ICL3232CV-T Datasheet, PDF (11/28 Pages) Intersil Corporation – One Microamp Supply-Current, +3V to +5.5V, 250kbps, RS-232 Transmitters/Receivers

ICL3221, ICL3222, ICL3223, ICL3232, ICL3241, ICL3243
Software Controlled (Manual) Powerdown
Most devices in the ICL32XX family provide pins that allow
the user to force the IC into the low power, standby state.
On the ICL3222 and ICL3241, 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_CC if the 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).
The ICL3221, ICL3223, and ICL3243 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. ICL3243 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).
TABLE 2. POWERDOWN AND ENABLE LOGIC TRUTH TABLE
RS-232
SIGNAL
PRESENT
AT
RECEIVER
INPUT?
FORCEOFF
(NOTE 4)
OR SHDN FORCEON EN TRANSMITTER RECEIVER R_OUTB
INPUT
INPUT INPUT OUTPUTS OUTPUTS OUTPUTS
INVALID
OUTPUT
MODE OF OPERATION
ICL3222, ICL3241
N.A.
L
N.A.
L
High-Z
Active
Active
N.A. Manual Powerdown
N.A.
L
N.A.
H
High-Z
High-Z
Active
N.A. Manual Powerdown w/Rcvr. Disabled
N.A.
H
N.A.
L
Active
Active
Active
N.A. Normal Operation
N.A.
H
N.A.
H
Active
High-Z
Active
N.A. Normal Operation w/Rcvr. Disabled
ICL3221, ICL3223
No
H
H
L
Active
Active
N.A.
L
Normal Operation
(Auto Powerdown Disabled)
No
H
H
H
Active
High-Z
N.A.
L
Yes
H
L
L
Active
Active
N.A.
H
Normal Operation
(Auto Powerdown Enabled)
Yes
H
L
H
Active
High-Z
N.A.
H
No
H
L
L
High-Z
Active
N.A.
L
Powerdown Due to Auto Powerdown
Logic
No
H
L
H
High-Z
High-Z
N.A.
L
Yes
L
X
L
High-Z
Active
N.A.
H
Manual Powerdown
Yes
L
X
H
High-Z
High-Z
N.A.
H
Manual Powerdown w/Rcvr. Disabled
No
L
X
L
High-Z
Active
N.A.
L
Manual Powerdown
No
L
X
H
High-Z
High-Z
N.A.
L
Manual Powerdown w/Rcvr. Disabled
ICL3243
No
H
H
N.A.
Active
Active
Active
L
Normal Operation
(Auto Powerdown Disabled)
Yes
H
L
N.A.
Active
Active
Active
H
Normal Operation
(Auto Powerdown Enabled)
No
H
L
N.A.
High-Z
Active
Active
L
Powerdown Due to Auto Powerdown
Logic
Yes
L
X
N.A.
High-Z
High-Z
Active
H
Manual Powerdown
No
L
X
N.A.
High-Z
High-Z
Active
L
Manual Powerdown
NOTE:
4. Applies only to the ICL3241 and ICL3243.
11
FN4805.21
March 1, 2006