MAX3221-MAX3243.pdf

19-0306; Rev 7; 10/02

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

_______________General Description

The MAX3221/MAX3223/MAX3243 achieve 1µA supply

current with Maxim’s revolutionary AutoShutdown™ fea-

ture. 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 3V-

powered EIA/TIA-232 and V.28/V.24 communications

interfaces intended for notebook computer applica-

tions. 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 pro-

vides compatibility with popular software for communi-

cating 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 bias-

ing the protection diodes in a UART that may have V CC

completely removed.

____________________________Features

Small 0.1µF Capacitors

True RS-232 Operation from V CC = +3.0V to +5.5V

Meets EIA/TIA-562 Specifications Down to 2.7V

Guaranteed 120kbps Data Rate

6V/µs Min Guaranteed Slew Rate

Smallest Single-Supply RS-232 Transceiver

(MAX3221)

Guaranteed Mouse Driveability (MAX3243)

Small TSSOP Package (MAX3223/MAX3243)

________________________Applications

Notebook, Subnotebook, and Palmtop Computers

Battery-Powered Equipment

Hand-Held Equipment

Peripherals

Printers

______________Ordering Information

PART

MAX3221 CAE

TEMP RANGE

PIN-PACKAGE

16 SSOP

0°C to +70°C

MAX3221CUE †

0°C to +70°C

16 TSSOP

MAX3221EAE

-40°C to +85°C

16 SSOP

MAX3221EUE †

-40°C to +85°C

16 TSSOP

_____________________Selector Guide

MAX3223 CPP

MAX3223CAP

0°C to +70°C

20 Plastic DIP

20 SSOP

0°C to +70°C

PART

Rx V CC RANGE (V) AutoShutdown

MAX3223CUP

0°C to +70°C

20 TSSOP

MAX3221

MAX3223

MAX3243

3.0 to 5.5

Yes

MAX3223EPP

-40°C to +85°C

20 Plastic DIP

MAX3223EAP

-40°C to +85°C

20 SSOP

MAX3223EUP

-40°C to +85°C

20 TSSOP

Pin Configurations appear at end of data sheet.

Typical Operating Circuits appear at end of data sheet.

MAX3243 CWI

0°C to +70°C

28 Wide SO

MAX3243CAI

0°C to +70°C

28 SSOP

MAX3243CUI

0°C to +70°C

28 TSSOP

† Future product—contact factory for availability.

AutoShutdown is a trademark of Maxim Integrated Products.

MAX3243EWI

-40°C to +85°C

28 Wide SO

MAX3243EAI

-40°C to +85°C

28 SSOP

MAX3243EUI

-40°C to +85°C

28 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.

________________________________________________________________ Maxim Integrated Products 1

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.

1µA Supply Current Achieved with AutoShutdown

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

ABSOLUTE MAXIMUM RATINGS

16-Pin SSOP (derate 7.14mW/°C above +70°C) ...........571mW

16-Pin TSSOP (derate 6.70mW/°C above +70°C) .........533mW

20-Pin Plastic DIP (derate 11.11mW/°C above +70°C)....889mW

20-Pin SSOP (derate 8.00mW/°C above +70°C) ...........640mW

20-Pin TSSOP DIP (derate 7.00mW/°C above +70°C).....559mW

28-Pin Wide SO (derate 12.50mW/°C above +70°C) ............1W

28-Pin SSOP (derate 9.52mW/°C above +70°C) ...........762mW

28-Pin TSSOP (derate 8.70mW/°C above +70°C) .........696mW

Operating Temperature Ranges

MAX32_ _C_ _.......................................................0°C to +70°C

MAX32_ _E_ _ ....................................................-40°C to +85°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS

(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

DC CHARACTERISTICS

Supply Current, AutoShutdown

All R_IN open, FORCEON = GND,

FORCEOFF = V CC

FORCEOFF = GND

FORCEON = FORCEOFF = V CC ,

no load

1.0

µA

V CC = 3.3V

or 5.0V,

T A = +25°C

Supply Current, Shutdown

1.0

µA

Supply Current,

AutoShutdown Disabled

0.3

1.0

LOGIC INPUTS AND RECEIVER OUTPUTS

Input Logic Threshold Low

T_IN, FORCEON, FORCEOFF, EN (MAX3223)

0.8

Input Logic Threshold High

T_IN, EN, FORCEON, FORCEOFF

V CC = 3.3V

V CC = 5.0V

2.0

2.4

Input Leakage Current

T_IN, EN, FORCEON, FORCEOFF

±0.01

±1.0

µA

Output Leakage Current

Receivers disabled

±0.05

±10

µA

Output Voltage Low

I OUT = 1.6mA

0.4

Output Voltage High

I OUT = -1.0mA

V CC - 0.6 V CC - 0.1

AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = V CC )

Receiver Input Thresholds to

Transmitters Enabled

Figure 5

Positive threshold

Negative threshold

2.7

-2.7

Receiver Input Thresholds to

Transmitters Disabled

1µA supply current, Figure 5

-0.3

0.3

INVALID Output Voltage Low

I OUT = 1.6mA

0.4

INVALID Output Voltage High

I OUT = -1.0mA

V CC - 0.6

Receiver Threshold to

Transmitters Enabled (t WU )

Figure 5

250

µs

Receiver Positive or Negative

Threshold to INVALID High (t INVH )

Figure 5

µs

Receiver Positive or Negative

Threshold to INVALID Low (t INVL )

Figure 5

µs

2 _______________________________________________________________________________________

V CC ...........................................................................-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)

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

ELECTRICAL CHARACTERISTICS (continued)

(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

RECEIVER INPUTS

Input Voltage Range

-25

Input Threshold Low

T A = +25°C

V CC = 3.3V

0.6

1.2

V CC = 5.0V

0.8

1.5

Input Threshold High

T A = +25°C

V CC = 3.3V

1.5

2.4

V CC = 5.0V

1.8

2.4

Input Hysteresis

0.3

Input Resistance

T A = +25°C

Ω

TRANSMITTER OUTPUTS

Output Voltage Swing

All transmitter outputs loaded with 3k Ω to ground

±5.0

±5.4

Output Resistance

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

300

10M

Ω

Output Short-Circuit Current

±35

±60

Output Leakage Current

V OUT = ±12V, V CC = 0V or 3.0V to 5.5V,

transmitters disabled

±25

µA

MOUSE DRIVEABILITY (MAX3243)

Transmitter Output Voltage

to GND, T1OUT and

T2OUT loaded with 2.5mA each

Ω

±5

TIMING CHARACTERISTICS

Maximum Data Rate

R L = 3k

Ω

, C L = 1000pF, one transmitter switching

120

235

kbps

Receiver Propagation Delay

Receiver input to receiver output,

C L = 150pF

t PHL

0.3

µs

t PLH

0.3

Receiver Output Enable Time

Normal operation

200

Receiver Output Disable Time

Normal operation

200

Transmitter Skew

t PHL - t PLH

MAX3221/MAX3223

MAX3243

200

1000

Receiver Skew

t PHL - t PLH

MAX3221/MAX3223

MAX3243

100

500

V CC = 3.3V,

R L = 3k

Ω

to 7k

Ω

C L = 200pF to 2500pF

8.0

Transition-Region Slew Rate

T A = +25°C,

measured from +3V to

-3V or -3V to +3V

V/µs

C L = 200pF to 1000pF

Note 2: C1–C4 = 0.1µF, tested at 3.3V ±10%. C1 = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%.

_______________________________________________________________________________________ 3

T1IN = T2IN = GND, T3IN = V CC ,

T3OUT loaded with 3k

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

__________________________________________Typical Operating Characteristics

(V CC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3k Ω , T A = +25°C, unless otherwise noted.)

MAX3221/MAX3223

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3221/MAX3223

SLEW RATE

vs. LOAD CAPACITANCE

MAX3221/MAX3223

SUPPLY CURRENT vs. LOAD CAPACITANCE

WHEN TRANSMITTING DATA

MAX3221/3223-03

V OUT+

235kbps

-SLEW

120kbps

-1

+SLEW

-2

-3

-4

V OUT-

FOR DATA RATES UP TO 235kbps

20kbps

-5

-6

1000

2000

3000

4000

5000

150 500

1000

2000

3000

4000

5000

1000

2000

3000

4000

5000

LOAD CAPACITANCE (pF)

MAX3243

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3243

SLEW RATE

vs. LOAD CAPACITANCE

MAX3243

SUPPLY CURRENT vs. LOAD

CAPACITANCE WHEN TRANSMITTING DATA

7.5

V OUT +

235kbps

5.0

2.5

-SLEW

120kbps

1 TRANSMITTER AT 235kbps

2 TRANSMITTERS AT 30kbps

-2.5

20kbps

+SLEW

V OUT -

-5.0

ALL OUTPUTS LOADED WITH 3k

Ω

+C L

F CHARGE-PUMP CAPACITORS

FOR ALL DATA RATES UP TO 235kbps

-7.5

1000

2000

3000

4000

5000

1000

2000

3000

4000

5000

1000

2000

3000

4000

5000

LOAD CAPACITANCE (pF)

4 _______________________________________________________________________________________

0.1

1µA Supply-Current, True +3V to +5.5V

RS-232 Transceivers with AutoShutdown

______________________________________________________________Pin Description

NAME

FUNCTION

MAX3221

MAX3223

MAX3243

—

Receiver Enable Control. Drive low for normal operation. Drive high to force

the receiver outputs into a high-Z state.

C2+

Positive terminal of inverting charge-pump capacitor

C2-

Negative terminal of inverting charge-pump capacitor

V-

-5.5V generated by the charge pump

9, 16

8, 17

12, 13

10, 15

4–8

9, 10, 11

12, 13, 14

15–19

R_IN

RS-232 Receiver Inputs

T_OUT

RS-232 Transmitter Outputs

T_IN

TTL/CMOS Transmitter Inputs

R_OUT

TTL/CMOS Receiver Outputs

—

R2OUTB

Noninverting Receiver Output—active in shutdown

INVALID

Output of the valid signal detector. Indicates if a valid RS-232 level is pres-

ent on receiver inputs logic “1”.

FORCEOFF

Drive low to shut down transmitters and on-board power supply. This over-

rides all automatic circuitry and FORCEON (Table 1).

FORCEON

Drive high to override automatic circuitry keeping transmitters on

(FORCEOFF must be high) (Table 1).

C1-

Negative terminal of the voltage doubler charge-pump capacitor

GND

Ground

V CC

+3.0V to +5.5V Supply Voltage

V+

+5.5V generated by the charge pump

C1+

Positive terminal of the voltage doubler charge-pump capacitor

_______________Detailed Description

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 120kbps data rate with worst-case loads of

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 (V CC ) 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.

in parallel with 1000pF, providing compatibility with

PC-to-PC communication software (such as Laplink™).

Typically, the MAX3221/MAX3223/MAX3243 can oper-

ate at data rates of 235kbps. Transmitters can be paral-

leled to drive multiple receivers or mice (MAX3243).

Figure 1 shows a complete system connection.

When FORCEOFF is driven to ground, or the Auto-

Shutdown circuitry senses invalid voltage levels at all

receiver inputs, the transmitters are disabled and the

outputs are forced into a high-impedance state.

LapLink is a trademark of Traveling Software.

_______________________________________________________________________________________ 5

Ω

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