LTC1543IG View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
LTC1543IG Datasheet PDF : 20 Pages
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LTC1543
APPLICATIONS INFORMATION
V.28 (RS232) Interface
A typical V.28 unbalanced interface is shown in Figure 17.
A V.28 single-ended generator output A with ground C is
connected to a single-ended receiver with input A' con-
nected to A, ground C' connected via the signal return
ground C.
In V.28 mode all switches are off except S3 inside the
LTC1543/LTC1544 which connects a 6k (R8) impedance
to ground in parallel with 20k (R5) plus 10k (R6) for a
combined impedance of 5k as shown in Figure 18. The
noninverting input is disconnected inside the LTC1543/
LTC1544 receiver and connected to a TTL level reference
voltage for a 1.4V receiver trip point.
V.35 Interface
A typical V.35 balanced interface is shown in Figure 19. A
V.35 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C', inputs A' connected to A, B' connected to B. The
V.35 interface requires a T or delta network termination at
the receiver end and the generator end. The receiver
differential impedance measured at the connector must be
100Ω␣ ±10Ω, and the impedance between shorted termi-
nals (A' and B') and ground C' must be 150Ω ±15Ω.
In V.35 mode, both switches S1 and S2 inside the LTC1344A
are on, connecting the T network impedance as shown in
Figure 20. The switch in the LTC1543 is off. The 30k input
GENERATOR
BALANCED
INTERCONNECTING
CABLE
LOAD
CABLE
TERMINATION
RECEIVER
A
A'
C
C'
1543 F17
Figure 17. Typical V.28 Interface
A'
A
R1 LTC1344A
51.5Ω
R5
R8
6k
20k
S1
S3
R3
S2 124Ω
R2
51.5Ω
B'
C'
R4
B
20k
GND
LTC1543
LTC1544
R6
10k
RECEIVER
R7
10k
1543 F18
Figure 18. V.28 Receiver Configuration
GENERATOR
BALANCED
INTERCONNECTING
CABLE
LOAD
CABLE
TERMINATION
RECEIVER
A
A'
50Ω
125Ω
50Ω
125Ω
50Ω
B
C
50Ω
B'
C'
1543 F19
Figure 19. Typical V.35 Interface
A'
A
R1 LTC1344A
51.5Ω
R5
R8
6k
20k
S1
R3
S3
S2 124Ω
R2
51.5Ω
B'
C'
R4
B
20k
GND
LTC1543
R6
10k
RECEIVER
R7
10k
1543 F20
Figure 20. V.35 Receiver Configuration
12
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