http://www.union-ic.com Rev.01 Mar.2015

10/22

UM3243

Function Tables

Table 1. Each Transmitter (Note 2)

INPUTS

OUTPUT

TRANSMITTER STATUS

TIN

FORCEON

FORCEOFF

______________________

VALID RIN

RS-232 LEVEL

TOUT

X

X

L

X

Z

Forced Power-Off

L

H

H

X

H

Normal Operation

with Forced Power-On

H

H

H

X

L

L

L

H

Yes

H

Normal Operation

with Auto Power-On

H

L

H

Yes

L

X

L

H

No

Z

Auto Power-Off

Note 2: H=high level, L=low level, X=irrelevant, Z=high impedance

Table 2. Each Receiver (Note 3)

INPUTS

OUTPUT

RECEIVER STATUS

RIN

FORCEON

FORCEOFF

______________________

ROUT

X

X

L

Z

Forced Power-Off

L

X

H

H

Normal Operation

H

X

H

L

Open

X

H

H

Table 3. ROUT2B and Outputs INVALID

________________

(Note 3)

INPUTS

OUTPUTS

OUTPUT STATUS

VALID RIN

RS-232 LEVEL

RIN2

FORCEON

FORCEOFF

______________________

INVALID

_________________

ROUT2B

Yes

L

X

X

H

L

Always Active

Yes

H

X

X

H

H

Yes

Open

X

X

H

L

No

Open

X

X

L

L

Note 3: H=high level, L=low level, X=irrelevant, Z=high impedance (off), Open=input disconnected

or connected driver off