Datasheet

28
LTC2404/LTC2408
APPLICATIONS INFORMATION
WUU
U
2404/08 F25
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
9
10
11
12
13
14
15
17
8-CHANNEL
MUX
GND
1, 5, 6, 16, 18, 22, 27, 28
23
20
25
19
21
24
CSADC
CSMUX
SCK
CLK
D
IN
SDO
26
F
O
LTC2408
ADCINMUXOUT
74
6
2
4
8
16
32
64
128
AV = 1, 2, 4...1283
V
IN
2
5V
10k
10k20k
10k20k
10k20k
10k20k
10k20k
10k20k
10k20k
3 2, 8
1µF
5V
V
REF
V
CC
V
CC
–
+
LTC1050
0.1V TO V
CC
24-BIT
∆Σ ADC
Figure 25. Using the Multiplexer to Produce Programmable Gains of 1 to 128
2404/08 F26
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
9
10
11
12
13
14
15
17
8-CHANNEL
MUX
ANALOG
INPUTS
GND
1, 5, 6, 16, 18, 22, 27, 28
23
20
25
19
21
24
CSADC
CSMUX
SCK
CLK
D
IN
SDO
26
F
O
LTC2408
ADCINMUXOUT
74
7
6
3
C1
0.022µF
2
4
R3
200k
C2
OPTIONAL GAIN
AND ROLL-OFF
OPTIONAL
BANDWIDTH
LIMIT
5V
R2
5.1K
3 2, 8
10µF
5V
V
REF
V
CC
V
CC
R4
5K
MAY BE REQUIRED BY OTHER
AMPLIFIERS (IS REQUIRED BY
BIPOLAR AMPLIFIERS)
R1
5.1k
–
+
LTC1050
24-BIT
∆Σ ADC
Figure 26. Inserting Gain Between the Multiplexer and the ADC Input