LTC2846 Linear Technology, LTC2846 Datasheet - Page 14

• Manufacturer Part Number: LTC2846
• Description: 3.3V Software-Selectable Multiprotocol Transceiver with Termination
• Manufacturer: Linear Technology

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LTC2846
APPLICATIO S I FOR ATIO
and LTC2845 receivers and connected to ground. The
cable termination is then the 30k input impedance to
ground of the LTC2844 and LTC2845 V.10 receiver.
V.11 (RS422) Interface
A typical V.11 balanced interface is shown in Figure 22. A
V.11 differential generator with outputs A and B and
ground C is connected to a differential receiver with input
A
connected via the signal return to ground C. The V.11
interface has a differential termination at the receiver end
that has a minimum value of 100 . The termination
resistor is optional in the V.11 specification, but for the
high speed clock and data lines, the termination is essen-
tial to prevent reflections from corrupting the data. The
receiver inputs must also be compliant with the imped-
ance curve shown in Figure 20.
In V.11 mode, all switches are off except S1 of the
LTC2846’s receivers which connects a 103 differential
1
networks on the LTC2846 can be treated identically if it is assumed that an S1 switch exists and is
always closed on the R2 and R3 receivers.
14
Actually, there is no switch S1 in receivers R2 and R3. However, for simplicity, all termination
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connected to A, input B
GENERATOR
C
A
B
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Figure 21. V.10 Receiver Configuration
A
B
C
Figure 22. Typical V.11 Interface
A
B
INTERCONNECTING
U
BALANCED
CABLE
GND
R8
6k
S3
20k
20k
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U
R5
R4
connected to B, and ground C
A
C
B
TERMINATION
R6
10k
R7
10k
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'
W
CABLE
RECEIVER
LTC2844
100
MIN
LOAD
2846 F21
RECEIVER
U
2846 F22
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termination impedance to the cable as shown in Figure
23
signals, so no termination other than their V.11 receivers’
30k input impedance is necessary.
V.28 (RS232) Interface
A typical V.28 unbalanced interface is shown in Figure 24.
A V.28 single-ended generator with output A and ground
C is connected to a single-ended receiver with input A
connected to A and ground C
return to ground C.
1
. The LTC2844 and LTC2845 only handle control
GENERATOR
C
A
B
B
C
A
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Figure 23. V.11 Receiver Configuration
Figure 25. V.28 Receiver Configuration
S1
R1
51.5
R2
51.5
S1
R1
51.5
R2
51.5
S2
Figure 24. Typical V.28 Interface
S2
C
A
INTERCONNECTING
124
124
R3
R3
BALANCED
CABLE
GND
GND
R8
6k
R8
6k
S3
S3
20k
20k
R5
R4
20k
20k
R5
R4
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connected via the signal
C
A
TERMINATION
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CABLE
R6
10k
R7
10k
R6
10k
R7
10k
RECEIVER
RECEIVER
LTC2846
LTC2846
LOAD
2846 F25
2846 F23
RECEIVER
sn2846 2846fs
2846 F24
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