SX8723 View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'SX8723' PDF : 53 Pages View PDF
SX8723
ZoomingADC™ for Pressure and Temperature Sensing
ADVANCED COMMUNICATIONS & SENSING
The equivalent LSB size at the input of the PGA chain is:
LSB
=
1
2n
⋅ VREF , ADC
GDTOT
⋅ OSR
OSR +1
(V)
Equation 19
Notice that the input voltage VIN,ADC of the ADC must satisfy the condition:
( ) VIN ,ADC
≤
1
2
⋅
VREFP
− VREFN
⋅ OSR
OSR +1
(V)
Equation 20
to remain within the ADC input range.
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 IB_AMP_PGA[1:0] and IB_AMP_ADC[1:0] (see Table 17). If the system is idle, the PGAs and
ADC can even be disabled, thus, reducing power consumption to its minimum. This can considerably improve
battery life.
IB_AMP_ADC[1:0]
(RegACCfg1[7:6])
00
01
11
x
IB_AMP_PGA[1:0]
(RegACCfg1[5:4])
x
00
01
11
ADC Bias Current
1/4⋅IADC
1/2⋅ IADC
IADC
x
PGA Bias Current
x
1/4⋅IPGA
1/2⋅ IPGA
IPGA
Max. fs [kHz]
125
250
500
125
250
500
Table 17 - ADC & PGA Power Saving Modes and Maximum Sampling Frequency
V1.5 © 2007 Semtech Corp.
27
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