LTC1090 Linear Technology, LTC1090 Datasheet - Page 10

• Manufacturer Part Number: LTC1090
• Description: Single Chip 10-Bit Data Acquisition System
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
Data transfer is initiated by a falling chip select (CS) signal.
After the falling CS is recognized, an 8-bit input word
is shifted into the D
for the next conversion. Simultaneously, the result of the
previous conversion is output on the D
of the data exchange the requested conversion begins and
CS should be brought high. After t
complete and the results will be available on the next data
transfer cycle. As shown below, the result of a conversion
is delayed by one CS cycle from the input word requesting
it.
2. Input Data Word
The LTC1090 8-bit input data word is clocked into the D
input on the first eight rising SCLK edges after chip select
is recognized. Further inputs on the D
ignored until the next CS cycle. The eight bits of the input
word are defined as follows:
LTC1090
10
D
D
IN
OUT
Data Input (D
SGL/
DIFF
D
D
IN
OUT
Transfer
Word 1
Data
Word 0
ODD/
SIGN
IN
) Word:
MUX Address
SELECT
Conversion
1
t
IN
U
CONV
A/D
input which configures the LTC1090
SELECT
U
D
D
0
IN
OUT
Transfer
Word 2
Data
Word 1
Unipolar/
Bipolar
UNI
CONV
W
Conversion
MSB First/
OUT
LSB First
, the conversion is
MSBF
t
CONV
A/D
IN
line. At the end
pin are then
WL1
U
Word Length
D
D
IN
OUT
Word 3
LTC1090 • AI02
Word 2
LTC1090• AI03
WL0
IN
Multiplexer (MLIX) 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
mode (SGL/DIFF = O) 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 shows some examples of multiplexer
assignments.
Table 1. Multiplexer Channel Selection
SGL/
DIFF
SGL/ ODD/
DIFF SIGN
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
MUX ADDRESS
MUX ADDRESS
SIGN
ODD
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
SELECT
SELECT
1
0
0
1
1
0
0
1
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
0
1
0
1
0
1
0
1
0
+
+
–
0
SINGLE ENDED CHANNEL SELECTION
DIFFERENTIAL CHANNEL SELECTION
1
+
1
–
+
2
+
2
+
–
3
+
3
–
+
4
+
4
+
–
5
+
5
–
+
6
+
6
+
–
7 COM
+
1090fc
7
–
+
–
–
–
–
–
–
–
–