sx8723 Semtech Corporation, sx8723 Datasheet - Page 26
sx8723
Manufacturer Part Number
sx8723
Description
Sx8723 Zoomingadc? For Pressure And Temperature Sensing
Manufacturer
Semtech Corporation
Datasheet
1.SX8723.pdf
(53 pages)
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ADVANCED COMMUNICATIONS & SENSING
Output Code Format
The ADC output code is a 16-bit word in two's complement format (see Table 15). For input voltages outside the
range, the output code is saturated to the closest full-scale value (i.e. 0x7FFF or 0x8000). For resolutions
smaller than 16 bits, the non-significant bits are forced to the values shown in Table 16. The output code,
expressed in LSBs, corresponds to:
Recalling equation 9, this can be rewritten as:
where, from Equation 10and Equation 11, the total PGA gain and offset are respectively:
and:
V1.5 © 2007 Semtech Corp.
ADC Input Voltage V
Table 16 - Last Forced LSBs in Conversion Output Registers for Resolution Settings Smaller than 16
SET_OSR[2:0]
+2.46146V
+2.46138V
-2.46146V
-2.46154V
Table 15 - Basic ADC Relationships (example for: V
+75µV
-75µV
000
001
010
011
100
101
110
111
0V
...
...
OUT
IN,ADC
ADC
bits (n < 16) (RegACOutMsb[7:0] & RegACOutLsb[7:0])
2
16
SET_NELC = 00
% of Full Scale (FS)
OUT
V
GDoff
REF
V
1000000000
IN
GD
,
ADC
ADC
+0.5 FS
-0.5 FS
10000000
TOT
ZoomingADC™ for Pressure and Temperature Sensing
100000
...
...
...
...
...
...
TOT
0
1000
2
GD
10
16
GDoff
-
-
-
GD
TOT
V
Equation 17
Equation 18
V
REF
3
SET_NELC = 01
IN
3
,
GD
26
ADC
,
GDoff
ADC
GD
2
100000000
GD
OSR
3
1000000
TOT
OSR
Output in LSBs
GDoff
10000
1
+215-1=+32'767
+215-2=+32'766
-215-1=-32'767
-215=-32'768
100
REF,ADC
V
1
1
-
-
-
REF
V
+1
...
-1
...
0
(V/V)
2
IN
,
ADC
= 5V, OSR = 64, n = 16 bits)
SET_NELC = 10
(LSB)
(V/V)
OSR
OSR
10000000
100000
1
1000
10
Output Code in Hex
-
-
-
-
(LSB)
www.semtech.com
SET_NELC = 11
7FFE
7FFF
8FFF
0001
0000
8001
8000
...
...
SX8723
1000000
10000
100
1
-
-
-
-