xe8802 Semtech Corporation, xe8802 Datasheet - Page 128

• Manufacturer Part Number: xe8802
• Description: Data Acquisition Soc With 16+10 Bit Zoomingadc? Embedded Risc Controller And Lcd Driver
• Manufacturer: Semtech Corporation

to remain within the ADC input range.
17.7.8
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 17-26). 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 lifetime.
17.8 Specifications and Measured Curves
This section presents measurement results for the acquisition chain. A summary table with circuit specifications
and measured curves are given.
17.8.1
Unless otherwise specified, the measurement conditions are the following:
© Semtech 2006
V
IN
Power Saving Modes
Default Settings
,
ADC
≤
Temperature T
V
RC frequency f
Offsets GDOff
Power operation: normal (IB_AMP_ADC[1:0] = IB_AMP_PGA[1:0] = '11')
Resolution:
Table 17-26. ADC & PGA power saving modes and maximum sampling frequency
DD
1
2
⋅
= +5V, GND = 0V, V
(
V
REFP
IB_AMP_ADC
[1:0]
−
V
00
01
10
11
x
REFN
2
A
RC
= GDOff
for n = 12 bits: OSR = 32 and N
= +25°C
)
= 2MHz, sampling frequency f
⋅
OSR
o
OSR
IB_AMP_PGA
3
+
for n = 16 bits: OSR = 512 and N
[1:0]
REF
= 0
1
00
01
10
11
XE8802 Sensing Machine Data Acquisition MCU
x
= +5V, V
(V)
1/4⋅I
1/2⋅I
3/4⋅I
Current
IN
ADC
Bias
I
ADC
17-16
= 0V
x
ADC
ADC
ADC
with ZoomingADC™ and LCD driver
Current
1/4⋅I
1/2⋅I
3/4⋅I
PGA
Bias
I
ELCONV
S
PGA
x
= 500kHz
PGA
PGA
PGA
= 4
Max. f
(Eq. 20)
[kHz]
62.5
62.5
125
250
500
125
250
500
ELCONV
S
= 2
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