14

LTC2846

sn2846 2846fs

Figure 22. Typical V.11 Interface

Figure 21. V.10 Receiver Configuration

Figure 24. Typical V.28 Interface

Figure 25. V.28 Receiver Configuration

Figure 23. V.11 Receiver Configuration

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.

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

Ω. 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

Ω differential

termination impedance to the cable as shown in Figure

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.

R5

20k

LTC2844

RECEIVER

2846 F21

A

B

A

'

B

'

C

'

R8

6k

S3

R6

10k

R7

10k

GND

R4

20k

AA

'

B

C

B

'

C

'

GENERATOR

BALANCED

INTERCONNECTING

CABLE

LOAD

CABLE

TERMINATION

RECEIVER

100

Ω

MIN

2846 F22

R3

124

Ω

R5

20k

LTC2846

RECEIVER

2846 F23

A

'

B

'

C

'

R1

51.5

Ω

R8

6k

S2

S3

R2

51.5

Ω

R6

10k

R7

10k

GND

R4

20k

S1

AA

'

CC

'

GENERATOR

BALANCED

INTERCONNECTING

CABLE

LOAD

CABLE

TERMINATION

RECEIVER

2846 F24

R3

124

Ω

R5

20k

LTC2846

RECEIVER

2846 F25

A

'

B

'

C

'

R1

51.5

Ω

R8

6k

S2

S3

R2

51.5

Ω

R6

10k

R7

10k

GND

R4

20k

S1