
16
LTC1544
Figure 23. Controller-Selectable DCE Port with DB-25 Connector
D2
D1
LTC1544
CTS
DSR
DTR
DCD
RTS
D3
R2
R1
R4
R3
D2
LTC1543
LL
RXD
RXC
TXC
SCTE
TXD
M0
M1
M2
DCE/DTE
VCC
VDD
VCC
VEE
GND
3
16
17
9
15
12
24
11
2
1
5
13
6
8
22
10
20
23
4
19
18
7
14
1544 F23
D3
R2
R1
R3
D1
C2
1
F
C1
1
F
C5
1
F
C3
1
F
C4
3.3
F
RXD A (104)
RXD B
RXC A (115)
RXC B
SCTE A (113)
SCTE B
TXD A (103)
TXD B
CTS A (106)
CTS B
DSR A (107)
DSR B
RTS A (105)
RTS B
LL A (141)
SGND (102)
SHIELD (101)
DB-25 FEMALE
CONNECTOR
TXC A (114)
TXC B
DCD A (109)
DCD B
DTR A (108)
DTR B
D4
16
10
9
7
6
4
3
8
11
12
13
5
2
15 18 17 19 20 22
LTC1344A
C6
100pF
C7
100pF
C8
100pF
VCC
5V
23 24
14
1
DCE/DTE
M2
M1
M0
CHARGE
PUMP
+
28
3
1
2
4
5
6
7
8
9
10
NC
11
12
13
14
1
2
3
4
5
6
7
8
10
9
INVERT
15
16
17
18
19
20
21
22
23
24
25
NC
27
26
25
24
23
22
21
20
19
18
17
16
15
26
27
28
VEE
M0
M1
M2
DCE/DTE
M2
M1
M0
11
12
13
14
21
LATCH
C12
1
F
C13
1
F
C11
1
F
C10
1
F
C9
1
F
TYPICAL APPLICATIO S
U