sx8724s Semtech Corporation, sx8724s Datasheet - Page 22

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

Revision 1.0
© Semtech
where GD
7.5 Second Stage Programmable Gain Amplifier (PGA2)
The second PGA has a finer gain and offset tuning capability, as shown in
PGA2 is given by:
where GD
Pga2Gain[1:0] and Pga2Offset[3:0].
7.6 Third Stage Programmable Gain Amplifier (PGA3)
The finest gain and offset tuning is performed with the third and last PGA stage, according to the coding of
ADVANCED COMMUNICATIONS & SENSING
1
2
and GD
is the gain of PGA1 (in V/V) controlled with the Pga1Gain bit.
OFF2
Pga2Gain bit field
Pga3Gain bit field
(RegACCfg2[5:4])
(RegACCfg3[6:0])
are respectively the gain and offset of PGA2 (in V/V). These are controlled with the words
February 2011
0000000
0000001
00
01
10
11
(RegACCfg3[7])
Table 12. PGA3 Gain and Offset Settings
V
Table 11. PGA2 gain and offset settings
Pga1Gain bit
D
PGA2 gain [V/V]
2
1/12 (=0.083)
PGA3 Gain
GD
GD
=
Table 10. PGA1 gain settings
0
1
GD
2
3
10
1
2
5
0
[V/V]
[V/V]
2
⋅
V
D
Page 22
Equation 6
1
−
GDoff
Pga2Offset bit field
Pga3Offset bit field
2
(RegACCfg2[3:0])
(RegACCfg4[6:0])
⋅
ZoomingADC for sensing data acquisition
S
PGA1 gain [V/V]
0000000
0000001
⋅
V
0000
0001
0010
0011
0100
0101
1000
1001
1010
1011
1100
1101
GD
REF
1
10
Table
1
[V/V]
[
V
]
11. The V
+1/12 (=0.083)
GD
GD
PGA3 Offset
PGA2 offset
OFF3
OFF2
+0.2
+0.4
+0.6
+0.8
-0.2
-0.4
-0.6
-0.8
-1.0
D2
+1
0
0
0
[V/V]
[V/V]
voltage at the output of
SX8724S
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DATASHEET
Table
12.