Datasheet

11
LTC1290
1290fe
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S
A
O
PP
L
IC
AT
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I FOR ATIO
MUX Address
The first four bits of the input word assign the MUX
configuration for the requested conversion. For a given
channel selection, the converter will measure the voltage
between the two channels indicated by the + and – signs
in the selected row of Table 1. Note that in differential
MUX ADDRESS
DIFFERENTIAL CHANNEL SELECTION
Table 1. Multiplexer Channel Selection
MUX ADDRESS
SGL/
DIFF
SELECT
1 0
ODD
SIGN
10 00 + –
10 01 + –
10 10 + –
10 11 + –
11 00 + –
11 01 + –
11 10 + –
11 11 + –
SGL/
DIFF
ODD
SIGN
SELECT
1 0
00 00+–
00 01 +–
00 10 +–
00 11 + –
01 00–+
01 01 –+
01 10 –+
01 11 – +
0
1
23
4
567
0 1 2 3 4 5 6 7 COM
SINGLE-ENDED CHANNEL SELECTION
mode (SGL/DIFF = 0) measurements are limited to four
adjacent input pairs with either polarity. In single-ended
mode, all input channels are measured with respect to
COM.
Figure 1. Examples of Multiplexer Options on the LTC1290
0
1
2
3
4
5
6
7
CHANNEL
COM (
–
)
8 Single-Ended
+
+
+
+
+
+
+
0,1
CHANNEL
4 Differential
2,3
4,5
6,7
+ (
–
)
+
+
(
–
)
+ (
–
)
+ (
–
)
–
(
+
)
–
(
+
)
–
(
+
)
–
(
+
)
4
5
6
7
CHANNEL
COM (
–
)
Combinations of Differential and Single-Ended
+
+
+
+
+
+
0,1
2,3
–
–
COM (UNUSED)
Changing the MUX Assignment “On the Fly”
COM (
–
)
4,5
6,7
5,4
1ST CONVERSION 2ND CONVERSION
+
–
+
–
+
–
+
+
7
6
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LTC1290 • F01