XE8805 SEMTECH [Semtech Corporation], XE8805 Datasheet - Page 100

• Manufacturer Part Number: XE8805
• Description: Data Acquisition MCU
• Manufacturer: SEMTECH [Semtech Corporation]

16.7.2
The word FIN[1:0] is used to select the sampling frequency f
RC-based frequency f
information on oscillators and their control can be found in the clock block documentation.
16.7.3
The over-sampling ratio (OSR) defines the number of integration cycles per elementary conversion. Its value is set
with the word SET_OSR[2:0] in power of 2 steps (see Table 16-20) given by:
16.7.4
As mentioned previously, the whole conversion sequence is made of a set of N
conversions. This number is set with the word SET_NELC[1:0] in power of 2 steps (see Table 16-21) given by:
© Semtech 2006
OSR
N
ELCONV
Sampling Frequency
Over-Sampling Ratio
Elementary Conversions
=
2
3
=
+
2
SET_OSR[2
SET_NELC[1
RCEXT
Table 16-19. Sampling frequency settings (f
:
can be chosen. For FIN = "11", sampling frequency is about 8kHz. Additional
0]
:
0]
(RegAcCfg0[4:2])
SET_OSR[2:0]
FIN[1:0]
Table 16-20. Over-sampling ratio settings
(-)
(-)
000
001
010
011
100
101
110
111
00
01
10
11
16-14
Over-Sampling Ratio
Sampling Frequency f
1/32⋅f
1/4⋅f
1/8⋅f
∼8kHz
01/05
OSR (-)
1024
128
256
512
RC
RC
S
16
32
64
RC
8
(Table 16-19). Three sub-multiples of the internal
RC
(Eq. 13)
(Eq. 14)
= RC-based frequency)
1/16⋅f
1/64⋅f
1/8⋅f
∼4kHz
S
02
RCEXT
RCEXT
RCEXT
(Hz)
ELCONV
elementary incremental
XE8805/05A
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