MAX3238

3V TO 5.5V MULTICHANNEL RS232 LINE DRIVER/RECEIVER

WITH ±15kV ESD (HBM) PROTECTION

SLLS349J − JUNE 1999 − REVISED MARCH 2004

2

POST OFFICE BOX 655303

description/ordering information (continued)

Flexible control options for power management are featured when the serial port and driver inputs are inactive.

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

of operation, if the device does not sense valid signal transitions on all receiver and driver inputs for

approximately 30 s, the built-in charge pump and drivers are powered down, reducing the supply current to

1

µA. By disconnecting the serial port or placing the peripheral drivers off, auto-powerdown plus occurs if there

is no activity in the logic levels for the driver inputs. Auto-powerdown plus can be disabled when FORCEON

and FORCEOFF are high. With auto-powerdown plus enabled, the device activates automatically when a valid

signal is applied to any receiver or driver 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 all receiver input voltages are between −0.3 V and 0.3 V for more than 30

µs. Refer to Figure 5 for receiver

input levels.

Function Tables

EACH DRIVER

INPUTS

OUTPUT

DIN

FORCEON

FORCEOFF

TIME ELAPSED SINCE LAST

RIN OR DIN TRANSITION

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 plus disabled

L

L

H

<30 s

H

Normal operation with

H

L

H

<30 s

L

Normal operation with

auto-powerdown plus enabled

L

L

H

>30 s

Z

Powered off by

H

L

H

>30 s

Z

Powered off by

auto-powerdown plus feature

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

EACH RECEIVER

INPUTS

OUTPUTS

RIN1

RIN2−RIN3

FORCEOFF

TIME ELAPSED SINCE LAST RIN

OR DIN TRANSITION

ROUT1B

ROUT

RECEIVER STATUS

L

X

L

X

L

Z

Powered off while

H

XL

X

H

Z

Powered off while

ROUT1B is active

L

L

H

<30 s

L

H

L

H

H

<30 s

L

L

Normal operation with

H

L

H

<30 s

H

H

Normal operation with

auto-powerdown plus

disabled/enabled

H

H

H

<30 s

H

L

auto-powerdown plus

disabled/enabled

Open

Open

H

>30 s

L

H

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