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MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
General Description
The MAX3221/MAX3223/MAX3243 achieve 1µA supply
current with Maxim’s revolutionary AutoShutdown™
feature. When the MAX3221/MAX3223/MAX3243 do not
sense a valid signal level on their receiver inputs, the onboard power supply and drivers shut down. This occurs
if the RS-232 cable is disconnected or if the transmitters
of the connected peripheral are turned off. The system
turns on again when a valid level is applied to any RS-232
receiver input.
The MAX3221/MAX3223/MAX3243 require only 0.1µF
capacitors in 3.3V operation, and can operate from input
voltages ranging from +3.0V to +5.5V.
A proprietary, high-efficiency, dual charge-pump power
supply and a low-dropout transmitter combine to deliver
true RS-232 performance from a single +3.0V to +5.5V
supply.
The MAX3221 is a 1-driver/1-receiver 16-pin SSOP
version of the 20-pin 2-driver/2-receiver MAX3223.
The MAX3243 is a 3-driver/5-receiver with a complementary
always-active receiver for external monitoring in a variety
of 28 pin packages. See Order Information table for
package offerings.
Applications
●●
●●
●●
●●
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Portable Diagnostics Equipment
Selector Guide
Benefits and Features
●● Integrated Charge Pump Circuitry Simplifies Power
Requirements
• Eliminates the Need for a ±12 Supply
• Operation From a Single +3.3V or +5V Supply
●● 1µA Supply Current in Shutdown Mode Saves Power
• AutoShutdown Feature is Enabled After No Activity
on Receiver Inputs for 30µs
• Software Control Option for Shutdown
Ordering Information
PART
MAX3221CAE
MAX3221CUE†
TEMP RANGE
PIN-PACKAGE
0°C to +70°C
16 SSOP
0°C to +70°C
16 TSSOP
MAX3221EAE
-40°C to +85°C
16 SSOP
MAX3221EUE†
-40°C to +85°C
16 TSSOP
MAX3223CPP
0°C to +70°C
20 Plastic DIP
MAX3223CAP
0°C to +70°C
20 SSOP
MAX3223CUP
0°C to +70°C
20 TSSOP
MAX3223EPP
-40°C to +85°C
20 Plastic DIP
MAX3223EAP
-40°C to +85°C
20 SSOP
MAX3223EUP
-40°C to +85°C
20 TSSOP
MAX3243CWI
0°C to +70°C
28 Wide SO
MAX3243CAI
0°C to +70°C
28 SSOP
MAX3243CUI
0°C to +70°C
28 TSSOP
MAX3243EWI
-40°C to +85°C
28 Wide SO
PART
Tx
Rx
VCC RANGE (V)
AutoShutdown
MAX3243EAI
-40°C to +85°C
28 SSOP
MAX3221
1
1
3.0 to 5.5
Yes
MAX3243EUI
-40°C to +85°C
28 TSSOP
MAX3223
2
2
3.0 to 5.5
Yes
MAX3243
3
5
3.0 to 5.5
Yes
Pin Configurations appear at end of data sheet.
Typical Operating Circuits appear at end of data sheet.
AutoShutdown and UCSP are trademarks of Maxim Integrated
Products, Inc.
19-0306; Rev 10; 5/19
†Future product—contact factory for availability.
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Absolute Maximum Ratings
VCC...........................................................................-0.3V to +6V
V+ (Note 1)...............................................................-0.3V to +7V
V- (Note 1)...............................................................+0.3V to -7V
V+ + |V-| (Note 1).................................................................+13V
Input Voltages
T_IN, FORCEOFF, FORCEON, EN (MAX3223)... -0.3V to +6V
R_IN.................................................................................±25V
Output Voltages
T_OUT...........................................................................±13.2V
R_OUT, INVALID................................... -0.3V to (VCC + 0.3V)
Short-Circuit Duration
T_OUT....................................................................Continuous
Continuous Power Dissipation (TA = +70°C)
16-Pin SSOP (derate 7.14mW/°C above +70°C).........571mW
16-Pin TSSOP (derate 6.70mW/°C above +70°C).......533mW
20-Pin Plastic DIP
(derate 11.11mW/°C above +70°C)..............................889mW
20-Pin SSOP (derate 8.00mW/°C above +70°C).........640mW
20-Pin TSSOP DIP
(derate 7.00mW/°C above +70°C)...............................559mW
28-Pin Wide SO (derate 12.50mW/°C above +70°C).........1W
28-Pin SSOP (derate 9.52mW/°C above +70°C).........762mW
28-Pin TSSOP (derate 8.70mW/°C above +70°C).......696mW
Operating Temperature Ranges
MAX32_ _C_ _....................................................0°C to +70°C
MAX32_ _E_ _................................................ -40°C to +85°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering, 10s).................................. +300°C
Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Electrical Characteristics
(VCC = +3.0V to +5.5V, C1–C4 = 0.1μF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
All R_IN open, FORCEON = GND,
FORCEOFF = VCC
1.0
10
µA
FORCEOFF = GND
1.0
10
µA
FORCEON = FORCEOFF = VCC,
no load
0.3
1.0
mA
0.8
V
DC CHARACTERISTICS
Supply Current, AutoShutdown
Supply Current, Shutdown
Supply Current,
AutoShutdown Disabled
VCC = 3.3V
or 5.0V,
TA = +25°C
LOGIC INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
T_IN, FORCEON, FORCEOFF, EN (MAX3223)
Input Logic Threshold High
T_IN, EN, FORCEON, FORCEOFF
Input Leakage Current
T_IN, EN, FORCEON, FORCEOFF
±0.01
±1.0
µA
±0.05
±10
µA
0.4
V
Output Leakage Current
Receivers disabled
Output Voltage Low
IOUT = 1.6mA
Output Voltage High
IOUT = -1.0mA
VCC = 3.3V
2.0
VCC = 5.0V
2.4
VCC 0.6
V
VCC 0.1
V
AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC)
Receiver Input Thresholds to
Transmitters Enabled
Figure 5
Receiver Input Thresholds to
Transmitters Disabled
1μA supply current, Figure 5
INVALID Output Voltage Low
IOUT = 1.6mA
INVALID Output Voltage High
IOUT = 1.0mA
Receiver Threshold to
Transmitters Enabled (tWU)
Figure 5
www.maximintegrated.com
Positive threshold
Negative threshold
2.7
-2.7
-0.3
+0.3
0.4
VCC - 0.6
V
V
V
V
250
µs
Maxim Integrated │ 2
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Electrical Characteristics (continued)
(VCC = +3.0V to +5.5V, C1–C4 = 0.1μF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Receiver Positive or Negative
Threshold to INVALID High (tINVH)
Figure 5
1
µs
Receiver Positive or Negative
Threshold to INVALID Low (tINVL)
Figure 5
30
µs
RECEIVER INPUTS
Input Voltage Range
-25
Input Threshold Low
TA = +25°C
Input Threshold High
TA = +25°C
0.6
1.2
VCC = 5.0V
0.8
1.5
1.5
2.4
VCC = 5.0V
1.8
2.4
0.3
TA = +25°C
3
5
V
V
VCC = 3.3V
Input Hysteresis
Input Resistance
+25
VCC = 3.3V
V
V
7
kΩ
TRANSMITTER OUTPUTS
Output Voltage Swing
All transmitter outputs loaded with 3kΩ to ground
±5.0
±5.4
V
Output Resistance
VCC = V+ = V- = 0V, transmitter output = ±2V
300
10M
Ω
Output Short-Circuit Current
Output Leakage Current
±35
VOUT = ±12V, VCC = 0V or 3.0V to 5.5V,
transmitters disabled
±60
mA
±25
μA
MOUSE DRIVEABILITY (MAX3243)
Transmitter Output Voltage
T1IN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩ to GND, T1OUT and
T2OUT loaded with 2.5mA each
±5
RL = 3kΩ, CL = 1000pF, one transmitter switching
120
V
TIMING CHARACTERISTICS
Maximum Data Rate
235
tPHL
0.3
tPLH
0.3
kbps
Receiver Propagation Delay
Receiver input to receiver output,
CL = 150pF
Receiver Output Enable Time
Normal operation
200
ns
Receiver Output Disable Time
Normal operation
200
ns
Transmitter Skew
│tPHL – tPLH│
Receiver Skew
│tPHL – tPLH│
Transition-Region Slew Rate
VCC = 3.3V, RL = 3kΩ to 7kΩ,
TA = +25°C, measured from
+3V to -3V or -3V to +3V
MAX3221/MAX3223
200
MAX3243
200
μs
1000
MAX3221/MAX3223
100
MAX3243
100
500
8.0
30
CL = 200pF to
2500pF
4
CL = 200pF to
1000pF
6
ns
ns
V/μs
30
Note 2: C1–C4 = 0.1μF, tested at 3.3V ±10%. C1 = 0.047μF, C2–C4 = 0.33μF, tested at 5.0V ±10%.
www.maximintegrated.com
Maxim Integrated │ 3
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Typical Operating Characteristics
14
-SLEW
12
10
+SLEW
8
6
-4
4
VOUT-
-5
2000
3000
4000
4000
MAX3243
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3243
SLEW RATE
vs. LOAD CAPACITANCE
1 TRANSMITTER AT 235kbps
2 TRANSMITTERS AT 30kbps
-2.5
VOUT-
-5.0
22
20
18
+SLEW
10
8
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
www.maximintegrated.com
5000
4
ALL OUTPUTS LOADED WITH 3kW +CL
0.1mF CHARGE-PUMP CAPACITORS
FOR ALL DATA RATES UP TO 235kbps
0
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
25
20
120kbps
20
15
15
10
20kbps
10
0
1000
2000
3000
5
4000
5000
MAX3243
SUPPLY CURRENT vs. LOAD
CAPACITANCE WHEN TRANSMITTING DATA
14
12
25
LOAD CAPACITANCE (pF)
-SLEW
16
30
5
5000
45
MAX3221/3223-05
24
6
0
3000
LOAD CAPACITANCE (pF)
5.0
0
2000
LOAD CAPACITANCE (pF)
VOUT+
2.5
0
150 500 1000
5000
235kbps
40
SUPPLY CURRENT (mA)
7.5
1000
MAX3221/3223-04
0
FOR DATA RATES UP TO 235kbps
2
30
235kbps
35
30
120kbps
25
20
20kbps
15
10
5
5000
0
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
Maxim Integrated │ 4
0
MAX3221 SUPPLY CURRENT (mA)
-2
-3
16
35
35
MAX3221/3223-06
18
MAX3221/3223-03
40
MAX3223 SUPPLY CURRENT (mA)
0
-1
-7.5
20
SLEW RATE (V/µs)
2
1
MAX3221/MAX3223
SUPPLY CURRENT vs. LOAD CAPACITANCE
WHEN TRANSMITTING DATA
MAX3221/3223-02
VOUT+
4
3
22
MAX3221/3223-01
6
5
-6
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3221/MAX3223
SLEW RATE
vs. LOAD CAPACITANCE
MAX3221/MAX3223
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
SLEW RATE (V/µs)
TRANSMITTER OUTPUT VOLTAGE (V)
(VCC = +3.3V, 235kbps data rate, 0.1μF capacitors, all transmitters loaded with 3kΩ, TA = +25°C, unless otherwise noted.)
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Pin Description
PIN
NAME
FUNCTION
MAX3221
MAX3223
MAX3243
1
1
—
EN
Receiver Enable Control. Drive low for normal operation. Drive high to
force the receiver outputs into a high-Z state.
5
5
1
C2+
Positive terminal of inverting charge-pump capacitor
6
6
2
C2-
Negative terminal of inverting charge-pump capacitor
7
7
3
V-
8
9, 16
4–8
R_IN
13
8, 17
9, 10, 11
T_OUT
11
12, 13
12, 13, 14
T_IN
TTL/CMOS Transmitter Inputs
9
10, 15
15–19
R_OUT
TTL/CMOS Receiver Outputs
—
—
20
R2OUTB
Noninverting Receiver Output—active in shutdown
10
11
21
INVALID
Output of the valid signal detector. Indicates if a valid RS-232 level is
present on receiver inputs logic “1”.
16
20
22
FORCEOFF
Drive low to shut down transmitters and on-board power supply.
This overrides all automatic circuitry and FORCEON (Table 1).
12
14
23
FORCEON
Drive high to override automatic circuitry keeping transmitters on
(FORCEOFF must be high) (Table 1).
4
4
24
C1-
Negative terminal of the voltage doubler charge-pump capacitor
14
18
25
GND
Ground
15
19
26
VCC
+3.0V to +5.5V Supply Voltage
3
3
27
V+
2
2
28
C1+
-5.5V generated by the charge pump
RS-232 Receiver Inputs
RS-232 Transmitter Outputs
+5.5V generated by the charge pump
Positive terminal of the voltage doubler charge-pump capacitor
Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3221/MAX3223/MAX3243’s internal power supply
consists of a regulated dual charge pump that provides
output voltages of +5.5V (doubling charge pump) and
-5.5V (inverting charge pump), regardless of the input
voltage (VCC) over the +3.0V to +5.5V range. The charge
pumps operate in a discontinuous mode: if the output
voltages are less than 5.5V, the charge pumps are
enabled; if the output voltages exceed 5.5V, the charge
pumps are disabled. Each charge pump requires a flying
capacitor (C1, C2) and a reservoir capacitor (C3, C4) to
generate the V+ and V- supplies.
RS-232 Transmitters
The transmitters are inverting level translators that
convert CMOS-logic levels to 5.0V EIA/TIA-232 levels.
They guarantee a 120kbps data rate with worst-case
loads of 3kΩ in parallel with 1000pF, providing compatibility with
PC-to-PC communication software (such as Laplink™).
Typically, the MAX3221/MAX3223/MAX3243 can operate
at data rates of 235kbps. Transmitters can be paralleled
to drive multiple receivers or mice (MAX3243). Figure 1
shows a complete system connection.
When FORCEOFF is driven to ground, or the auto-shutdown circuitry senses invalid voltage levels at all receiver
inputs, the transmitters are disabled and the outputs are
forced into a high-impedance state.
LapLink is a trademark of Traveling Software.
www.maximintegrated.com
Maxim Integrated │ 5
MAX3221/MAX3223/
MAX3243
POWER
MANAGEMENT
UNIT OR
KEYBOARD
CONTROLLER
+3V to +5.5V RS-232
Transceivers with AutoShutdown
FORCEOFF
VCC
FORCEON
INVALID
PROTECTION
DIODE
MAX3243
PREVIOUS
RS-232
VCC
I
Rx
5kΩ
UART
Tx
CPU
I/O
CHIP
WITH
UART
GND
SHDN = GND
RS-232
(a)
OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE
RECEIVER OUTPUT IN SHUTDOWN.
VCC
TO
µP
LOGIC
TRANSITION
DETECTOR
Figure 1. Interface Under Control of PMU
I
PROTECTION
DIODE
RS-232 Receivers
The MAX3221/MAX3223/MAX3243’s receivers convert
RS-232 signals to CMOS-logic output levels. All receivers have one inverting three-state output. In shutdown
(FORCEOFF = low) or in AutoShutdown, the MAX3221/
MAX3223’s receivers are active (Table 1). Driving EN high
places the receiver(s) in a high-impedance state. The
MAX3243’s receivers are high impedance when the part
is shut down.
The MAX3243 has an always-active complementary
output (R2OUTB). R2OUTB is an extra output that
monitors receiver activity while the other receivers
are high impedance. This allows Ring Indicator to be
monitored without forward biasing other devices
connected to the receiver outputs. This is ideal for
systems where VCC is set to 0V in shutdown to
accommodate peripherals, such as UARTs (Figure 2).
www.maximintegrated.com
MAX3243
R2OUTB
VCC
Rx
THREE-STATED
UART
Tx
GND
(b)
R2IN
R2OUT
T1IN
5kΩ
T1OUT
FORCEOFF = GND
NEW MAX3243: IN SHUTDOWN, R2OUTB IS USED TO MONITOR EXTERNAL
DEVICES AND R2OUT IS THREE STATED, ELIMINATING A CURRENT PATH
THROUGH THE UART'S PROTECTION DIODE.
Figure 2. The MAX3243 Detects RS-232 Activity When the
UART and Interface Are Shut Down.
Maxim Integrated │ 6
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Table 1a. MAX3221/MAX3223 FORCEOFF
and Enable Control Truth Table
FORCEOFF
EN
T_OUT
R_OUT
0
0
High-Z
Active
0
1
High-Z
High-Z
1
0
Active*
Active
1
1
Active*
High-Z
Table 1b. MAX3243 FORCEOFF Control
Truth Table
FORCEOFF
T_OUT
R_OUT
R2OUTB
0
High-Z
High-Z
Active
1
Active*
Active*
Active
*Note: If the part is in AutoShutdown mode (FORCEOFF
= VCC, FORCEON = GND), it is shut down if no valid RS-232
levels are present on all receiver inputs.
AutoShutdown
A 1µA supply current is achieved with Maxim’s new
AutoShutdown feature, which operates when FORCEON
is low and FORCEOFF is high. When the MAX3221/
MAX3223/MAX3243 sense no valid signal levels on all
receiver inputs for 30µs, the on-board power supply and
drivers are shut off, reducing supply current to 1µA. This
occurs if the RS-232 cable is disconnected or the connected peripheral transmitters are turned off. The system
turns on again when a valid level is applied to any RS-232
receiver input. As a result, the system saves power without changes to the existing BIOS or operating system.
When using AutoShutdown, the INVALID output is high
when the device is on and low when the device is shut
down. Because INVALID indicates the receiver inputs’
condition, it can be used in any mode (Figure 3).
Table 2 and Figure 3c summarize the MAX3221/
MAX3223/MAX3243 operating modes. FORCEON and
FORCEOFF override the automatic circuitry and force the
transceiver into its normal operating state or into its lowpower standby state. When neither control is asserted,
the IC selects between these states automatically based
on receiver input levels. Figures 3a, 3b, and 5a depict
valid and invalid RS-232 receiver levels.
A mouse or other system with AutoShutdown may need
time to wake up. Figure 4 shows a circuit that forces the
transmitters on for 100ms, allowing enough time for the
other system to realize that the MAX3221/MAX3223/
www.maximintegrated.com
+0.3V
R_IN
TO MAX32_ _
POWER SUPPLY
AND TRANSMITTERS
30µs
COUNTER
R
-0.3V
INVALID
* TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1µA IF
ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30µs.
Figure 3a. MAX32_ _ Entering 1μA Supply Mode Through
AutoShutdown
+2.7V
R_IN
TO MAX32_ _
POWER SUPPLY
30µs
COUNTER
R
-2.7V
INVALID
* TRANSMITTERS ARE ENABLED IF:
ANY RECEIVER INPUT IS GREATER THAN +2.7V OR LESS THAN -2.7V.
ANY RECEIVER INPUT HAS BEEN BETWEEN +0.3V AND -0.3V FOR LESS THAN 30µs.
Figure 3b. MAX32_ _ with Transmitters Enabled Using
AutoShutdown
FORCEOFF
POWER DOWN
FORCEON
INVALID
INVALID IS AN INTERNALLY GENERATED SIGNAL
THAT IS USED BY THE AUTOSHUTDOWN LOGIC
AND APPEARS AS AN OUTPUT OF THE DEVICE.
POWER DOWN IS ONLY AN INTERNAL SIGNAL.
IT CONTROLS THE OPERATIONAL STATUS OF
THE TRANSMITTERS AND THE POWER SUPPLIES.
Figure 3c. AutoShutdown Logic
POWER
MANAGEMENT
UNIT
MASTER SHDN LINE
0.1µF
1MΩ
FORCEOFF FORCEON
MAX3221
MAX3223
MAX3243
Figure 4. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System
Maxim Integrated │ 7
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Table 2. AutoShutdown Logic
RS-232 SIGNAL
PRESENT AT
RECEIVER INPUT
FORCEOFF
INPUT
FORCEON
INPUT
INVALID
INPUT
Yes
H
X
H
Normal Operation
No
H
H
L
Normal Operation (Forced On)
No
H
L
L
Shutdown (AutoShutdown)
Yes
L
X
H
Shutdown (Forced Off)
No
L
X
L
Shutdown (Forced Off)
TRANSCEIVER
STATUS
MAX3243 is awake. If the other system outputs valid
RS-232 signals within that time, the RS-232 ports on both
systems remain enabled.
Software-Controlled Shutdown
If direct software control is desired, INVALID can be used
to indicate DTR or Ring Indicator signal. Tie FORCEOFF
and FORCEON together to bypass AutoShutdown so the
line acts like a SHDN input.
Applications Information
TRANSMITTERS ENABLED, INVALID HIGH
RECEIVER INPUT LEVELS
When shut down, the device’s charge pumps are turned
off, V+ decays to VCC, V- decays to ground, and
the transmitter outputs are disabled (high impedance).
The time required to exit shutdown is typically 100µs
(Figure 5b).
+2.7V
INDETERMINATE
+0.3V
0V
-0.3V
AUTOSHUTDOWN, TRANSMITTERS DISABLED,
1µA SUPPLY CURRENT, INVALID LOW
INDETERMINATE
-2.7V
TRANSMITTERS ENABLED, INVALID HIGH
(a)
Capacitor Selection
The capacitor type used for C1–C4 is not critical for
proper operation; either polarized or nonpolarized capacitors may be used. The charge pump requires 0.1µF
capacitors for 3.3V operation. For other supply voltages,
refer to Table 3 for required capacitor values. Do not use
values smaller than those listed in Table 3. Increasing
the capacitor values (e.g., by a factor of 2) reduces ripple
on the transmitter outputs and slightly reduces power
consumption. C2, C3, and C4 can be increased without
changing C1’s value. However, do not increase C1
without also increasing the values of C2, C3, and
C4 to maintain the proper ratios (C1 to the other
capacitors).
When using the minimum required capacitor values,
make sure the capacitor value does 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
influences the amount of ripple on V+ and V-.
www.maximintegrated.com
RECEIVER
INPUT
VOLTAGE
(V)
INVALID
REGION
VCC
INVALID
OUTPUT
(V)
0
tINVL
tINVH
tWU
V+
VCC
0
V(b)
Figure 5. AutoShutdown Trip Levels
Maxim Integrated │ 8
T2
2V/div
T1
50µs/div
VCC = +3.3V
C1–C4 = 0.1µF
6
5
4
3
VOUT+
VCC = 3.0V
2
1
T1
0
-1
T2
MAX3222-04
5V/div
+3V to +5.5V RS-232
Transceivers with AutoShutdown
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3221/MAX3223/
MAX3243
VOUT+
-2
-3
VCC
VOUT-
T3
VOUT-
-4
-5
-6
0
1
2
3
4
5
6
7
LOAD CURRENT PER TRANSMITTER (mA)
Figure 6. Transmitter Outputs When Exiting Shutdown or
Powering Up
Figure 7a. MAX3243 Transmitter Output Voltage vs. Load
Current per Transmitter
Power-Supply Decoupling
serial mice and met their respective current and voltage
requirements. Figure 7a shows the transmitter outputs
under increasing load current. The MAX3243’s switching
regulator ensures the transmitters will supply at least
±5V during worst-case conditions. The AutoShutdown
feature does not work with a mouse, so FORCEOFF and
FORCEON should be connected to VCC.
In most circumstances a 0.1µF bypass capacitor is adequate.
In applications that are sensitive to power-supply noise,
decouple VCC to ground with a capacitor of the same
value as the charge-pump capacitor C1. Connect bypass
capacitors as close to the IC as possible.
Transmitter Outputs
when Exiting Shutdown
Figure 6 shows two transmitter outputs when exiting
shutdown mode. As they become active, the two transmitter outputs are shown going to opposite RS-232
levels. Each transmitter is loaded with 3kΩ in parallel
with 2500pF. The transmitter outputs display no ringing
or undesirable transients as they come out of shutdown.
Note that the transmitters are enabled only when the
magnitude of V- exceeds approximately 3V. Figure 7a
shows the MAX3243’s transmitter output voltage vs.
current per transmitter. Figure 7b is a mouse driver test
circuit.
Mouse Driveability (MAX3243)
The MAX3243 has been specifically designed to power
serial mice while operating from low-voltage power
supplies. It has been tested with samples of ten major
mouse models from six manufacturers including the
leading three: Logitech (5 models), Mouse Systems,
and Microsoft. The MAX3243 successfully drove all
www.maximintegrated.com
High Data Rates
The MAX3221/MAX3223/MAX3243 maintain the RS-232
±5.0V minimum transmitter output voltage even at high
data rates. Figure 8 shows a transmitter loopback test
circuit. Figure 9 shows a loopback test result at 120kbps,
and Figure 10 shows the same test at 235kbps. For
Figure 9, all three transmitters were driv-en simultaneously
at 120kbps into RS-232 loads in parallel with 1000pF. For
Figure 10, a single transmitter was driven at 235kbps,
but all three transmitters were loaded with an RS-232
receiver in parallel with 1000pF.
Interconnection with
3V and 5V Logic
The MAX3221/MAX3223/MAX3243 can directly interface
with various 5V logic families, including ACT and HCT
CMOS. See Table 4 for more information on possible
combinations of interconnections.
Maxim Integrated │ 9
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
+3.3V
26
0.1µF
28
C1
0.1µF
24
1
C2
0.1µF
2
LOGIC
INPUTS
C1+
C1-
VCC
V+
MAX3243
C2+
V-
27
C3
0.1µF
3
C2-
COMPUTER SERIAL PORT
C4
0.1µF
14
T1IN
T1OUT
9
+V
13
T2IN
T2OUT
10
+V
12
T3IN
T3OUT
11
-V
20
R2OUTB
19
R1OUT
GND
R1IN
Tx
4
5kΩ
18
R2OUT
R2IN
LOGIC
OUTPUTS
5
5kΩ
17
R3OUT
R3IN
6
RS-232
INPUTS
5kΩ
16
R4OUT
R4IN
7
5kΩ
15
23
VCC
TO POWER
MANAGEMENT
UNIT
22
21
R5OUT
R5IN
8
SERIAL
MOUSE
5kΩ
FORCEON
FORCEOFF
INVALID
GND
25
Figure 7b. Mouse Driver Test Circuit
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Maxim Integrated │ 10
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Table 3. Required Capacitor Values
VCC
(V)
C1
(μF)
C2, C3, C4
(μF)
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
VCC
0.1µF
VCC
C1+
C1
C1C2+
C2
MAX3221
MAX3223
MAX3243
Table 4. Logic Family Compatibility with
Various Supply Voltages
C4
R_ IN
EN (MAX3221/3)
FORCEOFF
C3
T_ OUT
R_ OUT
VCC
V-
C2T_ IN
0V
V+
5kΩ
1000pF
GND
SYSTEM
POWERSUPPLY
VOLTAGE
(V)
VCC SUPPLY
VOLTAGE
(V)
3.3
3.3
5
5
Compatible with all TTL and
CMOS-logic families.
3.3
Compatible with ACT and
HCT CMOS, and with TTL.
Incompatible with AC, HC,
or CD4000 CMOS.
5
Figure 8. Loopback Test Circuit
COMPATIBILITY
Compatible with all CMOS
families.
T1IN
5V/div
T1IN
5V/div
T1OUT
5V/div
T1OUT
5V/div
R1OUT
5V/div
R1OUT
5V/div
2µs/div
5µs/div
VCC = +3.3V, 120kbps
C1–C4 = 0.1µF
Figure 9. Loopback Test Result at 120kbps
www.maximintegrated.com
VCC = +3.3V, 235kbps
C1–C4 = 0.1µF
Figure 10. Loopback Test Result at 235kbps
Maxim Integrated │ 11
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Typical Operating Circuits
+3.3V
15
0.1µF
C5
2 C1+
C1
0.1µF
4 C15
C2
0.1µF
6
C2+
VCC
V+
MAX3221
V-
3
C3
0.1µF
7
C2-
11 T1IN
28 C1+
C1
0.1µF
1
2
5kΩ
INVALID 10
1 EN
12
FORCEOFF 16
FORCEON
GND
TO POWER
MANAGEMENT
UNIT
LOGIC
INPUTS
VCC
TTL/CMOS
INPUTS
2 C1+
4 C1-
6
C2+
V+
MAX3223
V-
C3
0.1µF
7
13 T1IN
T1OUT 17
12 T2IN
T2OUT 8
C4
0.1µF
T1OUT 9
13 T2IN
T2OUT 10
12 T3IN
T3OUT 11
C4
0.1µF
RS-232
OUTPUTS
R1IN 4
INVALID 11
FORCEOFF 20
R2IN
RS-232
INPUTS
5
5kΩ
17 R3OUT
R3IN 6
RS-232
INPUTS
R4IN 7
5kΩ
15 R5OUT
23
VCC
TO POWER
MANAGEMENT UNIT
5kΩ
GND
3
5kΩ
RS-232
OUTPUTS
R2IN 9
FORCEON
V-
14 T1IN
16 R4OUT
5kΩ
14
LOGIC
OUTPUTS
R1IN 16
1 EN
C3
0.1µF
C2-
18 R2OUT
3
C2-
10 R2OUT
27
5kΩ
VCC
15 R1OUT
TTL/CMOS
OUTPUTS
MAX3243
19
0.1µF
5
C2
0.1µF
C2+
19 R1OUT
+3.3V
C1
0.1µF
V+
20 R2OUTB
14
C5
VCC
24 C1-
C2
0.1µF
R1IN 8
26
0.1µF
C4
0.1µF
T1OUT 13
9 R1OUT
+3.3V
22
R5IN 8
5kΩ
FORCEON
FORCEOFF
21 INVALID
GND
25
TO POWER
MANAGEMENT
UNIT
VCC
18
www.maximintegrated.com
Maxim Integrated │ 12
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim
PART
POWERSUPPLY
VOLTAGE
(V)
NUMBER OF
TRANSMITTERS/
RECEIVERS
NUMBER OF
RECEIVERS
ACTIVE IN
SHUTDOWN
GUARANTEED
DATA RATE
(kbps)
EIA/
TIA-232
OR 562
MAX212
3.0 to 3.6
3/5
5
120
232
Drives mice
MAX218
1.8 to 4.25
2/2
2
120
232
Operates directly from batteries
without a voltage regulator
MAX562
2.7 to 5.25
3/5
5
230
562
230kbps guaranteed data rate
MAX563
3.0 to 3.6
2/2
2
120
562
0.1μF capacitors
MAX3212
2.7 to 3.6
3/5
5
235
232
AutoShutdown, complementary
receiver, drives mice, transient
detection
MAX3221
3.0 to 5.5
1/1
1
120
232
0.1μF capacitors, 16-pin SSOP
MAX3222
3.0 to 5.5
2/2
2
120
232
0.1μF capacitors, MAX242 pinout
MAX3223
3.0 to 5.5
2/2
2
120
232
0.1μF capacitors, AutoShutdown
MAX3232
3.0 to 5.5
2/2
N/A
120
232
0.1μF capacitors, MAX232 pinout
MAX3241
3.0 to 5.5
3/5
5
120
232
0.1μF capacitors, 2 complementary
receivers, drives mice
MAX3243
3.0 to 5.5
3/5
1
120
232
0.1μF capacitors, AutoShutdown
complementary receiver, drives
mice
www.maximintegrated.com
FEATURES
Maxim Integrated │ 13
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Pin Configurations
TOP VIEW
EN 1
16 FORCEOFF
EN 1
C1+ 2
15 VCC
V+ 3
14 GND
C1- 4
MAX3221
C2+ 5
12 FORCEON
C2- 6
11 T1IN
V- 7
19 VCC
V+ 3
18 GND
C1- 4
17 T1OUT
C2- 6
V- 7
10 INVALID
9 R1OUT
R1IN 8
C1+ 2
C2+ 5
13 T1OUT
20 FORCEOFF
MAX3223
16 R1IN
15 R1OUT
14 FORCEON
T2OUT 8
13 T1IN
R2IN 9
12 T2IN
R2OUT 10
SSOP/TSSOP
11 INVALID
DIP/SSOP/TSSOP
C2+ 1
28 C1+
C2- 2
27 V+
V- 3
26 VCC
R1IN 4
25 GND
R2IN 5
24 C1-
R3IN 6
MAX3243
R4IN 7
23 FORCEON
22 FORCEOFF
R5IN 8
21 INVALID
T1OUT 9
20 R2OUTB
T2OUT 10
19 R1OUT
T3OUT 11
18 R2OUT
T3IN 12
17 R3OUT
T2IN 13
16 R4OUT
T1IN 14
15 R5OUT
SO/SSOP/TSSOP
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Maxim Integrated │ 14
MAX3221/MAX3223/
MAX3243
+3V to +5.5V RS-232
Transceivers with AutoShutdown
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE
TYPE
THERMAL RESISTANCE
(SINGLE LAYER BOARD)
THERMAL RESISTANCE
(MULTI LAYER BOARD)
θJA (°C/W)
θJC (°C/W)
θJA (°C/W)
θJC (°C/W)
90-0106
140
34
86
33
90-0117
106
27
90
27
—
90
30
NA
NA
90-0094
125
33
84
32
91
20
73.8
20
80
18
59
18
110
25
67.1
25
78
13
71.6
13
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
16 SSOP
A16+2
21-0056
16 TSSOP
U16+1
21-0066
20 Plastic DIP
P20+2
21-0043
20 SSOP
A20+1
21-0056
20 TSSOP
U20+2
21-0066
90-0116
28 Wide SO
W28+1
21-0042
90-0109
28 SSOP
A28+1
21-0056
90-0095
28 TSSOP
U28+2
21-0066
90-0171
www.maximintegrated.com
Maxim Integrated │ 15
MAX3221/MAX3223/
MAX3243
REVISION
NUMBER
REVISION
DATE
9
1/15
10
5/2019
+3V to +5.5V RS-232
Transceivers with AutoShutdown
PAGES
CHANGED
DESCRIPTION
Updated General Description and Benefits and Features sections
1
Added Package Information table
15
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2019 Maxim Integrated Products, Inc. │ 16
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