+5V Multiprotocol, Pin-Selectable

Cable Terminator

_______________________________________________________________________________________

7

forcing them to the logic-high state if they are not

grounded. This allows interface-mode configuration by

simply strapping the appropriate pins to ground in the

interconnect cable.

V.11 Termination

A standard V.11 interface is shown in Figure 6. For high-

speed data transmission, the V.11 specification recom-

mends terminating the cable at the receiver with a 100

Ω

(min) resistor. The resistor, although not required, pre-

vents reflections from corrupting transmitted data.

Note: Z indicates high impedance, 1 = high, and 0 = low. Z, V.11, and V.35 refer to termination modes (Figure 4).

R2

52

Ω

R3

127

Ω

R1

52

Ω

S1

CLOSED

A

B

S2

OPEN

(a) V.11

(b) V.35

(c) Z

A

C

B

A

B

MAX13174E

R2

52

Ω

R3

127

Ω

R1

52

Ω

S1

CLOSED

S2

CLOSED

R2

52

Ω

R3

127

Ω

R1

52

Ω

S1

OPEN

S2

OPEN

CC

MAX13174E

MAX13174E

Figure 4. Termination Modes

Table 1. Termination Mode Select Table

PROTOCOL

DCE/

DTE

M2

M1

M0

R1

R2

R3

R4

R5

R6

V.10/RS-423

0

0

0

0

Z

Z

Z

Z

Z

Z

RS-530A

0

0

0

1

Z

Z

Z

V.11

V.11

V.11

RS-530

0

0

1

0

Z

Z

Z

V.11

V.11

V.11

X.21

0

0

1

1

Z

Z

Z

V.11

V.11

V.11

V.35

0

1

0

0

V.35

V.35

Z

V.35

V.35

V.35

RS-449/V.36

0

1

0

1

Z

Z

Z

V.11

V.11

V.11

V.28/RS-232

0

1

1

0

Z

Z

Z

Z

Z

Z

No Cable

0

1

1

1

V.11

V.11

V.11

V.11

V.11

V.11

V.10/RS-423

1

0

0

0

Z

Z

Z

Z

Z

Z

RS-530A

1

0

0

1

Z

Z

Z

Z

V.11

V.11

RS-530

1

0

1

0

Z

Z

Z

Z

V.11

V.11

X.21

1

0

1

1

Z

Z

Z

Z

V.11

V.11

V.35

1

1

0

0

V.35

V.35

V.35

Z

V.35

V.35

RS-449/V.36

1

1

0

1

Z

Z

Z

Z

V.11

V.11

V.28/RS-232

1

1

1

0

Z

Z

Z

Z

Z

Z

No Cable

1

1

1

1

V.11

V.11

V.11

V.11

V.11

V.11