SX8723E083TRT View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'SX8723E083TRT' PDF : 53 Pages View PDF
SX8723
ZoomingADC™ for Pressure and Temperature Sensing
ADVANCED COMMUNICATIONS & SENSING
Programmable Gain Amplifiers
As seen in Figure 8, the zooming function is implemented with three programmable gain amplifiers (PGA).
These are:
• PGA1: coarse gain tuning
• PGA2: medium gain and offset tuning
• PGA3: fine gain and offset tuning. Should be set ON for high linearity data acquisition
All gain and offset settings are realized with ratios of capacitors. The user has control over each PGA activation
and gain, as well as the offset of stages 2 and 3. These functions are examined hereafter.
ENABLE[3:0]
(RegACCfg1[3:0])
xxx0
xxx1
xx0x
xx1x
x0xx
x1xx
0xxx
1xxx
Block
ADC disabled
ADC enabled
PGA1 disabled
PGA1 enabled
PGA2 disabled
PGA2 enabled
PGA3 disabled
PGA3 enabled
Table 4 - ADC & PGA Enabling
PGA1_GAIN
(RegACCfg3[7])
0
1
PGA1 Gain
GD1 (V/V)
1
10
Table 5 - PGA1 Gain Settings
PGA2_GAIN[1:0]
(RegACCfg2[5:4])
00
01
10
11
PGA2 Gain
GD2 (V/V)
1
2
5
10
Table 6 - PGA2 Gain Settings
PGA2_OFFSET[3:0]
(RegACCfg2[3:0])
0000
0001
0010
0011
0100
0101
1001
1010
1011
1100
1101
PGA2 Offset
GDoff2 (V/V)
0
+0.2
+0.4
+0.6
+0.8
+1
-0.2
-0.4
-0.6
-0.8
-1
Table 7 - PGA2 Offset Settings
V1.5 © 2007 Semtech Corp.
20
PGA3_GAIN[6:0]
(RegACCfg3[6:0])
0000000
0000001
...
0000110
...
0001100
0010000
...
0100000
...
1000000
...
1111111
PGA3 Gain
GD3 (V/V)
0
1/12(=0.083)
...
6/12
...
12/12
16/12
32/12
64/12
127/12(=10.58)
Table 8 - PGA3 Gain Settings
PGA3_OFFSET[6:0]
(RegACCfg4[6:0])
0000000
0000001
0000010
...
0010000
...
0100000
...
0111111
1000000
1000001
1000010
...
1010000
...
1100000
...
1111111
PGA3 Offset
GDoff3 (V/V)
0
+1/12(=+0.083)
+2/12
...
+16/12
...
+32/12
...
+63/12(=+5.25)
0
-1/12(=-0.083)
-2/12
...
-16/12
...
-32/12
...
-63/12(=-5.25)
Table 9 - PGA3 Offset Settings
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