MAX3223

3V TO 5.5V MULTICHANNEL RS232 LINE DRIVER/RECEIVER

WITH ±15kV ESD PROTECTION

SLLS409K − JANUARY 2000 − REVISED MARCH 2004

2

POST OFFICE BOX 655303

description/ordering information (continued)

Flexible control options for power management are available when the serial port is inactive. The

auto-powerdown feature functions when FORCEON is low and FORCEOFF is high. During this mode of

operation, if the device does not sense a valid RS-232 signal, the driver outputs are disabled. If FORCEOFF

is set low and EN is high, both drivers and receivers are shut off, and the supply current is reduced to 1

µA.

Disconnecting the serial port or turning off the peripheral drivers causes auto-powerdown to occur.

Auto-powerdown can be disabled when FORCEON and FORCEOFF are high. With auto-powerdown enabled,

the device is activated automatically when a valid signal is applied to any receiver input. The INVALID output

is used to notify the user if an RS-232 signal is present at any receiver input. INVALID is high (valid data) if any

receiver input voltage is greater than 2.7 V or less than −2.7 V, or has been between −0.3 V and 0.3 V for less

than 30

µs. INVALID is low (invalid data) if the receiver input voltage is between −0.3 V and 0.3 V for more than

30

µs. Refer to Figure 4 for receiver input levels.

Function Tables

EACH DRIVER

INPUTS

OUTPUT

DIN

FORCEON

FORCEOFF

VALID RIN

RS-232 LEVEL

OUTPUT

DOUT

DRIVER STATUS

X

X

L

X

Z

Powered off

L

H

H

X

H

Normal operation with

H

HH

X

L

Normal operation with

auto-powerdown disabled

L

L

H

Yes

H

Normal operation with

H

LH

Yes

L

Normal operation with

auto-powerdown enabled

L

L

H

No

Z

Powered off by

H

L

H

No

Z

Powered off by

auto-powerdown feature

H = high level, L = low level, X = irrelevant, Z = high impedance

EACH RECEIVER

INPUTS

OUTPUT

RIN

EN

VALID RIN

RS-232 LEVEL

OUTPUT

ROUT

L

L

X

H

H

LX

L

X

HX

Z

Open

L

No

H

H = high level, L = low level, X = irrelevant,

Z = high

impedance

(off),

Open

=

input

disconnected or connected driver off