FREI MAX 3223 CPP Datasheet

_______________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
on-board 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. As a result, the system
saves power without changes to the existing BIOS or
operating system.

The MAX3221/MAX3223/MAX3243 transceivers are 3V­powered EIA/TIA-232 and V.28/V.24 communications
interfaces intended for notebook computer applica­tions. 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. A guaranteed data rate of 120kbps pro­vides compatibility with popular software for communi­cating with personal computers.

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. They are ideal for

3.3V-only systems, mixed 3.3V and 5.0V systems, or

5.0V-only systems that require true RS-232 performance.
The MAX3221 is a 1-driver/1-receiver 16-pin SSOP ver-

sion of the 20-pin MAX3223 (2-driver/2-receiver). The
MAX3243 3-driver/5-receiver, complete serial port is
ideal for notebook or subnotebook computers. The
MAX3243 includes one complementary always-active
receiver. This receiver can monitor an external device
(such as a modem) in shutdown, without forward bias­ing the protection diodes in a UART that may have V

CC

completely removed.

Next Generation Device Features

♦ For Space-Constrained Applications:

MAX3228/MAX3229: +2.5V to +5.5V RS-232
Transceivers in UCSP™

♦ For Integrated ESD Protection:

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 UCSP
Package)

♦ For Low-Voltage or Data Cable Applications:

MAX3380E/MAX3381E: +2.5V to +5.5V, 1µA,
2 Tx/2 Rx RS-232 Transceivers with ±15kV ESD­Protected I/O and Logic Pins

________________________Applications

Notebook, Subnotebook, and Palmtop Computers
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Printers

MAX3221/MAX3223/MAX3243*

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

________________________________________________________________ Maxim Integrated Products 1

19-0306; Rev 8; 10/03

PART

MAX3221CAE

MAX3221EUE†

-40°C to +85°C

0°C to +70°C

TEMP RANGE PIN-PACKAGE

16 SSOP

16 TSSOP

* Covered by U.S. Patent numbers 4,636,930; 4,679,134; 4,777,577; 4,797,899; 4,809,152; 4,897,774; 4,999,761; and other patents pending.

†Future product—contact factory for availability.
AutoShutdown and UCSP are trademarks of Maxim Integrated
Products, Inc.

Pin Configurations appear at end of data sheet.
Typical Operating Circuits appear at end of data sheet.

MAX3223EPP -40°C to +85°C 20 Plastic DIP
MAX3223EAP -40°C to +85°C 20 SSOP

MAX3243CWI

0°C to +70°C 28 Wide SO

MAX3243CAI 0°C to +70°C 28 SSOP

MAX3243EWI -40°C to +85°C 28 Wide SO
MAX3243EAI -40°C to +85°C 28 SSOP

MAX3223CPP
MAX3223CAP 0°C to +70°C

0°C to +70°C 20 Plastic DIP

20 SSOP

______________Ordering Information

_____________________Selector Guide

MAX3221
MAX3223
MAX3243

1
2
3

1
2

3.0 to 5.5

3.0 to 5.5

3.0 to 5.55

Yes
Yes
Yes

PART Tx Rx VCCRANGE (V) AutoShutdown

MAX3221CUE†

0°C to +70°C 16 TSSOP

MAX3221EAE -40°C to +85°C 16 SSOP

MAX3223CUP 0°C to +70°C 20 TSSOP

MAX3223EUP -40°C to +85°C 20 TSSOP

MAX3243CUI 0°C to +70°C 28 TSSOP

MAX3243EUI -40°C to +85°C 28 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.

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA= T

MIN

to T

MAX

, 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...........................................................................-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 (V

CC

+ 0.3V)

Short-Circuit Duration

T_OUT ......................................................................Continuous

Continuous Power Dissipation (T

A

= +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.

I

OUT

= 1.6mA

Receivers disabled

T_IN, EN, FORCEON, FORCEOFF

T_IN, EN, FORCEON, FORCEOFF

T_IN, FORCEON, FORCEOFF, EN (MAX3223)

I

OUT

= -1.0mA

CONDITIONS

VVCC- 0.6 VCC- 0.1Output Voltage High

V0.4Output Voltage Low

µA±0.05 ±10Output Leakage Current

µA±0.01 ±1.0Input Leakage Current

V

2.4

Input Logic Threshold High

µA1.0 10

V0.8Input Logic Threshold Low

UNITSMIN TYP MAXPARAMETER

VCC= 3.3V
VCC= 5.0V

2.0

Supply Current, AutoShutdown

Supply Current, Shutdown µA1.0 10
Supply Current,

AutoShutdown Disabled

VCC= 3.3V
or 5.0V,
TA= +25°C

mA0.3 1.0

2.7

Receiver Positive or Negative
Threshold to INVALID High (t

INVH

)

Figure 5 µs1

Receiver Threshold to
Transmitters Enabled (tWU)

Figure 5 µs250

Receiver Positive or Negative
Threshold to INVALID Low (t

INVL

)

Figure 5 µs30

Receiver Input Thresholds to
Transmitters Enabled

Figure 5 V

-2.7

INVALID Output Voltage Low

I

OUT

= 1.6mA V0.4

Receiver Input Thresholds to
Transmitters Disabled

1µA supply current, Figure 5 V-0.3 0.3

Positive threshold
Negative threshold

INVALID Output Voltage High

I

OUT

= -1.0mA VVCC- 0.6

DC CHARACTERISTICS

LOGIC INPUTS AND RECEIVER OUTPUTS

AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC)

All R_IN open, FORCEON = GND,
FORCEOFF = V

CC

FORCEOFF = GND
FORCEON = FORCEOFF = VCC,

no load

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA= T

MIN

to T

MAX

, 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%.

200

Normal operation 200

Receiver Output Enable Time Normal operation ns

t

PLH

Receiver input to receiver output,
C

L

= 150pF

4 8.0 30

Transition-Region Slew Rate V/µs

VCC= 3.3V,
R

L

= 3kΩ to 7kΩ,
TA= +25°C,
measured from +3V to

-3V or -3V to +3V

Transmitter Skew

200

ns



t

PHL

- t

PLH



PARAMETER MIN TYP MAX UNITS

±25

Output Short-Circuit Current ±35 ±60 mA

Output Resistance 300 10M Ω

Output Leakage Current µA

Input Threshold Low

0.6 1.2
V

±5.0 ±5.4Output Voltage Swing V

Maximum Data Rate 120 235 kbps

Receiver Propagation Delay

0.3

µs

CONDITIONS

VCC= V+ = V- = 0V, transmitter output = ±2V

V

OUT

= ±12V, VCC= 0V or 3.0V to 5.5V,

transmitters disabled

RL= 3kΩ, CL= 1000pF, one transmitter switching

All transmitter outputs loaded with 3kΩ to ground

nsReceiver Output Disable Time

t

PHL

0.3

Input Voltage Range -25 25 V

Input Hysteresis 0.3 V

Input Threshold High V

Input Resistance 35 7kΩTA= +25°C

0.8 1.5

1.8 2.4

1.5 2.4

TA= +25°C

TA= +25°C

VCC= 3.3V

VCC= 3.3V

VCC= 5.0V

VCC= 5.0V

CL= 200pF to 2500pF

CL= 200pF to 1000pF 630

±5Transmitter Output Voltage V

T1IN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩ to GND, T1OUT and
T2OUT loaded with 2.5mA each

MAX3221/MAX3223
MAX3243

200 1000

Receiver Skew

100

ns



t

PHL

- t

PLH



MAX3221/MAX3223
MAX3243

100 500

RECEIVER INPUTS

TIMING CHARACTERISTICS

TRANSMITTER OUTPUTS

MOUSE DRIVEABILITY (MAX3243)

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

4 _______________________________________________________________________________________

__________________________________________Typical Operating Characteristics

(VCC= +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, TA= +25°C, unless otherwise noted.)

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

0

MAX3221/MAX3223

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3221/3223-01

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

2000 30001000 4000 5000

V

OUT+

V

OUT-

0

2

4

6

8

10

12

14

16

18

20

22

150 500

MAX3221/MAX3223

SLEW RATE

vs. LOAD CAPACITANCE

MAX3221/3223-02

LOAD CAPACITANCE (pF)

SLEW RATE (V/µs)

2000 30001000 4000 5000

FOR DATA RATES UP TO 235kbps

+SLEW

-SLEW

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

0

MAX3221/MAX3223

SUPPLY CURRENT vs. LOAD CAPACITANCE

WHEN TRANSMITTING DATA

MAX3221/3223-03

LOAD CAPACITANCE (pF)

MAX3223 SUPPLY CURRENT (mA)

MAX3221 SUPPLY CURRENT (mA)

2000 30001000 4000 5000

235kbps

120kbps

20kbps

-7.5

-5.0

-2.5

0

2.5

5.0

7.5

0

MAX3243

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3221/3223-04

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

2000 30001000 4000 5000

V

OUT

+

1 TRANSMITTER AT 235kbps
2 TRANSMITTERS AT 30kbps

V

OUT

-

ALL OUTPUTS LOADED WITH 3kΩ +CL

0.1µF CHARGE-PUMP CAPACITORS
FOR ALL DATA RATES UP TO 235kbps

4

6

8

10

12

14

16

18

20

22

24

0

MAX3243

SLEW RATE

vs. LOAD CAPACITANCE

MAX3221/3223-05

LOAD CAPACITANCE (pF)

SLEW RATE (V/µs)

2000 30001000 4000 5000

+SLEW

-SLEW

0

5

10

15

20

25

30

35

45
40

0

MAX3243

SUPPLY CURRENT vs. LOAD

CAPACITANCE WHEN TRANSMITTING DATA

MAX3221/3223-06

LOAD CAPACITANCE (pF)

SUPPLY CURRENT (mA)

2000 30001000 4000 5000

235kbps

120kbps

20kbps

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

_______________________________________________________________________________________ 5

______________________________________________________________Pin Description

Noninverting Receiver Output—active in shutdownR2OUTB
Output of the valid signal detector. Indicates if a valid RS-232 level is pres-

ent on receiver inputs logic “1”.

INVALID

Drive low to shut down transmitters and on-board power supply. This over­rides all automatic circuitry and FORCEON (Table 1).

FORCEOFF

Drive high to override automatic circuitry keeping transmitters on
(FORCEOFF must be high) (Table 1).

FORCEON

Negative terminal of the voltage doubler charge-pump capacitorC1-

RS-232 Receiver InputsR_IN
RS-232 Transmitter OutputsT_OUT
TTL/CMOS Transmitter InputsT_IN
TTL/CMOS Receiver OutputsR_OUT

-5.5V generated by the charge pumpV-

Negative terminal of inverting charge-pump capacitorC2-

Positive terminal of inverting charge-pump capacitorC2+

Receiver Enable Control. Drive low for normal operation. Drive high to force
the receiver outputs into a high-Z state.

EN

FUNCTION

GroundGND
+3.0V to +5.5V Supply VoltageV

CC

LapLink is a trademark of Traveling Software.

_______________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 Auto­Shutdown circuitry senses invalid voltage levels at all
receiver inputs, the transmitters are disabled and the
outputs are forced into a high-impedance state.

—

10

16

12

4

8
13
11

9

7

6

5

1

14
15

NAME

MAX3221

+5.5V generated by the charge pumpV+3
Positive terminal of the voltage doubler charge-pump capacitorC1+2

—

11

20

14

4

9, 16

8, 17
12, 13
10, 15

7

6

5

1

18
19

20

21

22

23

24

4–8

9, 10, 11

12, 13, 14

15–19

3

2

1

—

25
26

MAX32233MAX3243

27

2 28

PIN

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

6 _______________________________________________________________________________________

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 VCCis
set to 0V in shutdown to accommodate peripherals,
such as UARTs (Figure 2).

MAX3243

I/O

CHIP
WITH
UART

CPU

RS-232

POWER
MANAGEMENT
UNIT OR
KEYBOARD
CONTROLLER

FORCEOFF
FORCEON

INVALID

MAX3243

T1OUT

R2OUTB

Tx

5kΩ

UART

V

CC

T1IN

THREE-STATED

LOGIC

TRANSITION

DETECTOR

R2IN

PROTECTION
DIODE

R2OUT

FORCEOFF = GND

V

CC

TO
µP

Rx

PREVIOUS

RS-232

Tx

UART

SHDN = GND

V

CC

V

CC

GND

Rx

5kΩ

(a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE

RECEIVER OUTPUT IN SHUTDOWN.

(b) 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.

GND

PROTECTION
DIODE

I

I

Figure 1. Interface Under Control of PMU

Figure 2. The MAX3243 detects RS-232 activity when the
UART and interface are shut down.

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

_______________________________________________________________________________________ 7

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
low-power 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

Table 1a. MAX3221/MAX3223 FFOORRCCEEOOFFFF and

Enable Control Truth Table

Table 1b. MAX3243 FFOORRCCEEOOFFFF Control
Truth Table

Active*11

Active*01

FFOORRCCEEOOFFFF

High-Z10

High-Z00

T_OUT

EENN

High-Z

Active

High-Z

Active

R_OUT

Active*1

High-Z0

T_OUT

FFOORRCCEEOOFFFF

Active*

High-Z

R_OUT

Active

Active

R2OUTB

Figure 3a. MAX32_ _ Entering 1µA Supply Mode via
AutoShutdown

*Note: If the part is in AutoShutdown mode (FORCEOFF = V

CC

,
FORCEON = GND), it is shut down if no valid RS-232
levels are present on all receiver inputs.

FORCEON

MASTER SHDN LINE

0.1µF1MΩ

FORCEOFF

MAX3221
MAX3223
MAX3243

POWER

MANAGEMENT

UNIT

Figure 4. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System

+2.7V

-2.7V

INVALID

TO MAX32_ _

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_ _ with Transmitters Enabled Using
AutoShutdown

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. AutoShutdown Logic

+0.3V

R_IN

-0.3V

* 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

TO MAX32_ _

POWER SUPPLY

AND TRANSMITTERS

INVALID

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

8 _______________________________________________________________________________________

other system to realize that the MAX3221/MAX3223/
MAX3243 is awake. If the other system outputs 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 turned
off, V+ decays to V

CC

, V- decays to ground, and the
transmitter outputs are disabled (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. Tie
FORCEOFF and FORCEON together to bypass Auto­Shutdown so the line acts like a SHDN input.

___________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).

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-.

Table 2. AutoShutdown Logic

RS-232 SIGNAL

PRESENT AT

RECEIVER INPUT

FFOORRCCEEOOFFFF INPUT

FORCEON

INPUT

IINNVVAALLIIDD OUTPUT

TRANSCEIVER STATUS

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)

(b)

(a)

Figure 5. AutoShutdown Trip Levels

TRANSMITTERS ENABLED, INVALID HIGH

+2.7V

+0.3V

-0.3V

RECEIVER INPUT LEVELS

-2.7V

AUTOSHUTDOWN, TRANSMITTERS DISABLED,

0V

1µA SUPPLY CURRENT, INVALID LOW

TRANSMITTERS ENABLED, INVALID HIGH

INDETERMINATE

INDETERMINATE

RECEIVER

INPUT

VOLTAGE

(V)

V

CC

INVALID
OUTPUT

(V)

0

V+

V

CC

0

V-

t

INVL

t

INVH

INVALID
REGION

t

WU

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

_______________________________________________________________________________________ 9

Power-Supply Decoupling

In most circumstances a 0.1µF bypass capacitor is
adequate. In applications that are sensitive to power­supply noise, decouple VCCto 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 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 V

CC

.

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 driv­en 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.

-6

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

01234567

MAX3222-04

LOAD CURRENT PER TRANSMITTER (mA)

TRANSMITTER OUTPUT VOLTAGE (V)

V

OUT

+

VCC = 3.0V

V

OUT

-

V

OUT

+

V

CC

V

OUT

-

T

1

T

2

T

3

Figure 7a. MAX3243 Transmitter Output Voltage vs. Load
Current per Transmitter

5V/div

V

CC

= +3.3V

C1–C4 = 0.1µF

2V/div

T2

50µs/div

T1

Figure 6. Transmitter Outputs when Exiting Shutdown or
Powering Up

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

10 ______________________________________________________________________________________

+V

COMPUTER SERIAL PORT

+V

-V

GND

Tx

SERIAL

MOUSE

MAX3243

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

V

CC

V

CC

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 7b. Mouse Driver Test Circuit

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

______________________________________________________________________________________ 11

Figure 10. Loopback Test Result at 235kbps

T1IN

R1OUT

V

CC

= +3.3V, 235kbps

C1–C4 = 0.1µF

T1OUT

5V/div

5V/div

2µs/div

5V/div

Figure 8. Loopback Test Circuit

Figure 9. Loopback Test Result at 120kbps

T1IN

R1OUT

V

CC

= +3.3V, 120kbps

C1–C4 = 0.1µF

T1OUT

5V/div

5V/div

5V/div

5µs/div

Table 4. Logic Family Compatibility with
Various Supply Voltages

Table 3. Required Capacitor Values

VCCSUPPLY

VOLTAGE

(V)

COMPATIBILITY

3.3 3.3

Compatible with all CMOS
families.

5 5

Compatible with all TTL and
CMOS-logic families.

SYSTEM
POWER­SUPPLY

VOLTAGE

(V)

5 3.3

Compatible with ACT and
HCT CMOS, and with TTL.
Incompatible with AC, HC,
or CD4000 CMOS.

V

CC

(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

V

CC

0.1µF

C1+

C1

C2

0V

V

CC

C1-

C2+

C2-

T_ IN

R_ OUT

EN (MAX3221/3)

FORCEOFF

V

CC

MAX3221
MAX3223
MAX3243

GND

V+

T_ OUT

R_ IN

5kΩ

C3

V-

C4

1000pF

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

12 ______________________________________________________________________________________

__________________________________________________Typical Operating Circuits

MAX3243

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

V

CC

V

CC

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

+3.3V

15

V

CC

MAX3221

V+

V-

T1OUT 13

3

C3

0.1µF

7

C4

0.1µF

0.1µF

0.1µF

C1

C2

0.1µF

C5

2

C1+

4

C1-

5

C2+

6

C2-

11

T1IN

R1OUT9

1

12

2

4

5

6

1

EN

FORCEON

C1+

C1-

C2+

C2-

T1IN

T2IN

R1OUT15

R2OUT10

EN

FORCEON

GND

19

V

CC

MAX3223

GND

18

14

TTL/CMOS

TTL/CMOS

OUTPUTS

C5

C1

0.1µF

C2

0.1µF

INPUTS

+3.3V

0.1µF

13

12

14

5kΩ

INVALID 10

FORCEOFF

T1OUT 17

T2OUT

5kΩ

5kΩ

INVALID 11

FORCEOFF

R1IN 8

V+

V-

R1IN

R2IN

16

3

7

8

16

9

20

TO POWER
MANAGEMENT
UNIT

V

CC

C3

0.1µF

C4

0.1µF

RS-232
OUTPUTS

RS-232
INPUTS

TO POWER
MANAGEMENT
UNIT

V

CC

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

______________________________________________________________________________________ 13

______3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim

0.1µF capacitors, MAX242 pinout23212022/23.0 to 5.5MAX3222

0.1µF capacitors, AutoShutdown23212022/23.0 to 5.5MAX3223

0.1µF capacitors, AutoShutdown
complementary receiver,
drives mice

23212013/53.0 to 5.5MAX3243

0.1µF capacitors, MAX232 pinout232120N/A2/23.0 to 5.5MAX3232

0.1µF capacitors, 16-pin SSOP23212011/13.0 to 5.5MAX3221

232

562

232

562

232

EIA/TIA-

232

OR 562

2.7 to 3.6

AutoShutdown, complementary
receiver, drives mice, transient
detection

23553/5MAX3212

0.1µF capacitors12022/23.0 to 3.6MAX563

Operates directly from batteries
without a voltage regulator

12022/21.8 to 4.25MAX218

No. OF

RECEIVERS

ACTIVE IN

SHUTDOWN

POWER­SUPPLY

VOLTAGE

(V)

230kbps guaranteed data rate23053/52.7 to 5.25MAX562

Drives mice12053/53.0 to 3.6MAX212

FEATURES

GUAR-

ANTEED

DATA

RATE

(kbps)

No. OF

TRANSMITTERS/

RECEIVERS

PART

0.1µF capacitors, 2 complemen­tary receivers, drives mice

23212053/53.0 to 5.5MAX3241

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

14 ______________________________________________________________________________________

__________________________________________________________Pin Configurations

20

19

18

17

16

15

14

13

1

2

3

4

5

6

7

8

FORCEOFF

V

CC

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

MAX3223

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

V

CC

GND

T1OUT

FORCEON

T1IN

INVALID

R1OUT

MAX3221

SSOP/TSSOP

___________________Chip Information

MAX3221 TRANSISTOR COUNT: 269

MAX3223 TRANSISTOR COUNT: 339

MAX3243 TRANSISTOR COUNT: 476

C2+

1

C2-

2

V-

3

R1IN

4

R2IN

5

R3IN

R4IN

R5IN

T1OUT

T2OUT

T3OUT

T3IN

T2IN

T1IN

MAX3243

6

7

8

9

10

11

12

13

14

SO/SSOP/TSSOP

C1+

28

V+

27

V

26

CC

GND

25

C1-

24

FORCEON

23

FORCEOFF

22

INVALID

21

R2OUTB

R1OUT

R2OUT

R3OUT

R4OUT

R5OUT

20

19

18

17

16

15

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

______________________________________________________________________________________ 15

SSOP.EPS

PACKAGE OUTLINE, SSOP, 5.3 MM

1

1

21-0056

C

REV.DOCUMENT CONTROL NO.APPROVAL

PROPRIETARY INFORMATION

TITLE:

NOTES:

1. D&E DO NOT INCLUDE MOLD FLASH.

2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006").

3. CONTROLLING DIMENSION: MILLIMETERS.

4. MEETS JEDEC MO150.

5. LEADS TO BE COPLANAR WITHIN 0.10 MM.

7.90

H

L

0∞

0.301

0.025

8∞

0.311

0.037

0∞

7.65

0.63

8∞

0.95

MAX

5.38

MILLIMETERS

B

C

D

E

e

A1

DIM

A

SEE VARIATIONS

0.0256 BSC

0.010

0.004

0.205

0.002

0.015

0.008

0.212

0.008

INCHES

MIN

MAX

0.078

0.65 BSC

0.25

0.09

5.20

0.05

0.38

0.20

0.21

MIN

1.73 1.99

MILLIMETERS

6.07

6.07

10.07

8.07

7.07

INCHES

D
D

D

D

D

0.239

0.239

0.397

0.317

0.278

MIN

0.249

0.249

0.407

0.328

0.289

MAX

MIN

6.33

6.33

10.33

8.33

7.33

14L
16L

28L

24L

20L

MAX

N

A

D

e

A1

L

C

HE

N

12

B

0.068

TSSOP4.40mm.EPS

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

MAX3221/MAX3223/MAX3243

1µA Supply-Current, True +3V to +5.5V
RS-232 Transceivers with AutoShutdown

SOICW.EPS

PACKAGE OUTLINE, .300" SOIC

1

1

21-0042

B

REV.DOCUMENT CONTROL NO.APPROVAL

PROPRIETARY INFORMATION

TITLE:

TOP VIEW

FRONT VIEW

MAX

0.012

0.104

0.019

0.299

0.013

INCHES

0.291

0.009

E

C

DIM

0.014

0.004

B

A1

MIN

0.093A

0.23

7.40 7.60

0.32

MILLIMETERS

0.10

0.35

2.35

MIN

0.49

0.30

MAX

2.65

0.050

0.016L

0.40 1.27

0.5120.496D

D

MINDIM

D

INCHES

MAX

12.60 13.00

MILLIMETERS

MIN

MAX

20 AC

0.447 0.463 AB11.7511.35 18

0.398 0.413 AA10.5010.10 16

N MS013

SIDE VIEW

H 0.4190.394 10.00 10.65

e 0.050 1.27

D 0.6140.598 15.20 2415.60 AD
D 0.7130.697 17.70 2818.10 AE

H

E

N

D

A1

B

e

A

0∞-8∞

C

L

1

VARIATIONS:

PDIPN.EPS

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.

16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)