SX8722I070LF SEMTECH [Semtech Corporation], SX8722I070LF Datasheet - Page 61

• Manufacturer Part Number: SX8722I070LF
• Description: High gain acquisition for sensor interface
• Manufacturer: SEMTECH [Semtech Corporation]

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 GD3 and GDoff3 are respectively the gain and offset of PGA3 (in V/V). The control words are PGA3_GAIN[6:0] and
PGA3_OFFSET[6:0] . To remain within the signal compliance of the PGA stages, the condition:
must be verified.
Finally, combining equations Eq. 5 to Eq. 7 for the three PGA stages, the input voltage V
by:
ACS - Revision 4.2
©2008 Semtech Corp.
ADVANCED COMMUNICATIONS & SENSING
V
IN
V
,
IN
ADC
,
ADC
=
=
GD
GD
V
TOT
D
1
3
,
(Eq. 7)
(Eq. 8)
(Eq. 9)
V
⋅
⋅
V
V
D
D
IN
2
2
<
−
−
V
GDoff
GDoff
DD
October 2008
TOT
3
⋅
V
PGA3_GAIN[6:0]
⋅
REF
V
REF
Table 48. PGA3 offset settings
1000000
1000001
1000010
1010000
1100000
1111111
...
...
...
V [ ]
V [ ]
V [ ]
Page 61
PGA3 gain [V/V]
-1/12(=-0.083)
-63/12(=5.25)
-16/12
-32/12
High gain acquisition for sensor interface
-2/12
...
...
...
0
IN,ADC
of the ADC is related to V
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IN