AS1538/AS1540
Data Sheet - Detailed Description
Where:
SD: Single-Ended/Differential Inputs
0: Differential Inputs
1: Single-Ended Inputs
C2, C1, C0: Channel Selections
PD1, PD0: Power-Down Selection
X: Unused
Powerdown Selection
Powerdown modes for the AS1538/AS1540 are selected by setting bits PD0 and PD1 of a command byte (see Com-
mand Byte on page 12).
Table 5. Powerdown Mode Bit Settings
PD1
PD0
Description
0
0
1
1
0
1
0
1
Powerdown between A/D converter conversions.
Internal reference off and A/D converter on.
Internal reference on and A/D converter off.
Internal reference on and A/D converter on.
Channel Selection
Channel selection for the AS1538/AS1540 is made using a command byte (see Command Byte on page 12).
Table 6. Channel Selection Bit Settings1
SD
0
C2
0
C1
0
C0
0
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
+IN
–IN
-
+IN
-
-
–IN
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0
0
0
1
-
-
-
-
0
0
1
0
+IN
–IN
0
0
1
1
-
-
-
-
-
-
+IN
–IN
-
0
0
0
1
1
1
0
0
1
0
1
0
–IN
+IN
-
–IN
-
-
+IN
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
–IN
+IN
0
1
1
1
-
-
-
-
-
-
–IN
+IN
-
1
1
1
0
0
0
0
0
1
0
1
0
+IN
-
-
-
-
+IN
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
–IN
–IN
–IN
-
-
+IN
1
0
1
1
-
-
-
-
-
-
+IN
-
–IN
1
1
1
1
1
1
0
0
1
0
1
0
-
-
-
+IN
-
-
-
-
+IN
-
-
-
-
-
-
-
-
-
-
-
-
–IN
–IN
–IN
-
-
+IN
1
1
1
1
-
-
-
-
-
-
-
+IN
–IN
1. For the 4-channel AS1540 only combinations of CH0:CH3 applies.
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