LTC1863/LTC1867
APPLICATIO S I FOR ATIO
Analog Input Multiplexer
The analog input multiplexer is controlled by a 7-bit input
data word. The input data word is defined as follows:
SD OS S1 S0 COM UNI SLP
SD = SINGLE/DIFFERENTIAL BIT
OS = ODD/SIGN BIT
S1 = ADDRESS SELECT BIT 1
S0 = ADDRESS SELECT BIT 0
COM = CH7/COM CONFIGURATION BIT
UNI = UNIPOLAR/BIPOLAR BIT
SLP = SLEEP MODE BIT
Examples of Multiplexer Options
4 Differential
8 Single-Ended
+
(
–
)
–
(
+
)
{
+
(
–
)
–
(
+
)
{
+
(
–
)
–
(
+
)
{
+
(
–
)
–
(
+
)
{
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7/COM
+
+
+
+
+
+
+
+
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7/COM
GND (
–
)
7 Single-Ended
to CH7/COM
Combinations of Differential
and Single-Ended
+
+
+
+
+
+
+
CH0
CH1
CH2
CH3
CH4
CH5
CH6
+
–
{
–
+
{
+
+
+
+
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7/COM
GND (
–
)
18637 AI01
CH7/COM (
–
)
U
U
Changing the MUX Assignment “On the Fly”
1st Conversion
2nd Conversion
W
W
U U
U U
+
–
{
+
–
{
CH2
CH3
CH4
CH5
CH7/COM
(UNUSED)
–
+
+
+
{
{
CH2
CH3
CH4
CH5
CH7/COM (
–
)
18637 AI02
Tables 1 and 2 show the configurations when COM = 0,
and COM = 1.
Table 1. Channel Configuration (When COM = 0, CH7/COM Pin
Is Used as CH7)
SD
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
OS
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
S1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
S0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
COM
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Channel Configuration
“+”
“-”
CH0
CH2
CH4
CH6
CH1
CH3
CH5
CH7
CH0
CH2
CH4
CH6
CH1
CH3
CH5
CH7
CH1
CH3
CH5
CH7
CH0
CH2
CH4
CH6
GND
GND
GND
GND
GND
GND
GND
GND
Table 2. Channel Configuration (When COM = 1, CH7/COM Pin
Is Used as COMMON)
SD
1
1
1
1
1
1
1
OS
0
0
0
0
1
1
1
S1
0
0
1
1
0
0
1
S0
0
1
0
1
0
1
0
COM
1
1
1
1
1
1
1
Channel Configuration
"+"
"-"
CH0
CH2
CH4
CH6
CH1
CH3
CH5
CH7/COM
CH7/COM
CH7/COM
CH7/COM
CH7/COM
CH7/COM
CH7/COM
18637f
9
LINER [ LINEAR TECHNOLOGY ]
