8.4 Device Functional Modes

Table 8-1, Table 8-2, and Table 8-3 show the behavior of the driver, receiver, and INVALID(activelow) features

under all possible relevant combinations of inputs.

Table 8-1. Driver(1)

INPUTS

OUTPUT

DRIVER STATUS

DIN

FORCEON

FORCEOFF

VALID RIN RS-232

LEVEL

DOUT

X

X

L

X

Z

Powered off

L

H

H

X

H

Normal operation with

automatic power down disabled

H

H

H

X

L

L

L

H

Yes

H

Normal operation with

automatic power down enabled

H

L

H

Yes

L

L

L

H

No

Z

Powered off by

automatic power down feature

H

L

H

No

Z

(1)

H = high level, L = low level, X = irrelevant, Z = high impedance, Yes = |RIN| > 2.7 V, No = |RIN| <0.3 V

Table 8-2. Receiver(1)

INPUTS

OUTPUT

RECEIVER STATUS

RIN

EN

VALID RIN RS-232

LEVEL

ROUT

X

H

X

Z

Output off

L

L

X

H

Normal operation

H

L

X

L

Open

L

No

H

(1)

H = high level, L = low level, X = irrelevant, Z = high impedance (off), Open = input disconnected or connected driver off

Table 8-3. INVALID (1)

INPUTS

OUTPUT

RIN

FORCEON

FORCEOFF

EN

INVALID

L

X

X

X

H

H

X

X

X

H

Open

X

X

X

L

(1)

H = high level, L = low level, X = irrelevant, Z = high impedance (off), Open = input disconnected or connected driver off

DIN

DOUT

Auto-powerdown

INVALID

RIN

FORCEOFF

FORCEON

ROUT

EN

11

16

9

13

10

8

1

12

Figure 8-1. Logic Diagram

MAX3221

SLLS348P – JUNE 1999 – REVISED JULY 2021

www.ti.com

12

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