MAXIM MAX3221E, MAX3223E, MAX3243E User Guide

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 datarate capabilities, and enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to ±15kV using IEC 1000-4-2 AirGap 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 entering 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 transmitter 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 capacitors for operation from a +3.3V supply. Each device is guaranteed to run at data rates of 250kbps while maintaining 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 available in space-saving TQFN, SSOP, and TSSOP packages.

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 ESDProtected 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

PINPACKAGE

16 TSSOP

16 SSOP

AutoShutdown and UCSP are trademarks of Maxim Integrated Products, Inc.

†

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; 5,649,210; and other patents pending.

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°C

20 Plastic DIP

MAX3223EEAP

-40°C to +85°C

20 SSOP

MAX3221EETE

MAX3223ECAP

0°C to +70°C

-40°C to +85°C

16 Thin QFN-EP (5mm x 5mm)

20 SSOP

Ordering Information

Selector Guide

MAX3223ECUP

0°C to +70°C

20 TSSOP

MAX3223EEUP

-40°C to +85°C

20 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°C

16 SSOP —

MAX3221ECTE

0°C to +70°C

16 Thin QFN-EP (5mm x 5mm)

T1655-2

MAX3221EEUE

-40°C to +85°C

16 TSSOP —

MAX3223ECPP

0°C to +70°C

20 Plastic DIP —

MAX3223ECTP

0°C to +70°C

20 Thin QFN-EP* (5mm x 5mm)

T2055-5

MAX3223EETP

-40°C to +85°C

20 Thin QFN-EP* (5mm x 5mm)

T2055-5

PART

NO. OF

DRIVERS/

VCC

(V)

AutoShutdown

MAX3221E 1/1

✔

MAX3223E 2/2

✔

MAX3243E 3/5

✔

RANGE

RECEIVERS

+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= 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.

VCCto 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 (V

+ 0.3V)

Short-Circuit Duration

T_OUT to GND .........................................................Continuous

Continuous Power Dissipation (T

= +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

OUT

= -1.0mA

OUT

= 1.6mA

Figure 5a

OUT

= -1.0mA

OUT

= 1.6mA

T_IN, EN, FORCEON, FORCEOFF

FORCEON = FORCEOFF = VCC, no load

FORCEOFF = GND, all R_IN = GND

FORCEON = GND, FORCEOFF = V

CC,

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

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

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

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= T

MIN

to T

MAX

, 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, T

OUT

= ±2V

OUT

= ±12V, VCC= 0 or 3V to

5.5V, transmitters disabled

All transmitter outputs loaded with 3kΩ to ground

Receiver Positive or Negative Threshold to INVALID High

1 µsVCC= 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

±5.0Transmitter Output Voltage V

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

2.5mA each

INVH

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 5bt

INVL

Input Voltage Range -25 25 V

Receiver or Transmitter Edge to Transmitters Enabled

100 µsVCC= 5V, Figure 5bt

Input Voltage Range -25 25 V

±8IEC 1000-4-2 Contact Discharge

R_IN, T_OUT

±15Human Body Model

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 3kΩ and CL, TA = +25°C, unless otherwise noted.)

-6

-5

-4

-3

-2

-1

010002000 3000 4000 5000

MAX3221E/MAX3223E

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3221E-01

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

OUT+

T1 TRANSMITTING AT 250kbps T2 (MAX3223E) TRANSMITTING AT 15.6kbps

OUT-

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= 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%. Note 3: Transmitter skew is measured at the transmitter zero cross points.

PLH

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

PHL

SYMBOL



PHL

- t

PLH



PHL

- t

PLH



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= 3kΩ to 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 3kΩ and CL, TA= +25°C, unless otherwise noted.)

-6

-5

-4

-3

-2

-1

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

OUT+

OUT-

0 1000 2000 3000 4000 5000

MAX3243E

SLEW RATE vs. LOAD CAPACITANCE

MAX3243E-05

LOAD CAPACITANCE (pF)

SLEW RATE (V/µs)

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

020001000 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

MAX3221E MAX3223E MAX3243E

TQFN

DIP/

SO/

NAME

FUNCTION

14 1 19 1 — 22 EN

Recei ver E nab l e C ontr ol . D r i ve l ow for nor m al op er ati on. D r i ve hi g h to for ce the r ecei ver outp uts ( R_O U T) i nto a hi g h- i m p ed ance 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

14242423C1-

Negative terminal of the voltage doubler Charge-Pump Capacitor

351

29 C2+ Positive terminal of inverting Charge-Pump Capacitor

462

30 C2- Negative terminal of inverting Charge-Pump Capacitor

573

31 V- -5.5V generated by the charge pump

4-8 1-5 R_IN RS-232 Receiver Inputs

13, 14, 15, 17,18R_OUT TTL/CMOS Receiver Outputs

71091121 —

Output of the Valid Signal Detector. INVALID is enabled high if a valid RS-232 level is present on any receiver input.

811

12, 13,1410, 11,

T_IN TTL/CMOS Transmitter Inputs

912121423—

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

10 13

T_OUT RS-232 Transmitter Outputs

————2019

TTL/CMOS Noninverting Complementary Receiver Output. Always active.

11 14 16 18 25 24 GND Ground

12 15 17 19 26 26 V

+3.0V to +5.5V Supply Voltage

13 16 18 20 22 —

Force- Off Inp ut, acti ve l ow. D ri ve l ow to shut d ow n tr ansm itters, r ecei ver s (M AX 3243E, excep t R2OU TB), and on- b oar d char ge p ump . Thi s overr i d es all autom ati c ci r cui try and FORC E ON ( Tab l e 1) .

—————21SHDN Shutdown Control, Active Low

SSOP/

TSSOP

TQFN

7, 14 9, 16

8, 13 10, 15 15-19

10, 11 12, 13

6, 15 8, 17 9, 10, 11 6, 7, 8

SSOP/

TSSOP

SSOP/

TSSOP

THIN

QFN

INVALID

FORCEON

R2OUTB

FORCEOFF

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 VCCrange. 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 convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. They guarantee a 250kbps data rate with worst-case loads of 3kΩ in parallel with 1000pF, providing compatibility with PC-to-PC communication software such as LapLink™. Transmitters can be paralleled to drive multiple receivers. The MAX3243E has been specifically designed to drive serial mice. Figure 1 shows a complete 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-impedance 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)

MAX3221E MAX3223E MAX3243E

TQFN

DIP/

SO/

NAME FUNCTION

—————

N oni nver ti ng C om p l em entar y Recei ver O utp uts. Al w ays acti ve.

—————

9, 16,

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.

SSOP/

TSSOP

TQFN

SSOP/

TSSOP

SSOP/

TSSOP

THIN

QFN

19, 20 R_OUTB

25, 32

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 convert 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 receiver(s) in a high-impedance state. The MAX3243E’s receivers are high-impedance when the part is in shutdown (FORCEOFF = low).

The MAX3243E features an extra, always-active complementary output (R2OUTB). R2OUTB monitors receiver activity while the other receivers are highimpedance. This allows Ring Indicator to be monitored without forward biasing other devices connected to the receiver outputs. This is ideal for systems where V

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 feature, 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 onboard 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 transmitters 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 diagram for AutoShutdown operation.

MAX3243E

T1OUT

R2OUTB

5kΩ

UART

T1IN

THREE-STATED

LOGIC

TRANSITION

DETECTOR

R2IN

PROTECTION DIODE

R2OUT

FORCEOFF = GND

TO µP

RS-232

UART

SHDN = GND

GND

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

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

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

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 RS232 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 AutoShutdown 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 developed state-of-the-art structures to protect these pins against ESD of ±15kV without damage. The ESD structures 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.

FORCEON

Active

R2OUTB

(MAX3243E)

Active

High-Z

R_OUT

(MAX3221E/

MAX3223E)

Active

High-Z

FORCEOFF

Active

High-Z

Active

T_OUT

High-Z

Active

High-Z

Active

R_OUT

(MAX3243E)

High-Z

Active

High-Z

0 Yes

Normal Operation (AutoShutdown)

Yes

0 X

Normal Operation (Forced On)

Shutdown (Forced Off)

(MAX3221E/

MAX3223E)

VALID

RECEIVER

LEVEL

0 X

OPERATION

STATUS

0 ActiveHigh-Z1 High-Z Active

Shutdown (AutoShutdown)

No1

MAX3221E/MAX3223E/MAX3243E

10 ______________________________________________________________________________________

ESD protection can be tested in various ways; the transmitter 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

ESD Test Conditions

ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results.

Human Body Model

Figure 6a shows the Human Body Model, and Figure 6b shows the current waveform it generates when discharged 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

1.5kΩ resistor.

IEC1000-4-2

The IEC1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The MAX3221E/ MAX3223E/ MAX3243E help you design equipment that meets

V-

V+

INVL

INVALID REGION

RECEIVER

INPUT

VOLTAGE

(V)

INVALID

OUTPUT

(V)

INVH

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

INDETERMINATE

Figure 5. AutoShutdown Trip Levels

FORCEON

MASTER SHDN LINE

0.1µF1M

Ω

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 withstand 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 manufacturing. 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

100pF

1MΩ RD 1500Ω

HIGH-

VOLTAGE

SOURCE

DEVICE UNDER

TEST

Figure 7a. IEC1000-4-2 ESD Test Model

tr = 0.7ns to 1ns

30ns

60ns

100%

90%

10%

PEAK

Figure 7b. IEC1000-4-2 ESD Generator Current Waveform

Figure 6a. Human Body ESD Test Models

IP 100%

90%

36.8%

TIME

CURRENT WAVEFORM

PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)

10%

AMPERES

Figure 6b. Human Body Model Current Waveform

Ω

DISCHARGE

RESISTANCE

STORAGE CAPACITOR

HIGH-

VOLTAGE

SOURCE

50MΩ to 100MΩRD 330

CHARGE CURRENT

LIMIT RESISTOR

150pF

DEVICE UNDER

TEST

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 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-.

Power-Supply Decoupling

In most circumstances, a 0.1µF VCCbypass capacitor is adequate. In applications that are sensitive to powersupply 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 transmitter outputs are shown going to opposite RS-232 levels (one transmitter output is high, the other is low). Each transmitter is loaded with 3kΩ in 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 Vexceeds approximately -3V.

High Data Rates

The MAX3221E/MAX3223E/MAX3243E maintain the RS232 ±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 simultaneously 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 supplies. 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 regulated dual charge pump ensures the transmitters will supply at least ±5V during worst-case conditions. Figure 12a shows the transmitter outputs under increasing load current. The AutoShutdown feature does not work with a mouse, so FORCEOFF and FORCEON should be connected to V

. 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, C

BYPASS

(µF)

(V)

Table 3. Required Capacitor Values

10.223.0 to 5.5

Figure 8. Transmitter Outputs Exiting Shutdown or Powering Up

5V/div

2V/div

VCC = 3.3V C1–C4 = 0.1µF

40µs/div

FORCEON = FORCEOFF

T2OUT

T1OUT

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+

0.1µF

FORCEOFF

T_ OUT

T_ IN

GND

1000pF

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.

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

Auto-

Shutdown

—

Yes

—

Yes

—

Yes

—

HUMAN

BODY

MODEL

(kV)

±15

IEC 1000-4-2

CONTACT

DISCHARGE

(kV)

±8

IEC 1000-4-2

AIR-GAP

DISCHARGE

(kV)

±15

T1IN

5V/div

T1OUT

R1OUT

VCC = 3.3V

2µs/div

5V/div

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

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.

Compatible with all CMOS families.

3.33.3

COMPATIBILITY

VCCSUPPLY

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 12345678910

MAX2343E-FIG15

LOAD CURRENT PER TRANSMITTER (mA)

TRANSMITTER OUTPUT VOLTAGE (V)

OUT+

OUT-

OUT+

OUT-

VCC = 3.0V

___________________Chip Information

MAX3221E TRANSISTOR COUNT: 269 MAX3223E TRANSISTOR COUNT: 339 MAX3243E TRANSISTOR COUNT: 476 PROCESS: BiCMOS

PART

TEMP

RANGE

PINPACKAGE

MAX3243ECWI

0°C to +70°C

28 Wide SO

MAX3243ECAI

0°C to +70°C

28 SSOP

MAX3243EEWI

-40°C to +85°C

28 Wide SO

MAX3243EEAI

-40°C to +85°C

28 SSOP

MAX3243ECUI

0°C to +70°C

28 TSSOP

MAX3243EEUI

-40°C to +85°C

28 TSSOP

MAX3243ECTJ

0°C to +70°C

32 Thin QFN-EP (7mm x 7mm)*

MAX3243EETJ

-40°C to +85°C

32 Thin QFN-EP (7mm x 7mm)*

PKG CODE

—

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.

MAX3221E/MAX3223E/MAX3243E

±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,

RS-232 Transceivers with AutoShutdown

______________________________________________________________________________________ 15

COMPUTER SERIAL PORT

-V

GND

SERIAL

MOUSE

MAX3243E

FORCEOFF

R5OUT

R4OUT

R3OUT

R2OUT

R1OUT

R2OUTB

LOGIC

OUTPUTS

5kΩ

R5IN 8

R4IN

R3IN

R2IN 5

R1IN

RS-232 INPUTS

GND

LOGIC

INPUTS

T3IN

T2IN

T1IN

C2-

C2+

C1-

C1+

T3OUT

T2OUT 10

T1OUT 9

V-

V+

0.1µF

FORCEON

INVALID

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

R2OUT10

R1OUT15

FORCEOFF

INVALID 11

R2IN

GND

RS-232 OUTPUTS

TTL/CMOS

INPUTS

T2IN

T1IN

C2-

C2+

C1-

C1+

R1IN

T2OUT

T1OUT 17

V-

V+

0.1µF

BYPASS

+3.3V

RS-232 INPUTS

TO POWERMANAGEMENT UNIT

TTL/CMOS

OUTPUTS

5kΩ

MAX3243E

FORCEOFF

R5OUT

R4OUT

R3OUT

R2OUT

R1OUT

R2OUTB

LOGIC

OUTPUTS

5kΩ

R5IN 8

R4IN

R3IN

R2IN 5

R1IN

RS-232 INPUTS

GND

RS-232 OUTPUTS

LOGIC

INPUTS

T3IN

T2IN

T1IN

C2-

C2+

C1-

C1+

T3OUT

T2OUT 10

T1OUT 9

V-

V+

BYPASS

0.1µF

FORCEON

INVALID

TO POWER-

MANAGEMENT UNIT

+3.3V

MAX3221E*

FORCEON

R1OUT9

FORCEOFF

INVALID 10

GND

T1IN

C2-

C2+

C1-

C1+

R1IN 8

T1OUT 13

V-

V+

0.1µF

BYPASS

+3.3V

TO POWERMANAGEMENT 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

FORCEOFF

GND

T1OUT

C1-

V+

C1+

R1IN

R1OUT

FORCEON

T1IN

T2OUT

V-

C2-

C2+

T2IN

INVALID

R2OUT

R2IN

DIP/SSOP/TSSOP

MAX3223E

TOP VIEW

C1+

V+

C1-

C2+

C2-

V-

R1IN

FORCEOFF

GND

T1OUT

FORCEON

T1IN

INVALID

R1OUT

MAX3221E

SSOP/TSSOP

TQFN

N.C.

V-

C2-

C2+

C1+

V+

N.C.

T3IN

T2IN

T1IN

R5OUT

R4OUT

R3OUT

N.C.

17181920212223

R2OUT

R1OUT

R2OUTB

R1OUTB

SHDN

C1-

8765432

T3OUT

T2OUT

T1OUT

R5IN

R4IN

R3IN

R2IN

MAX3243E

R1IN

GND

TOP VIEW

C2+

C2-

V-

R1IN

R2IN

MAX3243E

SO/SSOP/TSSOP

R3IN

R4IN

R5IN

T1OUT

T2OUT

T3OUT

T3IN

T2IN

T1IN

C1+

V+

GND

C1-

FORCEON

FORCEOFF

INVALID

R2OUTB

R1OUT

R2OUT

R3OUT

R4OUT

R5OUT

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

Pin Configurations (continued)

C2+

V-

C1-

GND

FORCEON

VCC

12 11 9

V+

C1+

* EP = EXPOSED PADDLE

T1IN

INVALID

R1OUT

R1IN

MAX3221E

C2- T1OUT

FORCEOFF

TQFN

TOP VIEW

MAX3223E

TQFN

C1-

C2-

V-

C1+

R1IN

FORCEON

T1IN

T1OUT

FORCEOFF

15 14 12 11

V+

* EP = EXPOSED PADDLE

INVALID

R2OUT

R2IN

T2OUT

C2+

R1OUT

VCC

T2IN

GND

MAXIM MAX3221E, MAX3223E, MAX3243E User Guide

Specifications and Main Features

Frequently Asked Questions

User Manual