sx8724s Semtech Corporation, sx8724s Datasheet - Page 23

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

Revision 1.0
© Semtech
The output of PGA3 is also the input of the ADC. Thus, similarly to PGA2, we find that the voltage entering the ADC is
given by:
where GD
Pga3Offset[6:0].
To remain within the signal compliance of the PGA stages (no saturation), the condition:
must be verified.
ADVANCED COMMUNICATIONS & SENSING
3
and GD
OFF3
Pga3Gain bit field
(RegACCfg3[6:0])
are respectively the gain and offset of PGA3 (in V/V). The control words are Pga3Gain[6:0] and
February 2011
0000110
0001100
0010000
0100000
1000000
1111111
...
...
...
...
...
V
Table 12. PGA3 Gain and Offset Settings
IN
,
ADC
127/12 (=10.58)
PGA3 Gain
GD
12/12
16/12
32/12
64/12
=
6/12
3
...
...
...
...
...
[V/V]
GD
V
IN
3
,
⋅
V
V
Page 23
Equation 7
Equation 8
D
D
2
1
,
−
V
GDoff
D
2
<
Pga3Offset bit field
(RegACCfg4[6:0])
V
3
ZoomingADC for sensing data acquisition
BATT
⋅
2
0010000
0100000
0111111
1000000
1000001
1000010
1010000
1100000
1111111
S
⋅
...
...
...
...
...
...
V
REF
[
V
]
+63/12 (=+5.25)
-1/12 (=-0.083)
-63/12 (=-5.25)
GD
PGA3 Offset
+16/12
OFF3
-16/12
-32/12
32/12
-2/12
...
...
0
...
...
...
[V/V]
SX8724S
www.semtech.com
DATASHEET