10
LTC1346A
1346afa
APPLICATIONS INFORMATION
WU
U
LTC485
7V TO – 7V
GND POTENTIAL DIFFERENCE
VCC1
5V
100
9
100
9
AA
B
GND
LTC1346A F09
LTC1346A
VCC2
5V
GND
TTL
IN
TTL
OUT
VEE
–5V
–+
Figure 9. RS422/RS485 Receiver Interface
LTC1346 F10
RECEIVER
OUTPUT
5V/DIV
A
B
–10V
–5V
0V
5V
RECEIVER
INPUT
5V/DIV
RECEIVER
OUTPUT
5V/DIV
15V
5V
0V
LTC1346 F11
10V
5V
0V
A
B
RECEIVER
INPUT
5V/DIV
Figure 10. – 7V Common Mode
Figure 11. 12V Common Mode
Multiprotocol Application
The LTC1346A can be used in multiprotocol applications
where V.35, RS232 and RS422 (used in RS530, RS449
among others) signals may appear at the same port. The
LTC1346A switched current source driver is not compatible
with RS232 or RS422. However, the outputs when disabled
can share lines with RS232 drivers with a Shutdown feature
such as the LT1030 and RS422 drivers with a disable
feature such as the LTC486/LTC487 (Figure 12a).
The LTC1346A driver will not be damaged or load the
shared lines when disabled. The LTC1346A receiver can
receive V.35, RS232 and RS422 signals as shown in Figure
12b. The LTC1346A receiver is directly compatible with
V.35 and RS422. For RS232 signal, the noninverting input
of the receiver should be grounded. Because the line
termination for each of the protocols is different, some
form of termination switching should be included, either
the connector (as shown in Figures 12a and 12b) or on the
PCB.