ICL3221E INTERSIL [Intersil Corporation], ICL3221E Datasheet - Page 12

• Manufacturer Part Number: ICL3221E
• Manufacturer: INTERSIL [Intersil Corporation]

Software Controlled (Manual) Powerdown
Most devices in the ICL32xxE family provide pins that allow
the user to force the IC into the low power, standby state.
On the ICL3222E and ICL3241E, the powerdown control is
via a simple shutdown (SHDN) pin. Driving this pin high
enables normal operation, while driving it low forces the IC
into its powerdown state. Connect SHDN to V
powerdown function isn’t needed. Note that all the receiver
outputs remain enabled during shutdown (see Table 2). For
the lowest power consumption during powerdown, the
receivers should also be disabled by driving the EN input
high (see next section, and Figures 2 and 3).
NOTE:
ICL3222E, ICL3241E
ICL3221E, ICL3223E
ICL3243E
4. Applies only to the ICL3241E and ICL3243E.
RECEIVER
PRESENT
SIGNAL
INPUT?
RS-232
N/A
N/A
N/A
N/A
Yes
Yes
Yes
Yes
Yes
Yes
AT
No
No
No
No
No
No
No
No
No
FORCEOFF
OR SHDN
INPUT
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
ICL3221E, ICL3222E, ICL3223E, ICL3232E, ICL3241E, ICL3243E
FORCEON
INPUT
12
N/A
N/A
N/A
N/A
H
H
X
X
X
X
H
X
X
L
L
L
L
L
L
TABLE 2. POWERDOWN AND ENABLE LOGIC TRUTH TABLE
INPUT
N/A
N/A
N/A
N/A
N/A
EN
H
H
H
H
H
H
H
L
L
L
L
L
L
L
CC
TRANSMITTER
OUTPUTS
if the
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
High-Z
Active
Active
Active
Active
Active
Active
Active
Active
RECEIVER
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
Active
Active
Active
Active
The ICL3221E, ICL3223E, and ICL3243E utilize a two pin
approach where the FORCEON and FORCEOFF inputs
determine the IC’s mode. For always enabled operation,
FORCEON and FORCEOFF are both strapped high. To
switch between active and powerdown modes, under logic
or software control, only the FORCEOFF input need be
driven. The FORCEON state isn’t critical, as FORCEOFF
dominates over FORCEON. Nevertheless, if strictly manual
control over powerdown is desired, the user must strap
FORCEON high to disable the automatic powerdown
circuitry. ICL3243E inverting (standard) receiver outputs also
disable when the device is in manual powerdown, thereby
eliminating the possible current path through a shutdown
peripheral’s input protection diode (see Figures 2 and 3).
OUTPUTS
(NOTE 4)
R
Active
Active
Active
Active
Active
Active
Active
Active
Active
OUTB
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
OUTPUT
INVALID
N/A
N/A
N/A
N/A
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
Manual Powerdown
Manual Powerdown with Receiver
Disabled
Normal Operation
Normal Operation withReceiver
Disabled
Normal Operation
(Auto Powerdown Disabled)
Normal Operation
(Auto Powerdown Enabled)
Powerdown Due to Auto Powerdown
Logic
Manual Powerdown
Manual Powerdown with Receiver
Disabled
Manual Powerdown
Manual Powerdown with Receiver
Disabled
Normal Operation
(Auto Powerdown Disabled)
Normal Operation
(Auto Powerdown Enabled)
Powerdown Due to Auto Powerdown
Logic
Manual Powerdown
Manual Powerdown
MODE OF OPERATION
June 22, 2007
FN4910.19