ICL3232ECBN Intersil, ICL3232ECBN Datasheet - Page 17

• Manufacturer Part Number: ICL3232ECBN
• Description: IC TXRX RS-232 3-5.5V ESD 16SOIC
• Manufacturer: Intersil
• Type: Transceiverr

Specifications of ICL3232ECBN

• Number Of Drivers/receivers: 2/2
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

With any of the control schemes, the time required to
exit power-down, and resume transmission is only
100µs. A mouse, or other application, may need more
time to wake up from shutdown. If automatic
power-down is being utilized, the RS-232 device will
reenter power-down if valid receiver levels aren’t
reestablished within 30µs of the ICL32xxE powering up.
Figure 5 illustrates a circuit that keeps the ICL32xxE from
initiating automatic power-down for 100ms after
powering up. This gives the slow-to-wake peripheral
circuit time to reestablish valid RS-232 output levels.
FIGURE 3. DISABLED RECEIVERS PREVENT POWER
FIGURE 4. CONNECTIONS FOR MANUAL
POWERED
DOWN
UART
CPU
V
WAKE-UP
ICL3221E, ICL3222E, ICL3223E, ICL3232E, ICL3241E, ICL3243E
CC
LOGIC
LOGIC
PWR
MGT
TO
R
T
DRAIN
POWER-DOWN WHEN NO VALID
RECEIVER SIGNALS ARE PRESENT
X
X
FORCEOFF = GND
OR SHDN = GND, EN = V
TRANSITION
DETECTOR
V
UART
OUT
I/O
R2
R2
= HI-Z
V
OUTB
FORCEOFF
FORCEON
INVALID
17
T1
CC
OUT
IN
CC
ICL324XE
ICL3221E,
ICL3223E,
ICL3243E
R2
T1
OUT
IN
Automatic Power-Down
(ICL3221E, ICL3223E, ICL3243E Only)
Even greater power savings is available by using the
devices which feature an automatic power-down
function. When no valid RS-232 voltages (see Figure 6)
are sensed on any receiver input for 30µs, the charge
pump and transmitters power-down, thereby reducing
supply current to 1µA. Invalid receiver levels occur
whenever the driving peripheral’s outputs are shut off
(powered down) or when the RS-232 interface cable is
disconnected. The ICL32xxE powers back up whenever it
detects a valid RS-232 voltage level on any receiver
input. This automatic power-down feature provides
additional system power savings without changes to the
existing operating system.
Automatic power-down operates when the FORCEON
input is low, and the FORCEOFF input is high. Tying
FORCEON high disables automatic power-down, but
manual power-down is always available via the
overriding FORCEOFF input. Table 2 summarizes the
automatic power-down functionality.
FIGURE 5. CIRCUIT TO PREVENT AUTO
FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER
-0.3V
-2.7V
2.7V
0.3V
MANAGEMENT
POWER
UNIT
INVALID LEVEL - POWER-DOWN OCCURS AFTER 30µs
VALID RS-232 LEVEL - ICL32xxE IS ACTIVE
VALID RS-232 LEVEL - ICL32xxE IS ACTIVE
INDETERMINATE - POWER-DOWN MAY OR
INDETERMINATE - POWER-DOWN MAY OR
POWER-DOWN FOR 100ms AFTER
FORCED POWER-UP
LEVELS
MASTER POWER-DOWN LINE
MAY NOT OCCUR
MAY NOT OCCUR
ICL3221E, ICL3223E, ICL3243E
FORCEOFF
0.1µF
FORCEON
1MΩ
February 22, 2010
FN4910.21