sx8725c Semtech Corporation, sx8725c Datasheet - Page 35

• Manufacturer Part Number: sx8725c
• Description: Zoomingadc For Sensing Data Acquisition
• Manufacturer: Semtech Corporation

Revision 1.01
© Semtech
The equivalent LSB size at the input of the PGA chain is:
Notice that the input voltage V
to remain within the ADC input range.
7.7.9 Power Saving Modes
During low-speed operation, the bias current in the PGAs and ADC can be programmed to save power using the
control words IbAmpPga[1:0] and IbAmpAdc[1:0] (see
disabled, thus, reducing power consumption to its minimum. This can considerably improve battery lifetime.
ADVANCED COMMUNICATIONS & SENSING
Table 21. ADC & PGA power saving modes and maximum sampling frequency
IbAmpAdc [1:0]
00
01
11
January 2011
IN,ADC
IbAmpPga [1:0]
of the ADC must satisfy the condition:
V
LSB
IN
00
01
11
,
ADC
=
2
≤
1
n
1
2
⋅
ADC Bias Current PGA Bias Current
GD
⋅
V
Equation 22
Equation 23
(
Table
Page 35
V
REF
1/4 x I
1/2 x I
TOT
REFP
I
ADC
⋅
21). If the system is idle, the PGAs and ADC can even be
−
ADC
ADC
OSR
V
OSR
REFN
ZoomingADC for sensing data acquisition
+
1
)
⋅
OSR
[
V
OSR
1/4 x I
1/2 x I
/
I
PGA
V
+
PGA
PGA
]
1
Max. fs [kHz]
www.semtech.com/products/
125
250
500
125
250
500
SX8725C
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