MAX3238 Datasheet, PDF (2/15 Pages) Texas Instruments – 3-V TO 5.5-V MULTICHANNEL RS-232 LINE DRIVER/RECEIVER

MAX3238
ą
3ĆV TO 5.5ĆV MULTICHANNEL RSĆ232 LINE DRIVER/RECEIVER
WITH ±15ĆkV ESD (HBM) PROTECTION
SLLS349J − JUNE 1999 − REVISED MARCH 2004
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
DIN FORCEON FORCEOFF
TIME ELAPSED SINCE LAST
RIN OR DIN TRANSITION
X
X
L
X
L
H
H
X
H
H
H
X
L
L
H
<30 s
H
L
H
<30 s
L
L
H
>30 s
H
L
H
>30 s
H = high level, L = low level, X = irrelevant, Z = high impedance
OUTPUT
DOUT
DRIVER STATUS
Z
Powered off
H
Normal operation with
L
auto-powerdown plus disabled
H
Normal operation with
L
auto-powerdown plus enabled
Z
Powered off by
Z
auto-powerdown plus feature
EACH RECEIVER
INPUTS
OUTPUTS
RIN1
RIN2−RIN3
FORCEOFF
TIME ELAPSED SINCE LAST RIN
OR DIN TRANSITION
ROUT1B
ROUT
RECEIVER STATUS
L
X
L
H
X
L
X
L
Z
Powered off while
X
H
Z
ROUT1B is active
L
L
H
<30 s
L
H
L
H
H
H
L
H
H
H
H
<30 s
<30 s
<30 s
L
L
Normal operation with
H
H
auto-powerdown plus
H
L
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
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