ICL3243ECVZ-T Datasheet, PDF (15/33 Pages) Intersil Corporation – ±15kV ESD Protected, +3V to +5.5V, 1μA, 250kbps, RS-232 Transmitters/Receivers

ICL3221E, ICL3222E, ICL3223E, ICL3232E, ICL3241E, ICL3243E
ICL3241E and ICL3243E monitor receivers remain
active even during manual power-down and forced
receiver disable, making them extremely useful for
Ring Indicator monitoring. Standard receivers driving
powered down peripherals must be disabled to
prevent current flow through the peripheral’s
protection diodes (see Figures 2 and 3). This renders
them useless for wake up functions, but the
corresponding monitor receiver can be dedicated to
this task as shown in Figure 3.
V_CC
R_XIN
-25V ≤ V_RIN ≤ +25V
GND
5kΩ
R_XOUT
GND ≤ V_ROUT ≤ V_CC
FIGURE 1. INVERTING RECEIVER CONNECTIONS
Power-Down Functionality
(Except ICL3232E)
The already low current requirement drops
significantly when the device enters power-down
mode. In power-down, supply current drops to 1µA,
because the on-chip charge pump turns off (V+
collapses to V_CC, V- collapses to GND), and the
transmitter outputs three-state. Inverting receiver
outputs may or may not disable in power-down; refer
to Table 2 for details. This micro-power mode makes
these devices ideal for battery powered and portable
applications.
Software Controlled (Manual) Power-Down
Most devices in the ICL32xxE family provide pins that
allow the user to force the IC into the low power,
standby state.
Low Power Operation
These 3V devices require a nominal supply current of
0.3mA, even at V_CC = 5.5V, during normal operation
(not in power-down mode). This is considerably less
than the 5mA to 11mA current required by comparable
5V RS-232 devices, allowing users to reduce system
power simply by switching to this new family.
Pin Compatible Replacements for 5V
Devices
On the ICL3222E and ICL3241E, the power-down
control is via a simple shutdown (SHDN) pin. Driving
this pin high enables normal operation, while driving it
low forces the IC into its power-down state. Connect
SHDN to V_CC if the power-down function isn’t needed.
Note that all the receiver outputs remain enabled
during shutdown (see Table 2). For the lowest power
consumption during power-down, the receivers should
also be disabled by driving the EN input high (see next
section, and Figures 2 and 3).
The ICL3221E, ICL3222E, ICL3232E are pin compatible
with existing 5V RS-232 transceivers - See the
“Features” section on page 1 for details.
The ICL3221E, ICL3223E, and ICL3243E utilize a two
pin approach where the FORCEON and FORCEOFF
inputs determine the IC’s mode. For always enabled
This pin compatibility coupled with the low I_CC and
wide operating supply range, make the ICL32xxE
potential lower power, higher performance drop-in
replacements for existing 5V applications. As long as
the ±5V RS-232 output swings are acceptable, and
transmitter input pull-up resistors aren’t required, the
IICL32xxE should work in most 5V applications.
operation, FORCEON and FORCEOFF are both strapped
high. To switch between active and power-down
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 power-
down is desired, the user must strap FORCEON high to
disable the automatic power-down circuitry. ICL3243E
When replacing a device in an existing 5V application,
inverting (standard) receiver outputs also disable when
it is acceptable to terminate C₃ to V_CC as shown on
the “Typical Operating Circuits” on page 2.
the device is in manual power-down, thereby
eliminating the possible current path through a
Nevertheless, terminate C₃ to GND if possible, as
slightly better performance results from this
shutdown peripheral’s input protection diode (see
Figures 2 and 3).
configuration.
TABLE 2. POWER-DOWN AND ENABLE LOGIC TRUTH TABLE
RS-232
SIGNAL
PRESENT
AT
RECEIVER
INPUT?
FORCEOFF
OR SHDN
INPUT
FORCEON
INPUT
EN
INPUT
TRANSMITTER
OUTPUTS
RECEIVER
OUTPUTS
R_OUTB
OUTPUTS
(NOTE 7)
INVALID
OUTPUT
MODE OF
OPERATION
ICL3222E, ICL3241E
N/A
L
N/A
L
High-Z
Active
Active
N/A Manual Power-Down
N/A
L
N/A
H
High-Z
High-Z
Active
N/A Manual Power-Down with
Receiver 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 with
Receiver Disabled
15
FN4910.21
February 22, 2010