ltc1344aig-trpbf Linear Technology Corporation, ltc1344aig-trpbf Datasheet - Page 7

• Manufacturer Part Number: ltc1344aig-trpbf
• Description: Software Selectablecable Terminator
• Manufacturer: Linear Technology Corporation

APPLICATIONS
V.28 (RS232) Termination
A typical V.28 unbalanced interface is shown in Figure 8.
A V.28 single-ended generator output A with ground C is
connected to a single-ended receiver with inputs A
nected to A, ground C
ground to C. The V.28 standard requires a 5k terminating
resistor to ground which is included in almost all compli-
ant receivers as shown in Figure 9. Because the termina-
tion is included in the receiver, both switches S1 and S2 in
the LTC1344 are turned off.
Z
GENERATOR
Figure 7. V.11 Interface Using the LTC1344
A
B
C
– 3.25mA
ON
S1
Figure 6. Typical V.11 Interface
51.5
51.5
–10V
INTERCONNECTING
U
OFF
A
B
C
S2
BALANCED
CABLE
'
124
LTC1344
INFORMATION
connected via the signal return
U
–3V
A
B
C
'
'
'
I
Z
TERMINATION
W
CABLE
3V
Z
Z
100
MIN
LOAD
RECEIVER
V.11
RECEIVER
10V
3.25mA
V
1344 F06
U
1344 F07
Z
'
con-
V.35 Termination
A typical V.35 balanced interface is shown in Figure 10. A
V.35 differential generator with outputs A and B with
ground C is connected to a differential receiver with
ground C
V.35 interface requires a T-network termination at the
receiver end and the generator end. In V.35 mode both
switches S1 and S2 in the LTC1344 are turned on as
shown in Figure 11.
The differential impedance measured at the connector
must be 100
terminals A
input impedance of the V.35 receiver is connected in
parallel with the T-network inside the LTC1344, which can
cause the overall impedance to fail the specification on the
GENERATOR
A
B
C
'
Figure 9. V.28 Interface Using the LTC1344
, inputs A
'
OFF
and B
S1
Figure 8. Typical V.28 Interface
51.5
51.5
10 and the impedance between shorted
'
OFF
S2
'
to ground C
INTERCONNECTING
connected to A, B
A
C
BALANCED
124
CABLE
LTC1344
'
A
C
must be 150
'
'
TERMINATION
CABLE
'
1344 F09
5k
connected to B. The
RECEIVER
LOAD
V.28
LTC1344
RECEIVER
1344 F08
15 . The
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