SN65C3238, SN75C3238

3V TO 5.5V MULTICHANNEL RS232 COMPATIBLE LINE DRIVER/RECEIVER

SLLS352F − JUNE 1999 − REVISED OCTOBER 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 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 will occur 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 automatically activates once 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

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

RIN2

RIN1,

RIN3−RIN5

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