sx8724s Semtech Corporation, sx8724s Datasheet - Page 54

• Manufacturer Part Number: sx8724s
• Description: Zoomingadc For Sensing Data Acquisition
• Manufacturer: Semtech Corporation

Revision 1.0
© Semtech
11.3 Linearity
11.3.1 Integral Non-Linearity
The different PGA stages have been designed to find the best compromise between the noise performance, the
integral non-linearity and the power consumption. To obtain this, the first stage has the best noise performance and
the third stage the best linearity performance. For large input signals (small PGA gains, i.e. up to about 50), the noise
added by the PGA is very small with respect to the input signal and the second and third stage of the PGA should be
used to get the best linearity. For small input signals (large gains, i.e. above 50), the noise level in the PGA is important
and the first stage of the PGA should be used.
The following figures show the Integral non linearity for different gain settings over the chip temperature range
11.3.1.1 Gain 1
V
ADVANCED COMMUNICATIONS & SENSING
BATT
-10
-10
10
10
-2
-4
-6
-8
-2
-4
-6
-8
8
6
4
2
0
8
6
4
2
0
=5V; V
-2
-2
INL Gain 1 @ -40°C
INL Gain 1 @ 85°C
-1.5
-1.5
REF
=V
BATT
-1
-1
Figure 35. INL -40°C
Figure 37. INL 85°C
; PGAs disabled; OSR=1024; Nelconv=8; fs=250kHz; Resolution=16bits.
February 2011
-0.5
-0.5
V
V
IN
IN
0
0
[V]
[V]
0.5
0.5
1
1
1.5
1.5
Page 54
2
2
-10
-10
10
10
-2
-4
-6
-8
-2
-4
-6
-8
8
6
4
2
0
8
6
4
2
0
-2
-2
ZoomingADC for sensing data acquisition
INL Gain 1 @ 25°C
INL Gain 1 @ 125°C
-1.5
-1.5
-1
-1
Figure 38. INL 125°C
Figure 36. INL 25°C
-0.5
-0.5
V
V
IN
IN
0
0
[V]
[V]
SX8724S
0.5
0.5
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