
LTC2435/LTC2435-1
37
24351fc
Figure 41. Use a Differential Multiplexer to Expand Channel Capability
2435 F41
REF+
REF–
IN+
IN–
1, 7, 8, 9,
10, 15, 16
2
A0
A1
LTC2435/
LTC2435-1
VCC
GND
13
3
6
12
47μF
14
1
5
10
16
5V
15
11
2
TO OTHER
DEVICES
4
9
8
5V
+
74HC4052
3
4
5
6
applicaTions inForMaTion
Sample Driver for LTC2435/LTC2435-1 SPI Interface
Figure 41 shows the use of an LTC2435/LTC2435-1 with a
differential multiplexer. This is an inexpensive multiplexer
that will contribute some error due to leakage if used
directly with the output from the bridge, or if resistors
are inserted as a protection mechanism from overvolt-
age. Although the bridge output may be within the input
range of the A/D and multiplexer in normal operation,
some thought should be given to fault conditions that
could result in full excitation voltage at the inputs to the
multiplexer or ADC. The use of amplification prior to the
multiplexer will largely eliminate errors associated with
channel leakage developing error voltages in the source
impedance.
The LTC2435/LTC2435-1 have a very simple serial in-
terface that makes interfacing to microprocessors and
microcontrollers very easy.
Figure 42. Connecting the LTC2435/LTC2435-1 to a PIC16F73 MCU Using the SPI Serial Interface
LTC2435/
LTC2435-1
SCK
SDO
CS
13
12
11
13
14
15
17
18
RC2
RC3
RC4
RC6
RC7
PIC16F73
2435 F42
8
19
20
12
11
13
10
18
2
4
5
6
15
8
14
9
17
3
7
16
C1
C2
C3
C4
C5
VCC
1
2
3
4
5
6
7
8
9
X1
T1IN
T2IN
R1OUT
R2OUT
SHDN
C1+
C1–
C2+
C2–
T1OUT
T2OUT
R1IN
R2IN
VCC
V+
V–
GND
LT1180A