kPa]
Ou
tp
u
t V
o
lt
ag
e [
m
V
D
C
]
Min
Typ
Max
Sensor output Voltage vs Pressure @ 3.3V supply
89
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93
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97
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103
105
107
0
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Measuring window
Measuring window
