ICL3245 Intersil Corporation, ICL3245 Datasheet - Page 8

• Manufacturer Part Number: ICL3245
• Description: 1ma, +3v To +5.5v, 1mbps, Rs-232 Transceivers With Enhanced Automatic Powerdown
• Manufacturer: Intersil Corporation

Powerdown Functionality
This 3V family of RS-232 interface devices requires a
nominal supply current of 0.3mA during normal operation
(not in powerdown mode). This is considerably less than the
5mA to 11mA current required of 5V RS-232 devices. The
already low current requirement drops significantly when the
device enters powerdown mode. In powerdown, supply
current drops to 1µA, because the on-chip charge pump
turns off (V+ collapses to V
the transmitter outputs three-state. Inverting receiver outputs
may or may not disable in powerdown; refer to Table 2 for
details. This micro-power mode makes these devices ideal
for battery powered and portable applications.
Software Controlled (Manual) Powerdown
These three devices allow the user to force the IC into the
low power, standby state, and utilize a two pin approach
NOTES:
ICL3225
ICL322X - INVALID DRIVING FORCEON AND FORCEOFF (EMULATES AUTOMATIC POWERDOWN)
ICL3245
ICL3245 - INVALID DRIVING FORCEON AND FORCEOFF (EMULATES AUTOMATIC POWERDOWN)
4. Applies only to the ICL3245.
5. Input is connected to INVALID Output.
RCVR OR
WITHIN
XMTR
EDGE
30s?
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
X
X
X
X
X
X
X
X
FORCEOFF
NOTE 5
NOTE 5
NOTE 5
NOTE 5
INPUT
H
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
FORCEON
CC
NOTE 5
NOTE 5
NOTE 5
NOTE 5
INPUT
8
, V- collapses to GND), and
H
H
X
X
H
H
X
X
L
L
L
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
High-Z
TABLE 2. POWERDOWN LOGIC TRUTH TABLE
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
ICL3225, ICL3245
RECEIVER
OUTPUTS
High-Z
High-Z
High-Z
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
Active
OUTPUTS
(NOTE 4)
R
Active
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.
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 enhanced automatic powerdown circuitry.
ICL3245 inverting (standard) receiver outputs also disable
when the device is in powerdown, thereby eliminating the
possible current path through a shutdown peripheral’s input
protection diode (see Figures 2 and 3).
Connecting FORCEOFF and FORCEON together disables
the enhanced automatic powerdown feature, enabling them
to function as a manual SHUTDOWN input (see Figure 4).
RECEIVER
PRESENT
INPUT?
RS-232
LEVEL
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
AT
No
No
No
No
No
No
No
No
No
No
OUTPUT
INVALID
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
L
Normal Operation (Enhanced
Auto Powerdown Disabled)
Normal Operation (Enhanced
Auto Powerdown Enabled)
Powerdown Due to Enhanced
Auto Powerdown Logic
Manual Powerdown
Normal Operation
Forced Auto Powerdown
Normal Operation (Enhanced
Auto Powerdown Disabled)
Normal Operation (Enhanced
Auto Powerdown Enabled)
Powerdown Due to Enhanced
Auto Powerdown Logic
Manual Powerdown
Normal Operation
Forced Auto Powerdown
MODE OF OPERATION
February 27, 2006
FN4878.8