General Description
The MAX3221E/MAX3223E/MAX3243E are 3V-powered
EIA/TIA-232 and V.28/V.24 communications interfaces
with automatic shutdown/wakeup features, high data-
rate capabilities, and enhanced electrostatic discharge
(ESD) protection. All transmitter outputs and receiver
inputs are protected to ±15kV using IEC 1000-4-2 Air-
Gap Discharge, to ±8kV using IEC 1000-4-2 Contact
Discharge, and to ±15kV using the Human Body Model.
The MAX3221E/MAX3223E/MAX3243E achieve a
1µA supply current with Maxim’s revolutionary
AutoShutdown™ feature. They save power without
changes to the existing BIOS or operating system by enter-
ing low-power shutdown mode when the RS-232 cable is
disconnected, or when the transmitters of the connected
peripherals are off.
The transceivers have a proprietary low-dropout trans-
mitter output stage, delivering true RS-232 performance
from a +3.0V to +5.5V supply with a dual charge pump.
The charge pump requires only four small 0.1µF capaci-
tors for operation from a +3.3V supply. Each device is
guaranteed to run at data rates of 250kbps while main-
taining RS-232 output levels.
The MAX3221E contains just one driver and one receiver,
making it the smallest single-supply RS-232 transceiver.
The MAX3223E has two drivers and two receivers. The
MAX3243E is a complete 3-driver/5-receiver serial port
ideal for notebook or subnotebook computers. It also
includes two noninverting receiver outputs that are always
active, allowing external devices to be monitored without
forward biasing the protection diodes in circuitry that may
be powered down.
The MAX3221E, MAX3223E, and MAX3243E are avail-
able in space-saving TQFN, SSOP, and TSSOP pack-
ages.
Applications
Notebook, Subnotebook, and Palmtop Computers
Cellular Phones
Battery-Powered Equipment
Handheld Equipment
Peripherals
Printers
Next Generation Device Features
♦♦For Space-Constrained Applications:
MAX3228E/MAX3229E: ±15kV ESD-Protected, +2.5V
to +5.5V RS-232 Transceivers in UCSP™
MAX3222E/MAX3232E/MAX3237E/MAX3241E/
MAX3246E: ±15kV ESD-Protected Down to 10nA,
+3.0V to +5.5V, Up to 1Mbps, True RS-232
Transceivers (MAX3246E Available in a UCSP
Package)
♦♦For Data Cable Applications:
MAX3380E/MAX3381E: +2.35V to +5.5V, 1µA,
2Tx/2Rx RS-232 Transceivers with ±15kV ESD-
Protected I/O and Logic Pins
MAX3221E/MAX3223E/MAX3243E
†
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
________________________________________________________________
Maxim Integrated Products
1
19-1283; Rev 6; 9/05
PART
MAX3221ECUE
MAX3221EEAE -40°C to +85°C
0°C to +70°C
TEMP
RANGE
PIN-
PACKAGE
16 TSSOP
16 SSOP
AutoShutdown and UCSP are trademarks of Maxim Integrated Products, Inc.
†
C.
Pin Configurations appear at end of data sheet.
Typical Operating Circuits appear at end of data sheet.
* Exposed paddle.
Ordering Information continued at end of data sheet.
MAX3223EEPP -40°C to +85°C20 Plastic DIP
MAX3223EEAP -40°C to +85°C20 SSOP
MAX3221EETE
MAX3223ECAP 0°C to +70°C
-40°C to +85°C16 Thin QFN-EP
(5mm x 5mm)
20 SSOP
Ordering Information
Selector Guide
MAX3223ECUP 0°C to +70°C20 TSSOP
MAX3223EEUP -40°C to +85°C20 TSSOP
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
PKG
CODE
—
—
—
—
—
T1655-2
—
—
MAX3221ECAE 0°C to +70°C16 SSOP —
MAX3221ECTE 0°C to +70°C16 Thin QFN-EP
(5mm x 5mm) T1655-2
MAX3221EEUE -40°C to +85°C16 TSSOP —
MAX3223ECPP 0°C to +70°C20 Plastic DIP —
MAX3223ECTP 0°C to +70°C20 Thin QFN-EP*
(5mm x 5mm) T2055-5
MAX3223EETP -40°C to +85°C20 Thin QFN-EP*
(5mm x 5mm) T2055-5
PART
NO. OF
DRIVERS/
RECEIVERS
VCC
RANGE
(V)
AutoShutdown
MAX3221E 1/1 +3.0 to +5.5
MAX3223E 2/2 +3.0 to +5.5
MAX3243E 3/5 +3.0 to +5.5
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.)
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.
VCC to GND..............................................................-0.3V to +6V
V+ to GND (Note 1) ..................................................-0.3V to +7V
V- to GND (Note 1) ...................................................+0.3V to -7V
V+ + |V-|(Note 1) .................................................................+13V
Input Voltages
T_IN, EN, FORCEON, FORCEOFF to GND ............-0.3V to +6V
R_IN to GND ......................................................................±25V
Output Voltages
T_OUT to GND................................................................±13.2V
R_OUT, R2OUTB, INVALID to GND.........-0.3V to (VCC + 0.3V)
Short-Circuit Duration
T_OUT to GND .........................................................Continuous
Continuous Power Dissipation (TA= +70°C)
16-Pin SSOP (derate 7.14mW/°C above +70°C) ...........571mW
16-Pin TSSOP (derate 9.4mW/°C above +70°C) ........754.7mW
16-Pin TQFN (derate 20.8mW/°C above +70°C) ......1666.7mW
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 (derate 10.9mW/°C above +70°C) .........879mW
20-Pin TQFN (derate 21.3mW/°C above +70°C) ......1702.1mW
28-Pin SSOP (derate 9.52mW/°C above +70°C)............762mW
28-Pin TSSOP (derate 12.8mW/°C above +70°C) .......1026mW
Operating Temperature Ranges
MAX32_ _EC_ _ ....................................................0°C to +70°C
MAX32_ _EE_ _..................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°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.
VCC = 5.0V
RECEIVER OUTPUTS
AutoShutdown (FORCEON = GND, FORCEOFF = VCC)
LOGIC INPUTS
DC CHARACTERISTICS (VCC = 3.3V or 5.0V, TA= +25°C)
R_OUT receivers disabledOutput Leakage Current ±0.05 ±10 µA
Negative threshold
Positive threshold
Figure 5a
VCC = 3.3V
T_IN, EN, FORCEON,
FORCEOFF
CONDITIONS
IOUT = -1.0mA
IOUT = 1.6mA
Figure 5a
IOUT = -1.0mA
IOUT = 1.6mA
T_IN, EN, FORCEON, FORCEOFF
FORCEON = FORCEOFF = VCC,
no load
FORCEOFF = GND, all R_IN = GND
FORCEON = GND,
FORCEOFF = VCC, all R_IN open
VCC - 0.6 V
INVALID Output Voltage High
-0.3 0.3 V
Receiver Input Threshold to
INVALID Output Low
0.4 V
INVALID Output Voltage Low
-2.7 V
Receiver Input Threshold to
INVALID Output High
2.7
0.3 1 mA
Supply Current,
AutoShutdown Disabled
1.0 10 µASupply Current, Shutdown
Supply Current, AutoShutdown
2.0
PARAMETER MIN TYP MAX UNITS
Input Logic Threshold Low 0.8 V
1.0 10 µA
Input Logic Threshold High 2.4 V
Output Voltage Low 0.4 V
Output Voltage High VCC - 0.6 VCC - 0.1 V
SYMBOL
Transmitter Input Hysteresis 0.5 V
T_IN, EN, FORCEON, FORCEOFF
Input Leakage Current ±0.01 ±1 µA
kV
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
_______________________________________________________________________________________ 3
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 MIN TYP MAX UNITS
±25
Output Short-Circuit Current ±60 mA
Output Resistance 300 10M Ω
Output Leakage Current µA
Input Threshold Low 0.6 1.2 V
±5 ±5.4Output Voltage Swing V
CONDITIONS
VCC = V+ = V- = 0, TOUT = ±2V
VOUT = ±12V, VCC = 0 or 3V to
5.5V, transmitters disabled
All transmitter outputs loaded with
3kΩto ground
Receiver Positive or Negative
Threshold to INVALID High 1µsVCC = 5V, Figure 5b
Input Hysteresis 0.5 V
Input Threshold High V
Input Resistance 35 7kΩ
0.8 1.5
1.8 2.4
1.5 2.4
TA= +25°C
TA= +25°C
±5.0Transmitter Output Voltage V
T1IN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩto GND,
T1OUT and T2OUT loaded with
2.5mA each
tINVH
SYMBOL
VCC = 3.3V
VCC = 5.0V
VCC = 3.3V
VCC = 5.0V
±15IEC 1000-4-2 Air-Gap Discharge
Receiver Positive or Negative
Threshold to INVALID Low 30 µsVCC = 5V, Figure 5btINVL
Input Voltage Range -25 25 V
Receiver or Transmitter Edge to
Transmitters Enabled 100 µsVCC = 5V, Figure 5btWU
Input Voltage Range -25 25 V
±8IEC 1000-4-2 Contact Discharge
R_IN, T_OUT
±15Human Body Model
kV
RECEIVER INPUTS
TRANSMITTER OUTPUTS
MOUSE DRIVEABILITY (MAX3243E)
ESD PROTECTION
Typical Operating Characteristics
(VCC = +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩand CL, TA = +25°C, unless otherwise noted.)
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
0 1000 2000 3000 4000 5000
MAX3221E/MAX3223E
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3221E-01
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
VOUT+
T1 TRANSMITTING AT 250kbps
T2 (MAX3223E) TRANSMITTING AT 15.6kbps
VOUT-
0
2
4
6
8
10
12
14
16
0 1000 2000 3000 4000 5000
MAX3221E/MAX3223E
SLEW RATE vs. LOAD CAPACITANCE
MAX3221-TOC2
LOAD CAPACITANCE (pF)
SLEW RATE (V/μs)
-SLEW
+SLEW
FOR DATA RATES UP TO 250kbps
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
4 _______________________________________________________________________________________
TIMING CHARACTERISTICS—MAX3221E/MAX3223E/MAX3243E
(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.)
Note 2: C1–C4 = 0.1µF, tested at 3.3V ±10%. C1 = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%.
Note 3: Transmitter skew is measured at the transmitter zero cross points.
tPLH
RL= 3kΩ, CL= 1000pF,
one transmitter switching
tPHL
SYMBOL
⏐tPHL - tPLH ⏐
⏐tPHL - tPLH ⏐
Receiver Output Disable Time ns
CONDITIONS
µs
0.15
Receiver Propagation Delay
CL= 150pF to
1000pF
kbps
UNITSMIN TYP MAXPARAMETER
(Note 3)
ns50Receiver Skew
ns100Transmitter Skew
VCC = 3.3V,
RL= 3kΩto 7kΩ,
TA= +25°C,
measured from +3V
to -3V or
-3V to +3V, one
transmitter switching
V/µsTransition-Region Slew Rate 630
CL= 150pF
250
0.15
Maximum Data Rate
nsNormal operationReceiver Output Enable Time
200Normal operation
200
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
_______________________________________________________________________________________
5
Typical Operating Characteristics (continued)
(VCC = +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩand CL, TA= +25°C, unless otherwise noted.)
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
0
MAX3243E
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3224E-04
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
2000 30001000 4000 5000
1 TRANSMITTER AT 250kbps
2 TRANSMITTERS AT 15.6kbps
VOUT+
VOUT-
0
4
2
8
6
12
10
14
0 1000 2000 3000 4000 5000
MAX3243E
SLEW RATE vs. LOAD CAPACITANCE
MAX3243E-05
LOAD CAPACITANCE (pF)
SLEW RATE (V/μs)
0
30
20
10
40
50
60
0 20001000 3000 4000 5000
MAX3243E
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3243E-06
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
250kbps
120kbps
20kbps
T1 TRANSMITTING AT 250kbps
T2 (MAX3223E) TRANSMITTING AT 15.6kbps
0
5
10
15
20
25
30
35
40
45
0 20001000 3000 4000 5000
MAX3221E/MAX3223E
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3224E-03
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
250kbps
120kbps
20kbps
T1 TRANSMITTING AT 250kbps
T2 (MAX3223E) TRANSMITTING AT 15.6kbps
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
6 _______________________________________________________________________________________
Pin Description
PIN
MAX3221E MAX3223E MAX3243E
TQFN SSOP/
TSSOP TQFN
DIP/
SSOP/
TSSOP
SO/
SSOP/
TSSOP
THIN
QFN
NAME FUNCTION
14 1 19 1 — 22 EN
Receiver Enable Control. Drive low for normal
operation. Drive high to force the receiver outputs
(R_OUT) into a high-impedance state.
16 2 1 2 28 28 C1+
Positive terminal of the voltage doubler Charge-Pump
Capacitor
15 3 20 3 27 27 V+ +5.5V generated by the charge pump
1 4 2 4 24 23 C1-
Negative terminal of the voltage doubler Charge-Pump
Capacitor
2 5 3 5 1 29 C2+ Positive terminal of inverting Charge-Pump Capacitor
3 6 4 6 2 30 C2- Negative terminal of inverting Charge-Pump Capacitor
4 7 5 7 3 31 V- -5.5V generated by the charge pump
5 8 7, 14 9, 16 4-8 1-5 R_IN RS-232 Receiver Inputs
6 9 8, 13 10, 15 15-19
13, 14,
15, 17,
18
R_OUT TTL/CMOS Receiver Outputs
7 10 9 11 21 — INVALID
Output of the Valid Signal Detector. INVALID is enabled
high if a valid RS-232 level is present on any receiver
input.
8 11 10, 11 12, 13 12, 13,
14
10, 11,
12 T_IN TTL/CMOS Transmitter Inputs
9 12 12 14 23 — FORCEON
Drive high to override automatic circuitry keeping
transmitters and charge pump on (FORCEOFF must be
high) (Table 1).
10 13 6, 15 8, 17 9, 10,
11 6, 7, 8 T_OUT RS-232 Transmitter Outputs
— — — — 20 19 R2OUTB
TTL/CMOS Noninverting Complementary Receiver
Output. Always active.
11 14 16 18 25 24 GND Ground
12 15 17 19 26 26 VCC +3.0V to +5.5V Supply Voltage
13 16 18 20 22 —
FORCEOFF
Force-Off Input, active low. Drive low to shut down
transmitters, receivers (MAX3243E, except R2OUTB),
and on-board charge pump. This overrides all
automatic circuitry and FORCEON (Table 1).
— — — — — 21
SHDN Shutdown Control, Active Low
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
_______________________________________________________________________________________ 7
_______________Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3221E/MAX3223E/MAX3243E’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), over the
+3.0V to +5.5V VCC range. The charge pumps operate
in 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 con-
vert CMOS-logic levels to 5.0V EIA/TIA-232 levels. They
guarantee a 250kbps data rate with worst-case loads
of 3kΩin parallel with 1000pF, providing compatibility
with PC-to-PC communication software such as
LapLink™. Transmitters can be paralleled to drive mul-
tiple receivers. The MAX3243E has been specifically
designed to drive serial mice. Figure 1 shows a com-
plete system connection. When FORCEOFF is driven to
ground, or the AutoShutdown circuitry senses invalid
voltage levels on all receiver inputs, the transmitters are
disabled and the outputs are forced into a high-imped-
ance state. When powered off or shut down, the output
can be driven up to ±12V. The transmitter inputs do not
have pull-up resistors.
Pin Description (continued)
PIN
MAX3221E MAX3223E MAX3243E
TQFN SSOP/
TSSOP TQFN
DIP/
SSOP/
TSSOP
SO/
SSOP/
TSSOP
THIN
QFN NAME
FUNCTION
— — — — — 19, 20 R_OUTB
Noninverting Complementary Receiver Outputs.
Always active.
— — — — —
9, 16,
25, 32 N.C. No Connection. Not internally connected.
EP — EP — — EP GND
Exposed Paddle. Solder the exposed paddle to the
ground plane or leave unconnected.
MAX3243E
I/O
CHIP
WITH
UART
CPU
RS-232
POWER-
MANAGEMENT
UNIT OR
KEYBOARD
CONTROLLER
FORCEOFF
FORCEON
INVALID
Figure 1. Interface Under Control of PMU
LapLink is a trademark of Traveling Software.
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
8 _______________________________________________________________________________________
RS-232 Receivers
The MAX3221E/MAX3223E/MAX3243E’s receivers con-
vert RS-232 signals to CMOS-logic output levels. All
receivers have inverting three-state outputs and can be
active or inactive. In shutdown (FORCEOFF = low) or in
AutoShutdown, the MAX3221E/MAX3223E’s receivers
are active (Table 1). Drive EN high to place the receiv-
er(s) in a high-impedance state. The MAX3243E’s
receivers are high-impedance when the part is in shut-
down (FORCEOFF = low).
The MAX3243E features an extra, always-active com-
plementary output (R2OUTB). R2OUTB 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
drops to 0 in shutdown to accommodate peripherals
such as UARTs (Figure 2).
The MAX3221E/MAX3223E/MAX3243E feature an
INVALID output that is enabled low when no valid RS-232
signal levels have been detected on all receiver inputs.
INVALID is functional in any mode (Figures 3 and 5).
AutoShutdown
The MAX3221E/MAX3223E/MAX3243E achieve a 1µA
supply current with Maxim’s new AutoShutdown fea-
ture, which operates when FORCEON is low and
FORCEOFF is high. When these devices sense no valid
signal levels on all receiver inputs for 30µs, the on-
board charge pump and drivers are shut off, reducing
supply current to 1µA. This occurs if the RS-232 cable
is disconnected or the connected peripheral transmit-
ters are turned off. The device 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.
Table 2 and Figure 3c summarize the MAX3221E/
MAX3223E/MAX3243E operating modes. FORCEON
and FORCEOFF override AutoShutdown. 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. Figure 5 shows the input levels and timing dia-
gram for AutoShutdown operation.
MAX3243E
T1OUT
R2OUTB
Tx
5kΩ
UART
VCC
T1IN
THREE-STATED
LOGIC
TRANSITION
DETECTOR
R2IN
PROTECTION
DIODE
R2OUT
FORCEOFF = GND
VCC
TO
μP
Rx
PREVIOUS
RS-232
Tx
UART
SHDN = GND
VCC
VCC
GND
Rx
5kΩ
a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE
RECEIVER OUTPUT IN SHUTDOWN.
b) NEW MAX3243E: IN SHUTDOWN, R2OUTB IS USED TO MONITOR EXTERNAL
DEVICES AND R2OUT IS THREE STATED, ELIMINATING A CURRENT PATH
THROUGH THE UART'S PROTECTION DIODE.
GND
PROTECTION
DIODE
I
I
Figure 2. The MAX3243E detects RS-232 activity when the
UART and interface are shut down.
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
_______________________________________________________________________________________ 9
Table 1. Output Control Truth Table
+0.3V
-0.3V
INVALID
TO MAX32_ _E
POWER SUPPLY
AND TRANSMITTERS
R_IN
* TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1μA IF
ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30μs.
30μs
COUNTER
R
Figure 3a. MAX32_ _E Entering 1µA Supply Mode via
AutoShutdown
+2.7V
-2.7V
INVALID
TO MAX32_ _E
POWER SUPPLY
R_IN
*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.
30μs
COUNTER
R
Figure 3b. MAX32_ _E with Transmitters Enabled Using
AutoShutdown
X = Don’t Care
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 MAX3221E/
MAX3223E/ MAX3243E are awake. If the other system
transmits valid RS-232 signals within that time, the RS-
232 ports on both systems remain enabled.
When shut down, the device’s charge pumps are off,
V+ is pulled to VCC, V- is pulled to ground, and the
transmitter outputs are high impedance. The time
required to exit shutdown is typically 100µs (Figure 5b).
Software-Controlled Shutdown
If direct software control is desired, INVALID can be
used to indicate DTR or Ring Indicator signal. Connect
FORCEOFF and FORCEON together to disable Auto-
Shutdown so the line acts like a SHDN input.
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures are
incorporated on all pins to protect against electrostatic
discharges encountered during handling and assembly.
The driver outputs and receiver inputs of the
MAX3221E/MAX3223E/MAX3243E have extra protection
against static electricity. Maxim’s engineers have devel-
oped state-of-the-art structures to protect these pins
against ESD of ±15kV without damage. The ESD struc-
tures withstand high ESD in all states: normal operation,
shutdown, and powered down. After an ESD event,
Maxim’s E versions keep working without latchup,
whereas competing RS-232 products can latch and
must be powered down to remove latchup. See Table 4.
0
0
0
1
X
1
FORCEON
X
Active
Active
Active
R2OUTB
(MAX3243E)
Active
Active
Active
Active
Active
Active
High-Z
R_OUT
(MAX3221E/
MAX3223E)
Active
Active
High-Z
High-Z
1
1
1
1
0
1
FORCEOFF
0
Active
High-Z
Active
T_OUT
High-Z
Active
Active
High-Z
Active
Active
Active
R_OUT
(MAX3243E)
High-Z
Active
Active
High-Z
0
0Yes
No
Normal Operation
(AutoShutdown) Yes
0 X
Normal Operation
(Forced On) X
Shutdown
(Forced Off) X
EN
(MAX3221E/
MAX3223E)
VALID
RECEIVER
LEVEL
0 X
OPERATION
STATUS
1
1
1
0ActiveHigh-Z1High-Z Active
Shutdown
(AutoShutdown) No1
MAX3221E/MAX3223E/MAX3243E
10 ______________________________________________________________________________________
ESD protection can be tested in various ways; the trans-
mitter outputs and receiver inputs of this product family
are characterized for protection to the following limits:
1) ±15kV using the Human Body Model
2) ±8kV using the Contact Discharge Method specified
in IEC1000-4-2
3) ±15kV using IEC1000-4-2’s Air-Gap Method
EESSDD TTeesstt CCoonnddiittiioonnss
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.
HHuummaann BBooddyy MMooddeell
Figure 6a shows the Human Body Model, and Figure
6b shows the current waveform it generates when dis-
charged into a low impedance. This model consists of a
100pF capacitor charged to the ESD voltage of interest,
which is then discharged into the test device through a
1.5kΩresistor.
IEC1000-4-2
The IEC1000-4-2 standard covers ESD testing and per-
formance of finished equipment; it does not specifically
refer to integrated circuits. The MAX3221E/ MAX3223E/
MAX3243E help you design equipment that meets
V-
VCC
0
V+
0
VCC
tINVL
tWU
INVALID
REGION
RECEIVER
INPUT
VOLTAGE
(V)
INVALID
OUTPUT
(V)
tINVH
TRANSMITTERS ENABLED, INVALID HIGH
RECEIVER INPUT LEVELS
AUTOSHUTDOWN, TRANSMITTERS DISABLED,
1μA SUPPLY CURRENT, INVALID LOW
TRANSMITTERS ENABLED, INVALID HIGH
-2.7V
-0.3V
+2.7V
+0.3V
0
INDETERMINATE
INDETERMINATE
b)
a)
Figure 5. AutoShutdown Trip Levels
FORCEON
MASTER SHDN LINE
0.1μF1MΩ
FORCEOFF
MAX3221E
MAX3223E
MAX3243E
POWER-
MANAGEMENT
UNIT
Figure 4. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System
FORCEOFF POWER DOWN
INVALID
FORCEON
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. MAX32_ _E AutoShutdown Logic
Table 2. INVALID Truth Table
LowNo
HighYes
INVALID OUTPUT
RS-232 SIGNAL PRESENT
AT ANY RECEIVER INPUT
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
______________________________________________________________________________________ 11
Level 4 (the highest level) of IEC1000-4-2, without the
need for additional ESD-protection components.
The major difference between tests done using the
Human Body Model and IEC1000-4-2 is higher peak
current in IEC1000-4-2, because series resistance is
lower in the IEC1000-4-2 model. Hence, the ESD with-
stand voltage measured to IEC1000-4-2 is generally
lower than that measured using the Human Body
Model. Figure 7a shows the IEEE1000-4-2 model and
Figure 7b shows the current waveform for the ±8kV
IEC1000-4-2 Level 4 ESD contact-discharge test.
The air-gap test involves approaching the device with a
charged probe. The contact-discharge method connects
the probe to the device before the probe is energized.
Machine Model
The Machine Model for ESD tests all pins using a 200pF
storage capacitor and zero discharge resistance. Its
objective is to emulate the stress caused by contact that
occurs with handling and assembly during manufactur-
ing. Of course, all pins require this protection during
manufacturing, not just RS-232 inputs and outputs.
Therefore, after PC board assembly, the Machine Model
is less relevant to I/O ports.
___________Applications Information
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).
CHARGE-CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
100pF
RC 1MΩRD 1500Ω
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
CHARGE CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
Cs
150pF
RC 50MΩ to 100MΩRD 330Ω
HIGH-
VOLTAGE
DC
SOURCE
DEVICE
UNDER
TEST
Figure 7a. IEC1000-4-2 ESD Test Model
tr = 0.7ns to 1ns
30ns
60ns
t
100%
90%
10%
IPEAK
I
Figure 7b. IEC1000-4-2 ESD Generator Current Waveform
Figure 6a. Human Body ESD Test Models
IP 100%
90%
36.8%
tRL TIME
tDL
CURRENT WAVEFORM
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
10%
0
0
AMPERES
Figure 6b. Human Body Model Current Waveform
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
12 ______________________________________________________________________________________
When using the minimum required capacitor values,
make sure the capacitor value does not degrade exces-
sively 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-.
Power-Supply Decoupling
In most circumstances, a 0.1µF VCC bypass capacitor is
adequate. In applications that are sensitive to power-
supply noise, use 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 8 shows two transmitter outputs when exiting
shut down mode. As they become active, the two trans-
mitter outputs are shown going to opposite RS-232 lev-
els (one transmitter output is high, the other is low).
Each transmitter is loaded with 3kΩin parallel with
1000pF. The transmitter outputs display no ringing or
undesirable transients as they come out of shutdown,
and are enabled only when the magnitude of V-
exceeds approximately -3V.
High Data Rates
The MAX3221E/MAX3223E/MAX3243E maintain the RS-
232 ±5.0V minimum transmitter output voltage even at
high data rates. Figure 9 shows a transmitter loopback
test circuit. Figure 10 shows a loopback test result at
120kbps, and Figure 11 shows the same test at 250kbps.
For Figure 10, all three transmitters were driven simulta-
neously at 120kbps into RS-232 loads in parallel with
1000pF. For Figure 11, a single transmitter was driven at
250kbps, and all three transmitters were loaded with an
RS-232 receiver in parallel with 1000pF.
Mouse Driveability (MAX3243E)
The MAX3243E has been specifically designed to power
serial mice while operating from low-voltage power sup-
plies. It has been tested with leading mouse brands such
as Logitech and Microsoft. When tested, the MAX3243E
successfully drove all serial mice and met their respective
current and voltage requirements. The MAX3243E’s regu-
lated dual charge pump ensures the transmitters will sup-
ply at least ±5V during worst-case conditions. Figure 12a
shows the transmitter outputs under increasing load cur-
rent. The AutoShutdown feature does not work with a
mouse, so FORCEOFF and FORCEON should be con-
nected to VCC. Figure 12b (on the following page) shows
a mouse driver test circuit. To achieve mouse driveability
with 1µA supply current when the port is inactive, use
parts with the AutoShutdown Plus™ feature (such as the
MAX3244E and MAX3245E).
0.330.0474.5 to 5.5
0.10.13.15 to 3.6
0.220.223.0 to 3.6
C2, C3, C4
(µF)
C1, CBYPASS
(µF)
VCC
(V)
Table 3. Required Capacitor Values
10.223.0 to 5.5
40μs/div
T2OUT
FORCEON =
FORCEOFF
T1OUT
5V/div
2V/div
VCC = 3.3V
C1–C4 = 0.1μF
Figure 8. Transmitter Outputs Exiting Shutdown or Powering Up
AutoShutdown Plus is a trademark of Maxim Integrated Products, Inc.
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
______________________________________________________________________________________ 13
Figure 9. Loopback Test Circuit
MAX3221E
MAX3223E
MAX3243E
5kΩ
R_ IN
R_ OUT
EN (MAX3221E/3E)
C2-
C2+
C1-
C1+
V-
V+
VCC
C4
C3
C1
C2
0.1μF
VCC
FORCEOFF
T_ OUT
T_ IN
GND
VCC
0
1000pF
2μs/div
T1IN
T1OUT
R1OUT
5V/div
5V/div
5V/div
VCC = 3.3V
Figure 10. Loopback Test Result at 120kbps
Table 4. ±15kV ESD-Protected, 3.0V to 5.5V Powered RS-232 Transceivers from Maxim
PART
SUPPLY
VOLTAGE
RANGE
(V)
NO.
OF
Tx/Rx
GUARANTEED
DATA RATE
(kbps)
SUPPLY
CURRENT
(µA)
MAX3241E +3.0 to +5.5 3/5 250300
MAX3243E +3.0 to +5.5 3/5 2501
MAX3244E +3.0 to +5.5 3/5 2501
MAX3245E +3.0 to +5.5 3/5 1Mbps1
MAX3232E +3.0 to +5.5 2/2 250300
MAX3222E +3.0 to +5.5 2/2 250300
MAX3223E +3.0 to +5.5 2/2 2501
MAX3224E +3.0 to +5.5 2/2 2501
MAX3225E +3.0 to +5.5 2/2 1Mbps1
MAX3221E +3.0 to +5.5 1/1 2501
MAX3227E +3.0 to +5.5 1/1 1Mbps1
MAX3226E +3.0 to +5.5 1/1 2501
Auto-
Shutdown
Plus
—
—
Yes
Yes
—
—
—
Yes
Yes
—
Yes
Yes
Auto-
Shutdown
—
Yes
—
—
—
—
Yes
—
—
Yes
—
—
HUMAN
BODY
MODEL
(kV)
±15
±15
±15
±15
±15
±15
±15
±15
±15
±15
±15
±15
IEC 1000-4-2
CONTACT
DISCHARGE
(kV)
±8
±8
±8
±8
±8
±8
±8
±8
±8
±8
±8
±8
IEC 1000-4-2
AIR-GAP
DISCHARGE
(kV)
±15
±15
±15
±15
±15
±15
±15
±15
±15
±15
±15
±15
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
14 ______________________________________________________________________________________
Figure 11. Loopback Test Result at 250kbps
2μs/div
T1IN
T1OUT
R1OUT
5V/div
5V/div
5V/div
VCC = 3.3V
Compatible with ACT and
HCT CMOS, and with TTL.
Incompatible with AC, HC,
or CD4000 CMOS.
3.35
SYSTEM
POWER-
SUPPLY
VOLTAGE
(V)
Compatible with all TTL and
CMOS-logic families.
55
Compatible with all CMOS
families.
3.33.3
COMPATIBILITY
VCC SUPPLY
VOLTAGE
(V)
Table 5. Logic Family Compatibility with
Various Supply Voltages
Figure 12a. Transmitter Output Voltage vs. Load Current per
Transmitter
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
012345678910
MAX2343E-FIG15
LOAD CURRENT PER TRANSMITTER (mA)
TRANSMITTER OUTPUT VOLTAGE (V)
VOUT+
VOUT-
VOUT+
VOUT-
VCC
VCC = 3.0V
___________________Chip Information
MAX3221E TRANSISTOR COUNT: 269
MAX3223E TRANSISTOR COUNT: 339
MAX3243E TRANSISTOR COUNT: 476
PROCESS: BiCMOS
PART TEMP
RANGE
PIN-
PACKAGE
MAX3243ECWI 0°C to +70°C28 Wide SO
MAX3243ECAI 0°C to +70°C28 SSOP
MAX3243EEWI -40°C to +85°C28 Wide SO
MAX3243EEAI -40°C to +85°C28 SSOP
MAX3243ECUI 0°C to +70°C28 TSSOP
MAX3243EEUI -40°C to +85°C28 TSSOP
MAX3243ECTJ 0°C to +70°C32 Thin QFN-EP
(7mm x 7mm)*
MAX3243EETJ -40°C to +85°C32 Thin QFN-EP
(7mm x 7mm)*
PKG
CODE
—
—
—
—
—
—
T3277-2
T3277-2
Ordering Information (continued)
Interconnection with 3V and 5V Logic
The MAX3221E/MAX3223E/MAX3243E can directly
interface with various 5V logic families, including ACT
and xHCT CMOS. See Table 5 for more information on
possible combinations of interconnections.
*
Exposed paddle.
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
______________________________________________________________________________________ 15
+V
COMPUTER SERIAL PORT
+V
-V
GND
Tx
SERIAL
MOUSE
MAX3243E
FORCEOFF
23
R5OUT
15
R4OUT
16
R3OUT
17
R2OUT
18
R1OUT
19
R2OUTB
20
LOGIC
OUTPUTS
5kΩ
5kΩ
5kΩ
5kΩ
5kΩ
R5IN 8
R4IN 7
R3IN 6
R2IN 5
R1IN 4
RS-232
INPUTS
GND
25
LOGIC
INPUTS
T3IN
12
T2IN
13
T1IN
14
C2-
2
C2+
1
C1-
24
C1+
28
T3OUT 11
T2OUT 10
T1OUT 9
V-
3
V+
27
VCC
VCC
VCC
C4
0.1μF
C3
0.1μF
0.1μF 26
C1
0.1μF
C2
0.1μF
FORCEON
INVALID
22
21
TO POWER-
MANAGEMENT
UNIT
+3.3V
Figure 12b. Mouse Driver Test Circuit
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
16 ______________________________________________________________________________________
Typical Operating Circuits
MAX3223E**
FORCEON
EN
14
1
R2OUT10
R1OUT15
FORCEOFF 20
INVALID 11
R2IN 9
GND
18
RS-232
OUTPUTS
TTL/CMOS
INPUTS T2IN
12
T1IN
13
C2-
6
C2+
5
C1-
4
C1+
2
R1IN 16
T2OUT 8
T1OUT 17
V- 7
V+ 3
VCC
VCC
C4
0.1μF
C3
0.1μF
0.1μF 19
C1
0.1μF
C2
0.1μF
CBYPASS
+3.3V
RS-232
INPUTS
TO POWER-
MANAGEMENT
UNIT
TTL/CMOS
OUTPUTS 5kΩ
5kΩ
MAX3243E
FORCEOFF
23
R5OUT
15
R4OUT
16
R3OUT
17
R2OUT
18
R1OUT
19
R2OUTB
20
LOGIC
OUTPUTS
5kΩ
5kΩ
5kΩ
5kΩ
5kΩ
R5IN 8
R4IN 7
R3IN 6
R2IN 5
R1IN 4
RS-232
INPUTS
GND
25
RS-232
OUTPUTS
LOGIC
INPUTS
T3IN
12
T2IN
13
T1IN
14
C2-
2
C2+
1
C1-
24
C1+
28
T3OUT 11
T2OUT 10
T1OUT 9
V- 3
V+ 27
VCC
CBYPASS
VCC
C4
0.1μF
C3
0.1μF
0.1μF 26
C1
0.1μF
C2
0.1μF
FORCEON
INVALID
22
21
TO POWER-
MANAGEMENT UNIT
+3.3V
MAX3221E*
FORCEON
EN
12
1
R1OUT9
FORCEOFF 16
INVALID 10
GND
14
T1IN
11
C2-
6
C2+
5
C1-
4
C1+
2
R1IN 8
T1OUT 13
V- 7
V+ 3
VCC
VCC
C4
0.1μF
C3
0.1μF
0.1μF 15
C1
0.1μF
C2
0.1μF
CBYPASS
+3.3V
TO POWER-
MANAGEMENT
UNIT
5kΩ
*MAX3221E PIN OUT REFERS TO SSOP/TSSOP PACKAGES.
**MAX3223E PIN OUT REFERS TO DIP/SSOP/TSSOP PACKAGES.
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
______________________________________________________________________________________ 17
Pin Configurations
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
FORCEOFF
VCC
GND
T1OUT
C1-
V+
C1+
EN
R1IN
R1OUT
FORCEON
T1IN
T2OUT
V-
C2-
C2+
12
11
9
10
T2IN
INVALID
R2OUT
R2IN
DIP/SSOP/TSSOP
MAX3223E
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
C1+
V+
VCC
GND
C1-
FORCEON
FORCEOFF
INVALID
R2OUTB
R1OUT
R2OUT
R3OUT
R4OUT
R5OUT
C2+
C2-
V-
R1IN
R2IN
R3IN
R4IN
R5IN
T1OUT
T2OUT
T3OUT
T3IN
T2IN
T1IN
SO/SSOP/TSSOP
MAX3243E
TOP VIEW
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
EN
C1+
V+
C1-
C2+
C2-
V-
R1IN
FORCEOFF
VCC
GND
T1OUT
FORCEON
T1IN
INVALID
R1OUT
MAX3221E
SSOP/TSSOP
TQFN
32
31
30
29
28
27
26
N.C.
V-
C2-
C2+
C1+
V+
VCC
25
N.C.
9
10
11
12
13
14
15
N.C.
T3IN
T2IN
T1IN
R5OUT
R4OUT
R3OUT
16 N.C.
17181920212223
R2OUT
R1OUT
R2OUTB
R1OUTB
SHDN
EN
C1-
8765432
T3OUT
T2OUT
T1OUT
R5IN
R4IN
R3IN
R2IN
MAX3243E
1
R1IN
24
GND
TOP VIEW
MAX3221E/MAX3223E/MAX3243E
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
RS-232 Transceivers with AutoShutdown
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
18
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
Pin Configurations (continued)
15
16
14
13
6
5
7
C2+
V-
8
C1-
GND
FORCEON
VCC
12
EN
4
12 11 9
V+
C1+
* EP = EXPOSED PADDLE
T1IN
INVALID
R1OUT
R1IN
MAX3221E*
C2- T1OUT
3
10
FORCEOFF
TQFN
TOP VIEW
MAX3223E*
TQFN
19
20
18
17
7
6
8
C1-
C2-
V-
9
C1+
R1IN
FORCEON
T1IN
T1OUT
12
FORCEOFF
45
15 14 12 11
EN
V+
* EP = EXPOSED PADDLE
INVALID
R2OUT
R2IN
T2OUT
C2+ R1OUT
3
13
VCC
16 10 T2IN
GND
