Datasheet

7
LTC1387
BLOCK DIAGRAM
W
RS232 MODE
WITHOUT LOOPBACK
ON
13
R
A
C2C1
R
B
D
Y
D
Z
B
A
V
DD
V
CC
19
201
4
2
3
6
7
8
18
16
15
14
Y
Z
5
17
GND
DXEN
485/232
10
9
LTC1387 • BD
RXEN
12
11
V
EE
RS232 MODE
WITH LOOPBACK
ON
13
R
A
C2C1
R
B
D
Y
D
Z
V
DD
V
CC
19
201
2
3
6
7
8
18
16
15
14
Y
Z
17
GND
DXEN*
485/232
10
9
RXEN*
12
11
V
EE
RS485 MODE
WITHOUT LOOPBACK
ON
13
R
A
C2C1
R
B
D
Y
SLEW
B
A
V
DD
V
CC
19
201
4
2
3
6
7
8
18
16
15
14
Y
Z
5
17
GND
DXEN
485/232*
10
9
RXEN
12
11
V
EE
RS485 MODE
WITH LOOPBACK
ON
13
R
A
C2C1
R
B
D
Y
SLEW
V
DD
V
CC
19
201
2
3
6
7
8
18
16
15
14
Y
Z
17
GND
DXEN*
485/232*
10
9
RXEN*
12
11
V
EE
*485/232, DXEN, RXEN = V
CC
TEST CIRCUITS
Figure 2. RS485 Driver/Receiver
Timing Test Circuit
Figure 1. RS485 Driver
Test Load
R
R
V
OD
Z
Y
LTC1387 • F01
V
OC
R
L
C
L
LTC1387 • F02
Z
Y
C
L
B
R
A
15pF
D
SLEW
485 = 3V, DXEN = 3V, RXEN = 3V
Figure 3. RS485 Driver Output
Enable/Disable Timing Test Load
DR OUT
C
L
500Ω
S2
LTC1387 • F03
V
CC
S1
Figure 4. RS232 Driver
Timing Test Circuit
Figure 6. Receiver Output
Enable/Disable Timing Test Load
RECEIVER
OUT
C
L
1k
S2
LTC1387 • F06
V
CC
S1
Figure 5. RS232 Receiver
Timing Test Circuit
LTC1387 • F05
15pF
Y, Z
D
R
A, B
232 = 0V, DXEN = 3V, RXEN = 3V
R
L
LTC1387 • F04
Y, Z
D
C
L
232 = 0V, DXEN = 3V
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