4-1
TM
File Number
4876
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143
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Intersil and Design is a trademark of Intersil Corporation.
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Copyright
Intersil Corporation 2000
ICL3244
1Microamp, +3V to +5.5V, 250kbps,
RS-232 Transceiver with Enhanced
Automatic Powerdown
The Intersil ICL32XX devices are 3.0V to 5.5V powered
RS-232 transmitters/receivers which meet ElA/TIA-232 and
V.28/V.24 specifications, even at V
CC
= 3.0V. Targeted
applications are PDAs, Palmtops, and notebook and laptop
computers where the low operational, and even lower
standby, power consumption is critical. Efficient on-chip
charge pumps, coupled with manual and enhanced
automatic powerdown functions, reduce the standby supply
current to a 1
A trickle. Small footprint packaging, and the
use of small, low value capacitors ensure board space
savings as well. Data rates greater than 250kbps are
guaranteed at worst case load conditions. This family is fully
compatible with 3.3V only systems, mixed 3.3V and 5.0V
systems, and 5.0V only systems.
The ICL3244 is a 3 driver, 5 receiver device that provides a
complete serial port suitable for laptop or notebook
computers. It also includes a noninverting always-active
receiver for "wake-up" capability.
This device, features an enhanced automatic powerdown
function which powers down the on-chip power-supply and
driver circuits. This occurs when all receiver and transmitter
inputs detect no signal transitions for a period of 30s. The
ICL3244 powers back up, automatically, whenever it senses
a transition on any transmitter or receiver input.
Table 1 summarizes the features of the device represented
by this data sheet, while Application Note AN9863
summarizes the features of each device comprising the
ICL3244 3V family.
Features
Manual and Enhanced Automatic Powerdown Features
Drop in Replacement for MAX3244
Meets EIA/TIA-232 and V.28/V.24 Specifications at 3V
Latch-Up Free
On-Chip Voltage Converters Require Only Four External
0.1
F Capacitors
Guaranteed Mouse Driveability
Receiver Hysteresis For Improved Noise Immunity
Guaranteed Minimum Data Rate . . . . . . . . . . . . 250kbps
Guaranteed Minimum Slew Rate . . . . . . . . . . . . . . . 6V/
s
Wide Power Supply Range. . . . . . . . Single +3V to +5.5V
Low Supply Current in Powerdown State . . . . . . . . . . 1
A
Applications
Any System Requiring RS-232 Communication Ports
- Battery Powered, Hand-Held, and Portable Equipment
- Laptop Computers, Notebooks, Palmtops
- Modems, Printers and other Peripherals
- Cellular/Mobile Phones
Related Literature
- Application Note AN9863, "3V to +5.5V, 250k-1Mbps,
RS-232 Transmitters/Receivers"
Pinout
ICL3244 (SOIC, SSOP)
TOP VIEW
Ordering Information
PART NO.
TEMP.
RANGE (
o
C)
PACKAGE
PKG. NO.
ICL3244CA
0 to 70
28 Ld SSOP
M28.209
ICL3244CB
0 to 70
28 Ld SOIC
M28.3
NOTE: Most surface mount devices are available on tape and reel;
add "-T" to suffix.
C2+
C2-
V-
R1
IN
R2
IN
R3
IN
R4
IN
R5
IN
T1
OUT
T3
OUT
T3
IN
T2
IN
T1
IN
C1+
V
CC
GND
C1-
FORCEON
INVALID
R1
OUT
R2
OUT
R3
OUT
R4
OUT
R5
OUT
V+
FORCEOFF
R2
OUTB
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
T2
OUT
TABLE 1. SUMMARY OF FEATURES
PART
NUMBER
NO. OF
Tx.
NO. OF
Rx.
NO. OF
MONITOR Rx.
(R
OUTB
)
DATA
RATE
(kbps)
Rx. ENABLE
FUNCTION?
READY
OUTPUT?
MANUAL
POWER-
DOWN?
ENHANCED
AUTOMATIC
POWERDOWN
FUNCTION?
ICL3244
3
5
1
250
No
No
Yes
Yes
Data Sheet
June 2000
4-2
Typical Operating Circuit
ICL3244
Pin Descriptions
PIN
FUNCTION
V
CC
System Power Supply Input (3.0V to 5.5V).
V+
Internally Generated Positive Transmitter Supply (+5.5V).
V-
Internally Generated Negative Transmitter Supply (-5.5V).
GND
Ground Connection.
C1+
External Capacitor (Voltage Doubler) is connected to this lead.
C1-
External Capacitor (Voltage Doubler) is connected to this lead.
C2+
External Capacitor (Voltage Inverter) is connected to this lead.
C2-
External Capacitor (Voltage Inverter) is connected to this lead.
T
IN
TTL/CMOS Compatible Transmitter Inputs.
T
OUT
RS-232 Level (Nominally
5.5V) Transmitter Outputs.
R
IN
RS-232 Compatible Receiver Inputs.
R
OUT
TTL/CMOS Level Receiver Outputs.
R
OUTB
TTL/CMOS Level, Noninverting, Always Enabled Receiver Outputs.
INVALID
Active Low Output that indicates if no valid RS-232 levels are present on any receiver input.
FORCEOFF Active Low to Shut Down Transmitters and On-Chip Power Supply. This overrides any automatic circuitry and FORCEON (see Table 2).
FORCEON
Active High Input to override automatic powerdown circuitry thereby keeping transmitters active. (FORCEOFF must be high).
26
V
CC
T1
OUT
T2
OUT
T3
OUT
T1
IN
T2
IN
T3
IN
T
1
T
2
T
3
0.1
F
+
0.1
F
+
0.1
F
14
13
9
10
12
11
28
24
27
3
V+
V-
C1+
C1-
C2+
C2-
+
0.1
F
1
2
R1
OUT
R1
IN
4
5k
R2
OUT
R2
IN
5
18
5k
R3
OUT
R3
IN
6
17
5k
R4
OUT
R4
IN
7
16
5k
R5
OUT
R5
IN
R
5
8
15
5k
19
R2
OUTB
C
1
C
2
+
C
3
C
4
FORCEON
FORCEOFF
23
GND
22
+3.3V
+
0.1
F
20
25
V
CC
TTL/CMOS
LOGIC LEVELS
RS-232
LEVELS
RS-232
LEVELS
R
1
R
2
R
3
R
4
21
INVALID
TO POWER
CONTROL LOGIC
ICL3244
ICL3244
4-3
Absolute Maximum Ratings
Thermal Information
V
CC
to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
V+ to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V
V- to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V
V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V
Input Voltages
T
IN
, FORCEOFF, FORCEON. . . . . . . . . . . . . . . . . . . -0.3V to 6V
R
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
25V
Output Voltages
T
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13.2V
R
OUT
, INVALID. . . . . . . . . . . . . . . . . . . . . . . . -0.3V to V
CC
+0.3V
Short Circuit Duration
T
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . 0
o
C to 70
o
C
Thermal Resistance (Typical, Note 1)
JA
(
o
C/W)
28 Ld SOIC Package . . . . . . . . . . . . . . . . . . . . . . . .
75
28 Ld SSOP Package . . . . . . . . . . . . . . . . . . . . . . .
100
Moisture Sensitivity (see Technical Brief TB363)
All Packages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Level 1
Maximum Junction Temperature (Plastic Package) . . . . . . . 150
o
C
Maximum Storage Temperature Range . . . . . . . . . . -65
o
C to 150
o
C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300
o
C
(SOIC, SSOP- Lead Tips Only)
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE:
1.
JA
is measured with the component mounted on an evaluation PC board in free air.
Electrical Specifications
Test Conditions: V
CC
= 3V to 5.5V, C
1
- C
4
= 0.1
F; Unless Otherwise Specified.
Typicals are at T
A
= 25
o
C
PARAMETER
TEST CONDITIONS
TEMP
(
o
C)
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS
Supply Current, Automatic
Powerdown
All R
IN
Open, FORCEON = GND, FORCEOFF = V
CC
25
-
1.0
10
A
Supply Current, Powerdown
FORCEOFF = GND
25
-
1.0
10
A
Supply Current,
Automatic Powerdown Disabled
All Outputs Unloaded, FORCEON = FORCEOFF = V
CC
25
-
0.3
1.0
mA
LOGIC AND TRANSMITTER INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
T
IN
, FORCEON, FORCEOFF
Full
-
-
0.8
V
Input Logic Threshold High
T
IN
, FORCEON, FORCEOFF
V
CC
= 3.3V
Full
2.0
-
-
V
V
CC
= 5.0V
Full
2.4
-
-
V
Input Leakage Current
T
IN
, FORCEON, FORCEOFF
Full
-
0.01
1.0
A
Output Leakage Current
FORCEOFF = GND
Full
-
0.05
10
A
Output Voltage Low
I
OUT
= 1.6mA
Full
-
-
0.4
V
Output Voltage High
I
OUT
= -1.0mA
Full
V
CC
-0.6 V
CC
-0.1
-
V
RECEIVER INPUTS
Input Voltage Range
Full
-25
-
25
V
Input Threshold Low
V
CC
= 3.3V
25
0.6
1.2
-
V
V
CC
= 5.0V
25
0.8
1.5
-
V
Input Threshold High
V
CC
= 3.3V
25
-
1.5
2.4
V
V
CC
= 5.0V
25
-
1.8
2.4
V
Input Hysteresis
25
-
0.5
-
V
Input Resistance
25
3
5
7
k
TRANSMITTER OUTPUTS
Output Voltage Swing
All Transmitter Outputs Loaded with 3k
to Ground
Full
5.0
5.4
-
V
ICL3244
4-4
Output Resistance
V
CC
= V+ = V- = 0V, Transmitter Output =
2V
Full
300
10M
-
Output Short-Circuit Current
Full
-
35
60
mA
Output Leakage Current
V
OUT
=
12V, V
CC
= 0V or 3V to 5.5V,
Automatic Powerdown or FORCEOFF = GND
Full
-
-
25
A
MOUSE DRIVEABILITY
Transmitter Output Voltage
(Figure 11)
T1
IN
= T2
IN
= GND, T3
IN
= V
CC
, T3
OUT
Loaded with 3k
to
GND, T1
OUT
and T2
OUT
Loaded with 2.5mA Each
Full
5
-
-
V
ENHANCED AUTOMATIC POWERDOWN (FORCEON = GND, FORCEOFF = V
CC
)
Receiver Input Thresholds to
INVALID High
ICL3244 Powers Up (Figure 6)
Full
-2.7
-
2.7
V
Receiver Input Thresholds to
INVALID Low
ICL3244 Powers Down (Figure 6)
Full
-0.3
-
0.3
V
INVALID Output Voltage Low
I
OUT
= 1.6mA
Full
-
-
0.4
V
INVALID Output Voltage High
I
OUT
= -1.0mA
Full
V
CC
-0.6
-
-
V
Receiver Positive or Negative
Threshold to INVALID High Delay
(t
INVH
)
25
-
1
-
s
Receiver Positive or Negative
Threshold to INVALID Low Delay
(t
INVL
)
25
-
30
-
s
Receiver or Transmitter Edge to
Transmitters Enabled Delay (t
WU
)
Note 2
25
-
100
-
s
Receiver or Transmitter Edge to
Transmitters Enabled Delay
(t
AUTOPWDN
)
Note 2
Full
15
30
60
s
TIMING CHARACTERISTICS
Maximum Data Rate
R
L
= 3k
,
C
L
= 1000pF, One Transmitter Switching
Full
250
500
-
kbps
Receiver Propagation Delay
Receiver Input to Receiver
Output, C
L
= 150pF
t
PHL
25
-
0.15
-
s
t
PLH
25
-
0.15
-
s
Receiver Output Enable Time
Normal Operation
25
-
200
-
ns
Receiver Output Disable Time
Normal Operation
25
-
200
-
ns
Transmitter Skew
t
PHL
- t
PLH
25
-
100
-
ns
Receiver Skew
t
PHL
- t
PLH
25
-
50
-
ns
Transition Region Slew Rate
V
CC
= 3.3V,
R
L
= 3k
to 7k
,
Measured From 3V to -3V or -3V
to 3V
C
L
= 150pF to 1000pF
25
6
-
30
V/
s
C
L
= 150pF to 2500pF
25
4
8
30
V/
s
ESD PERFORMANCE
RS-232 Pins (T
OUT
, R
IN
)
Human Body Model
25
-
>
8
-
kV
IEC1000-4-2 Contact Discharge
25
-
8
-
kV
IEC1000-4-2 Air Gap Discharge
25
-
8
-
kV
All Other Pins
Human Body Model
25
-
3
-
kV
NOTE:
2. An "edge" is defined as a transition through the transmitter or receiver input thresholds.
Electrical Specifications
Test Conditions: V
CC
= 3V to 5.5V, C
1
- C
4
= 0.1
F; Unless Otherwise Specified.
Typicals are at T
A
= 25
o
C (Continued)
PARAMETER
TEST CONDITIONS
TEMP
(
o
C)
MIN
TYP
MAX
UNITS
ICL3244
4-5
Detailed Description
ICL32XX interface ICs operate from a single +3V to +5.5V
supply, guarantee a 250kbps minimum data rate, require
only four small external 0.1
F capacitors, feature low power
consumption, and meet all ElA RS-232C and V.28
specifications. The circuit is divided into three sections: The
charge pump, the transmitters, and the receivers.
Charge-Pump
Intersil's new ICL32XX family utilizes regulated on-chip dual
charge pumps as voltage doublers, and voltage inverters to
generate
5.5V transmitter supplies from a V
CC
supply as
low as 3.0V. This allows these devices to maintain RS-232
compliant output levels over the
10% tolerance range of
3.3V powered systems. The efficient on-chip power supplies
require only four small, external 0.1
F capacitors for the
voltage doubler and inverter functions at V
CC
= 3.3V. See
the "Capacitor Selection" section, and Table 3 for capacitor
recommendations for other operating conditions. The charge
pumps operate discontinuously (i.e., they turn off as soon as
the V+ and V- supplies are pumped up to the nominal
values), resulting in significant power savings.
Transmitters
The transmitters are proprietary, low dropout, inverting
drivers that translate TTL/CMOS inputs to EIA/TIA-232
output levels. Coupled with the on-chip
5.5V supplies,
these transmitters deliver true RS-232 levels over a wide
range of single supply system voltages.
Transmitter outputs disable and assume a high impedance
state when the device enters the powerdown mode (see
Table 2). These outputs may be driven to
12V when
disabled.
All devices guarantee a 250kbps data rate for full load
conditions (3k
and 1000pF), V
CC
3.0V, with one
transmitter operating at full speed. Under more typical
conditions of V
CC
3.3V, R
L
= 3k
, and C
L
= 250pF, one
transmitter easily operates at 1Mbps.
Transmitter inputs float if left unconnected, and may cause
I
CC
increases. Connect unused inputs to GND for the best
performance.
Receivers
The ICL3244 contains both standard inverting, tri-stable
receivers, and a single noninverting (monitor) receiver
(denoted by the R
OUTB
label) that is always active,
regardless of the state of any control lines. Both receiver
types convert RS-232 signals to CMOS output levels and
accept inputs up to
25V while presenting the required 3k
to 7k
input impedance (see Figure 1) even if the power is
off (V
CC
= 0V). The receivers' Schmitt trigger input stage
uses hysteresis to increase noise immunity and decrease
errors due to slow input signal transitions.
The inverting receivers disable during forced (manual)
powerdown, but not during automatic powerdown (see Table
2). Conversely, the monitor receiver remains active even
TABLE 2. POWERDOWN LOGIC TRUTH TABLE
RCVR OR
XMTR
EDGE
WITHIN 30
SEC?
FORCEOFF
INPUT
FORCEON
INPUT
TRANSMITTER
OUTPUTS
RECEIVER
OUTPUTS
R
OUTB
OUTPUTS
RS-232
LEVEL
PRESENT
AT
RECEIVER
INPUT?
INVALID
OUTPUT
MODE OF OPERATION
ICL3244
NO
H
H
Active
Active
Active
No
L
Normal Operation (Enhanced
Auto Powerdown Disabled)
NO
H
H
Active
Active
Active
Yes
H
YES
H
L
Active
Active
Active
No
L
Normal Operation (Enhanced
Auto Powerdown Enabled)
YES
H
L
Active
Active
Active
Yes
H
NO
H
L
High-Z
Active
Active
No
L
Powerdown Due to Enhanced
Auto Powerdown Logic
NO
H
L
High-Z
Active
Active
Yes
H
X
L
X
High-Z
High-Z
Active
No
L
Manual Powerdown
X
L
X
High-Z
High-Z
Active
Yes
H
ICL3244 - INVALID DRIVING FORCEON AND FORCEOFF (EMULATES AUTOMATIC POWERDOWN)
X
Note 3
Note 3
Active
Active
Active
Yes
H
Normal Operation
X
Note 3
Note 3
High-Z
High-Z
Active
No
L
Forced Auto Powerdown
NOTE:
3. Input is connected to INVALID Output.
ICL3244
4-6
during manual powerdown making it 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.
Powerdown Functionality
This 3V RS-232 interface device 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 1
A, 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 powerdown; refer to Table 2 for
details. This micro-power mode makes this device ideal for
battery powered and portable applications.
Software Controlled (Manual) Powerdown
The ICL3244 allows the user to force the IC into the low
power, standby state, and utilizes 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 enhanced automatic powerdown circuitry.
ICL3244 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).
With any of the above control schemes, the time required to
exit powerdown, and resume transmission is only 100
s.
When using both manual and enhanced automatic
powerdown (FORCEON = 0), the ICL3244 won't power up
from manual powerdown until both FORCEOFF and
FORCEON are driven high, or until a transition occurs on a
receiver or transmitter input. Figure 5 illustrates a circuit for
R
XOUT
GND
V
ROUT
V
CC
5k
R
XIN
-25V
V
RIN
+25V
GND
V
CC
FIGURE 1. INVERTING RECEIVER CONNECTIONS
FIGURE 2. POWER DRAIN THROUGH POWERED DOWN
PERIPHERAL
OLD
V
CC
POWERED
GND
SHDN = GND
V
CC
Rx
Tx
V
CC
CURRENT
V
OUT
= V
CC
FLOW
RS-232 CHIP
DOWN
UART
FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN
ICL3244
TRANSITION
R
X
T
X
R2
OUTB
R2
OUT
T1
IN
FORCEOFF = GND
V
CC
V
CC
TO
R2
IN
T1
OUT
V
OUT
= HI-Z
POWERED
DETECTOR
DOWN
UART
WAKE-UP
LOGIC
FIGURE 4. CONNECTIONS FOR MANUAL POWERDOWN
WHEN NO VALID RECEIVER SIGNALS ARE
PRESENT
PWR
FORCEOFF
INVALID
CPU
I/O
FORCEON
ICL3244
MGT
LOGIC
UART
ICL3244
4-7
ensuring that the ICL3244 powers up as soon as
FORCEOFF switches high. The rising edge of the Master
Powerdown signal forces the device to power up, and the
ICL3244 returns to enhanced automatic powerdown mode
an RC time constant after this rising edge. The time constant
isn't critical, because the ICL3244 remains powered up for
30 seconds after the FORCEON falling edge, even if there
are no signal transitions. This gives slow-to-wake systems
(e.g., a mouse) plenty of time to start transmitting, and as
long as it starts transmitting within 30 seconds both systems
remain enabled.
INVALID Output
The INVALID output always indicates (see Table 2) whether
or not 30
s have elapsed with invalid RS-232 signals (see
Figures 6 and 8) persisting on all of the receiver inputs,
giving the user an easy way to determine when the interface
block should power down. Invalid receiver levels occur
whenever the driving peripheral's outputs are shut off
(powered down) or when the RS-232 interface cable is
disconnected. In the case of a disconnected interface cable
where all the receiver inputs are floating (but pulled to GND
by the internal receiver pull down resistors), the INVALID
logic detects the invalid levels and drives the output low. The
power management logic then uses this indicator to power
down the interface block. Reconnecting the cable restores
valid levels at the receiver inputs, INVALID switches high,
and the power management logic wakes up the interface
block. INVALID can also be used to indicate the DTR or
RING INDICATOR signal, as long as the other receiver
inputs are floating, or driven to GND (as in the case of a
powered down driver).
Enhanced Automatic Powerdown
Even greater power savings is available by using this device
which features an enhanced automatic powerdown function.
When the enhanced powerdown logic determines that no
transitions have occurred on any of the transmitter nor
receiver inputs for 30 seconds, the charge pump and
transmitters powerdown, thereby reducing supply current to
1
A. The ICL3244 automatically powers back up whenever it
detects a transition on one of these inputs. This automatic
powerdown feature provides additional system power
savings without changes to the existing operating system.
Enhanced automatic powerdown operates when the
FORCEON input is low, and the FORCEOFF input is high.
Tying FORCEON high disables automatic powerdown, but
manual powerdown is always available via the overriding
FORCEOFF input. Table 2 summarizes the enhanced
automatic powerdown functionality.
Figure 7 illustrates the enhanced powerdown control logic.
Note that once the ICL3244 enters powerdown (manually or
automatically), the 30 second timer remains timed out (set),
keeping the ICL3244 powered down until FORCEON
transitions high, or until a transition occurs on a receiver or
transmitter input.
The INVALID output signal switches low to indicate that
invalid levels have persisted on all of the receiver inputs for
more than 30
s (see Figure 8), but this has no direct effect
on the state of the ICL3244 (see the next sections for
methods of utilizing INVALID to power down the device).
INVALID switches high 1
s after detecting a valid RS-232
level on a receiver input. INVALID operates in all modes
(forced or automatic powerdown, or forced on), so it is also
useful for systems employing manual powerdown circuitry.
The time to recover from automatic powerdown mode is
typically 100
s.
FIGURE 5. CIRCUIT TO ENSURE IMMEDIATE POWER UP
WHEN EXITING FORCED POWERDOWN
FORCEOFF
FORCEON
POWER
MASTER POWERDOWN LINE
1M
0.1
F
MANAGEMENT
UNIT
FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS
0.3V
-0.3V
-2.7V
2.7V
INVALID LEVEL - INVALID = 0
VALID RS-232 LEVEL - INVALID = 1
VALID RS-232 LEVEL - INVALID = 1
INDETERMINATE
INDETERMINATE
FIGURE 7. ENHANCED AUTOMATIC POWERDOWN LOGIC
30s
TIMER
S
R
FORCEOFF
AUTOSHDN
FORCEON
R_IN
T_IN
EDGE
DETECT
EDGE
DETECT
ICL3244
4-8
Emulating Standard Automatic Powerdown
If enhanced automatic powerdown isn't desired, the user can
implement the standard automatic powerdown feature
(mimics the function on the ICL3221/23/43) by connecting
the INVALID output to the FORCEON and FORCEOFF
inputs, as shown in Figure 9. After 30
s of invalid receiver
levels, INVALID switches low and drives the ICL3244 into a
forced powerdown condition. INVALID switches high as soon
as a receiver input senses a valid RS-232 level, forcing the
ICL3244 to power on. See the "INVALID DRIVING
FORCEON AND FORCEOFF" section of Table 2 for an
operational summary. This operational mode is perfect for
handheld devices that communicate with another computer
via a detachable cable. Detaching the cable allows the
internal receiver pull-down resistors to pull the inputs to GND
(an invalid RS-232 level), causing the 30
s timer to time-out
and drive the IC into powerdown. Reconnecting the cable
restores valid levels, causing the IC to power back up.
Hybrid Automatic Powerdown Options
For devices which communicate only through a detachable
cable, connecting INVALID to FORCEOFF (with FORCEON
= 0) may be a desirable configuration. While the cable is
attached INVALID and FORCEOFF remain high, so the
enhanced automatic powerdown logic powers down the RS-
232 device whenever there is 30 seconds of inactivity on the
receiver and transmitter inputs. Detaching the cable allows
the receiver inputs to drop to an invalid level (GND), so
INVALID switches low and forces the RS-232 device to
power down. The ICL3244 remains powered down until the
cable is reconnected (INVALID = FORCEOFF = 1) and a
transition occurs on a receiver or transmitter input (see
Figure 7). For immediate power up when the cable is
reattached, connect FORCEON to FORCEOFF through a
network similar to that shown in Figure 5.
Capacitor Selection
The charge pumps require 0.1
F capacitors for 3.3V
operation. For other supply voltages refer to Table 3 for
capacitor values. Do not use values smaller than those listed
in Table 3. Increasing the capacitor values (by a factor of 2)
reduces ripple on the transmitter outputs and slightly
reduces power consumption. C
2
, C
3
, and C
4
can be
increased without increasing C
1
's value, however, do not
increase C
1
without also increasing C
2
, C
3
, and C
4
to
maintain the proper ratios (C
1
to the other capacitors).
RECEIVER
INPUTS
TRANSMITTER
OUTPUTS
INVALID
OUTPUT
V+
V
CC
0
V-
t
INVL
t
INVH
FIGURE 8. ENHANCED AUTOMATIC POWERDOWN, AND INVALID TIMING DIAGRAMS
TRANSMITTER
INPUTS
t
WU
t
AUTOPWDN
t
AUTOPWDN
t
WU
INVALID
REGION
}
FIGURE 9. CONNECTIONS FOR AUTOMATIC POWERDOWN
WHEN NO VALID RECEIVER SIGNALS ARE
PRESENT
FORCEOFF
INV
ALID
CPU
I/O
FORCEON
ICL3244
UART
TABLE 3. REQUIRED CAPACITOR VALUES
V
CC
(V)
C
1
(
F)
C
2
, C
3
, C
4
(
F)
3.0 to 3.6
0.1
0.1
4.5 to 5.5
0.047
0.33
3.0 to 5.5
0.1
0.47
ICL3244
4-9
When using minimum required capacitor values, make sure
that capacitor values do not degrade excessively with
temperature. If in doubt, use capacitors with a larger nominal
value. The capacitor's equivalent series resistance (ESR)
usually rises at low temperatures and it influences the
amount of ripple on V+ and V-.
Power Supply Decoupling
In most circumstances a 0.1
F bypass capacitor is
adequate. In applications that are particularly sensitive to
power supply noise, decouple V
CC
to ground with a
capacitor of the same value as the charge-pump capacitor C
1
.
Connect the bypass capacitor as close as possible to the IC.
Transmitter Outputs when Exiting
Powerdown
Figure 10 shows the response of two transmitter outputs
when exiting powerdown mode. As they activate, the two
transmitter outputs properly go to opposite RS-232 levels,
with no glitching, ringing, nor undesirable transients. Each
transmitter is loaded with 3k
in parallel with 2500pF. Note
that the transmitters enable only when the magnitude of the
supplies exceed approximately 3V.
Mouse Driveability
The ICL3244 is specifically designed to power a serial
mouse while operating from low voltage supplies. Figure 11
shows the transmitter output voltages under increasing load
current. The on-chip switching regulator ensures the
transmitters will supply at least
5V during worst case
conditions (15mA for paralleled V+ transmitters, 7.3mA for
single V- transmitter).
High Data Rates
The ICL3244 maintains the RS-232
5V minimum
transmitter output voltages even at high data rates. Figure 12
details a transmitter loopback test circuit, and Figure 13
illustrates the loopback test result at 120kbps. For this test,
all transmitters were simultaneously driving RS-232 loads in
parallel with 1000pF, at 120kbps. Figure 14 shows the
loopback results for a single transmitter driving 1000pF and
an RS-232 load at 250kbps. The static transmitters were
also loaded with an RS-232 receiver.
TIME (20
s/DIV.)
T1
T2
2V/DIV
5V/DIV
V
CC
= +3.3V
FORCEOFF
FIGURE 10. TRANSMITTER OUTPUTS WHEN EXITING
POWERDOWN
C1 - C4 = 0.1
F
FIGURE 11. TRANSMITTER OUTPUT VOLTAGE vs LOAD
CURRENT (PER TRANSMITTER, i.e., DOUBLE
CURRENT AXIS FOR TOTAL V
OUT+
CURRENT)
TRANSMITTER OUTPUT V
O
L
T
A
GE (V)
LOAD CURRENT PER TRANSMITTER (mA)
0
2
4
6
8
10
-6
-4
-2
0
2
4
6
-5
-3
-1
1
3
5
1
3
5
7
9
V
OUT
+
V
OUT
-
V
CC
V
OUT
+
V
OUT
-
T1
T2
T3
V
CC
= 3.0V
ICL3244
ICL3244
V
CC
FORCEOFF
C
1
C
2
C
4
C
3
+
+
+
+
1000pF
V+
V-
5k
T
IN
R
OUT
C1+
C1-
C2+
C2-
R
IN
T
OUT
+
V
CC
0.1
F
V
CC
EN
SHDN OR
FIGURE 12. TRANSMITTER LOOPBACK TEST CIRCUIT
ICL3244
4-10
Interconnection with 3V and 5V Logic
The ICL3244 directly interfaces with most 5V logic families,
including ACT and HCT CMOS. See Table 4 for more
information on possible combinations of interconnections.
FIGURE 13. LOOPBACK TEST AT 120kbps
FIGURE 14. LOOPBACK TEST AT 250kbps
TABLE 4. LOGIC FAMILY COMPATIBILITY WITH VARIOUS
SUPPLY VOLTAGES
SYSTEM
POWER-SUPPLY
VOLTAGE (V)
V
CC
SUPPLY
VOLTAGE
(V)
COMPATIBILITY
3.3
3.3
Compatible with all CMOS
families.
5
5
Compatible with all TTL and
CMOS logic families.
5
3.3
Compatible with ACT and HCT
CMOS, and with TTL.
Incompatible with AC, HC, or
CD4000 CMOS.
T1
IN
T1
OUT
R1
OUT
5
s/DIV.
V
CC
= +3.3V
5V/DIV.
C1 - C4 = 0.1
F
T1
IN
T1
OUT
R1
OUT
2
s/DIV.
5V/DIV.
V
CC
= +3.3V
C1 - C4 = 0.1
F
ICL3244
4-11
Die Characteristics
DIE DIMENSIONS:
100 mils x 127 mils (2550
m x 3230
m)
METALLIZATION:
Type: Metal 1: AISi (1%)
Thickness: Metal 1: 8k
Type: Metal 2: AISi (1%)
Thickness: Metal 2: 10k
SUBSTRATE POTENTIAL (POWERED UP):
GND
PASSIVATION:
Type: Silox
Thickness: 13k
TRANSISTOR COUNT:
1109
PROCESS:
Si Gate CMOS
Typical Performance Curves
V
CC
= 3.3V, T
A
= 25
o
C
FIGURE 15. TRANSMITTER OUTPUT VOLTAGE vs LOAD
CAPACITANCE
FIGURE 16. SLEW RATE vs LOAD CAPACITANCE
FIGURE 17. SUPPLY CURRENT vs LOAD CAPACITANCE
WHEN TRANSMITTING DATA
FIGURE 18. SUPPLY CURRENT vs SUPPLY VOLTAGE
-6
-4
-2
0
2
4
6
1000
2000
3000
4000
5000
0
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT V
O
L
T
A
GE (V)
1 TRANSMITTER AT 250kbps
V
OUT
+
V
OUT
-
1 OR 2 TRANSMITTERS AT 30kbps
LOAD CAPACITANCE (pF)
SLEW RA
TE (V/
s)
0
1000
2000
3000
4000
5000
5
10
15
20
25
-SLEW
+SLEW
+SLEW
10
15
20
25
30
45
35
40
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
SUPPL
Y CURRENT (mA)
20kbps
250kbps
120kbps
SUPPL
Y CURRENT (mA)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0
0.5
1.0
1.5
2.0
SUPPLY VOLTAGE (V)
2.5
3.0
3.5
NO LOAD
ALL OUTPUTS STATIC
ICL3244
4-12
ICL3244
Shrink Small Outline Plastic Packages (SSOP)
NOTES:
1. Symbols are defined in the "MO Series Symbol List" in Section 2.2
of Publication Number 95.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension "D" does not include mold flash, protrusions or gate
burrs. Mold flash, protrusion and gate burrs shall not exceed
0.20mm (0.0078 inch) per side.
4. Dimension "E" does not include interlead flash or protrusions. Inter-
lead flash and protrusions shall not exceed 0.20mm (0.0078 inch)
per side.
5. The chamfer on the body is optional. If it is not present, a visual in-
dex feature must be located within the crosshatched area.
6. "L" is the length of terminal for soldering to a substrate.
7. "N" is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. Dimension "B" does not include dambar protrusion. Allowable dam-
bar protrusion shall be 0.13mm (0.005 inch) total in excess of "B"
dimension at maximum material condition.
10. Controlling dimension: MILLIMETER. Converted inch dimensions
are not necessarily exact.
INDEX
AREA
E
D
N
1
2
3
-B-
0.25(0.010)
C A
M
B S
e
-A-
L
B
M
-C-
A1
A
SEATING PLANE
0.10(0.004)
C
H
0.25(0.010)
B
M
M
0.25
0.010
GAUGE
PLANE
A2
M28.209
(JEDEC MO-150-AH ISSUE B)
28 LEAD SHRINK SMALL OUTLINE PLASTIC PACKAGE
SYMBOL
INCHES
MILLIMETERS
NOTES
MIN
MAX
MIN
MAX
A
-
0.078
-
2.00
-
A1
0.002
-
0.05
-
-
A2
0.065
0.072
1.65
1.85
-
B
0.009
0.014
0.22
0.38
9
C
0.004
0.009
0.09
0.25
-
D
0.390
0.413
9.90
10.50
3
E
0.197
0.220
5.00
5.60
4
e
0.026 BSC
0.65 BSC
-
H
0.292
0.322
7.40
8.20
-
L
0.022
0.037
0.55
0.95
6
N
28
28
7
0
o
8
o
0
o
8
o
-
Rev. 1 3/95
4-13
All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification.
Intersil semiconductor products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time with-
out notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see web site www.intersil.com
Sales Office Headquarters
NORTH AMERICA
Intersil Corporation
P. O. Box 883, Mail Stop 53-204
Melbourne, FL 32902
TEL: (321) 724-7000
FAX: (321) 724-7240
EUROPE
Intersil SA
Mercure Center
100, Rue de la Fusee
1130 Brussels, Belgium
TEL: (32) 2.724.2111
FAX: (32) 2.724.22.05
ASIA
Intersil Ltd.
8F-2, 96, Sec. 1, Chien-kuo North,
Taipei, Taiwan 104
Republic of China
TEL: 886-2-2515-8508
FAX: 886-2-2515-8369
ICL3244
Small Outline Plastic Packages (SOIC)
NOTES:
1. Symbols are defined in the "MO Series Symbol List" in Section 2.2
of Publication Number 95.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension "D" does not include mold flash, protrusions or gate
burrs. Mold flash, protrusion and gate burrs shall not exceed
0.15mm (0.006 inch) per side.
4. Dimension "E" does not include interlead flash or protrusions. In-
terlead flash and protrusions shall not exceed 0.25mm (0.010
inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual
index feature must be located within the crosshatched area.
6. "L" is the length of terminal for soldering to a substrate.
7. "N" is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. The lead width "B", as measured 0.36mm (0.014 inch) or greater
above the seating plane, shall not exceed a maximum value of
0.61mm (0.024 inch)
10. Controlling dimension: MILLIMETER. Converted inch dimen-
sions are not necessarily exact.
INDEX
AREA
E
D
N
1
2
3
-B-
0.25(0.010)
C A
M
B S
e
-A-
L
B
M
-C-
A1
A
SEATING PLANE
0.10(0.004)
h x 45
o
C
H
0.25(0.010)
B
M
M
M28.3
(JEDEC MS-013-AE ISSUE C)
28 LEAD WIDE BODY SMALL OUTLINE PLASTIC PACKAGE
SYMBOL
INCHES
MILLIMETERS
NOTES
MIN
MAX
MIN
MAX
A
0.0926
0.1043
2.35
2.65
-
A1
0.0040
0.0118
0.10
0.30
-
B
0.013
0.0200
0.33
0.51
9
C
0.0091
0.0125
0.23
0.32
-
D
0.6969
0.7125
17.70
18.10
3
E
0.2914
0.2992
7.40
7.60
4
e
0.05 BSC
1.27 BSC
-
H
0.394
0.419
10.00
10.65
-
h
0.01
0.029
0.25
0.75
5
L
0.016
0.050
0.40
1.27
6
N
28
28
7
0
o
8
o
0
o
8
o
-
Rev. 0 12/93
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