ICL3232E INTERSIL [Intersil Corporation], ICL3232E Datasheet - Page 16

• Manufacturer Part Number: ICL3232E
• Manufacturer: INTERSIL [Intersil Corporation]

NOTE:
ICL3221E, ICL3223E
ICL3243E
RECEIVER
7. Applies only to the ICL3241E and ICL3243E.
The INVALID output always indicates whether or not a
valid RS-232 signal is present at any of the receiver
inputs (see Table 2), giving the user an easy way to
determine when the interface block should power
down. In the case of a disconnected interface cable
where all the receiver inputs are floating (but pulled to
GND by the internal receiver pull down resistors), the
INVALID logic detects the invalid levels and drives the
output low. The power management logic then uses
this indicator to power down the interface block.
Reconnecting the cable restores valid levels at the
receiver inputs, INVALID switches high, and the power
management logic wakes up the interface block.
INVALID can also be used to indicate the DTR or RING
INDICATOR signal, as long as the other receiver inputs
are floating, or driven to GND (as in the case of a
powered down driver). Connecting FORCEOFF and
FORCEON together disables the automatic power-down
feature, enabling them to function as a manual
SHUTDOWN input (see Figure 4).
PRESENT
SIGNAL
RS-232
INPUT?
Yes
Yes
Yes
Yes
Yes
Yes
AT
No
No
No
No
No
No
No
No
No
ICL3221E, ICL3222E, ICL3223E, ICL3232E, ICL3241E, ICL3243E
FORCEOFF
OR SHDN
INPUT
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
TABLE 2. POWER-DOWN AND ENABLE LOGIC TRUTH TABLE (Continued)
FORCEON
INPUT
16
H
H
X
X
X
X
H
X
X
L
L
L
L
L
L
INPUT
N/A
N/A
N/A
N/A
N/A
EN
H
H
H
H
H
L
L
L
L
L
TRANSMITTER
OUTPUTS
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
Active
Active
Active
Active
Active
Active
RECEIVER
OUTPUTS
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
Active
Active
Active
Active
Active
Active
Active
Active
FIGURE 2. POWER DRAIN THROUGH POWERED
POWERED
DOWN
OUTPUTS
(NOTE 7)
UART
GND
R
Active
Active
Active
Active
Active
V
OUTB
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
CC
DOWN PERIPHERAL
Rx
Tx
V
INVALID
OUTPUT
CC
SHDN = GND
H
H
H
H
H
H
V
L
L
L
L
L
L
L
L
L
OUT
= V
(Auto Power-Down Disabled)
Normal Operation
(Auto Power-Down Enabled)
Power-Down Due to Auto
Power-Down Logic
with Receiver Disabled
with Receiver Disabled
(Auto Power-Down Disabled)
(Auto Power-Down Enabled)
Power-Down Due to Auto
Power-Down Logic
Manual Power-Down
Normal Operation
Manual Power-Down
Manual Power-Down
Manual Power-Down
Manual Power-Down
Normal Operation
Normal Operation
Manual Power-Down
CC
RS-232 CHIP
OPERATION
MODE OF
V
OLD
CURRENT
FLOW
CC
February 22, 2010
FN4910.21