MAXIM MAX3224E, MAX3227E, MAX3244E, MAX3245E User Manual

________________General Description

The MAX3224E/MAX3225E/MAX3226E/MAX3227E/
MAX3244E/MAX3245E 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, ±8kV using IEC 1000-4-2 Contact Discharge,
and ±15kV using the Human Body Model.

All devices achieve a 1µA supply current using Maxim’s
revolutionary AutoShutdown Plus™ feature. These
devices automatically enter a low-power shutdown
mode when the RS-232 cable is disconnected or the
transmitters of the connected peripherals are inactive,
and the UART driving the transmitter inputs is inactive
for more than 30 seconds. They turn on again when
they sense a valid transition at any transmitter or receiv­er input. AutoShutdown Plus saves power without
changes to the existing BIOS or operating system.

The MAX3225E/MAX3227E/MAX3245E also feature
MegaBaud™ operation, guaranteeing 1Mbps for high­speed applications such as communicating with ISDN
modems. The MAX3224E/MAX3226E/MAX3244E guar­antee 250kbps operation. The transceivers have a pro­prietary low-dropout transmitter output stage enabling
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. The MAX3224E–MAX3227E feature a logic­level output (READY) that asserts when the charge
pump is regulating and the device is ready to begin
transmitting.

All devices are available in a space-saving TQFN,
SSOP, and TSSOP (MAX3224E/MAX3225E/MAX3244E/
MAX3245E) packages.

________________________Applications

Notebook, Subnotebook, and Palmtop Computers

Cellular Phones

Battery-Powered Equipment

Hand-Held 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/MAX3241E

†

/MAX3246E:
±15kV ESD-Protected, Down to 10nA, +3.0V to
+5.5V, Up to 1Mbps, True RS-232 Transceivers
(MAX3246E Available in UCSP™)

♦ For Low-Voltage or 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

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

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

RS-232 Transceivers with AutoShutdown Plus

________________________________________________________________ Maxim Integrated Products 1

19-1339; Rev 9; 2/07

PART

MAX3224E

MAX3225E

MAX3226E

1/1

2/2

2/2

NO. OF

DRIVERS/

RECEIVERS

READY

OUTPUT

✔

✔

✔

Auto-

Shutdown

Plus

✔

✔

✔

250k

1M

250k

GUARANTEED

DATA RATE

(bps)

MAX3227E

MAX3244E

MAX3245E

3/5

3/5

1/1

✔

—

—

✔

✔

✔

1M

250k

1M

Ordering Information continued at end of data sheet.

*EP = Exposed paddle.

†

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.

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

_____________________ Selector Guide

Ordering Information

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.

PART

MAX3224ECTP

MAX3224ECUP

MAX3224ECAP

MAX3224ECPP

MAX3224EETP

MAX3224EEUP

MAX3224EEAP

MAX3224EEPP

MAX3224EAAP

TEMP

RANGE

0°C to +70°C

0°C to +70°C
0°C to +70°C

0°C to +70°C

-40°C to +85°C

-40°C to +85°C

-40°C to +85°C

-40°C to +85°C

-40°C to +125°C

PIN

PKG

20 TQFN-

EP*

20 TSSOP —

20 SSOP —

20 Plastic

DIP

20 TQFN-

EP*

20 TSSOP —

20 SSOP —

20 Plastic

DIP

20 SSOP —

PKG
CODE

T2055-5

—

T2055-5

—

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

±15kV ESD-Protected, 1µA, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; C1= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= T

MIN

to T

MAX

,

unless otherwise noted. Typical values are at T

A

= +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, FORCEON, FORCEOFF to GND ................ -0.3V to +6V

R_IN to GND ....................................................................±25V

Output Voltages

T_OUT to GND.............................................................±13.2V

R_OUT, INVALID, READY to GND .........-0.3V to (V

CC

+ 0.3V)

Short-Circuit Duration

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

Continuous Power Dissipation (T

A

= +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 TQFN (derate 21.3mW/°C above +70°C) ....1702.1mW

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

28-Pin Wide SO (derate 12.5mW/°C above +70°C)............1W

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

28-Pin TSSOP (derate 12.8mW/°C above +70°C) .......1026mW

36-Pin TQFN (derate 26.3mW/°C above +70°C)...........2105mW

Operating Temperature Ranges

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

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

MAX32_ _EAA_..............................................-40°C to +125°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

FORCEON = GND, FORCEOFF = VCC,
all R_IN idle, all T_IN idle

TA= +25°C

VCC= 3.3V

T_IN, FORCEON,

FORCEOFF

CONDITIONS

kΩ357Input Resistance

V0.5Input Hysteresis

1.8 2.4

V

1.5 2.4

Input Threshold High

0.8 1.5

V

0.6 1.2

Input Threshold Low

V-25 +25Input Voltage Range

V

VCC- 0.6 VCC- 0.1

Output Voltage High

V0.4Output Voltage Low

µA110Supply Current, Shutdown

µA110

Supply Current,
AutoShutDown Plus

µA±0.05 ±10Output Leakage Current

µA±0.01 ±1

Transmitter Input Hysteresis V0.5

V

2.4

Input Logic Threshold High

mA0.3 1

Supply Current,
AutoShutDown Plus Disabled

V0.8Input Logic Threshold Low

2

UNITSMIN TYP MAXSYMBOLPARAMETER

FORCEOFF = GND

TA= +25°C

VCC= 5.0V

VCC= 3.3V

TA= +25°C

R_OUT (MAX3244E/MAX3245E), receivers
disabled

T_IN, FORCEON, FORCEOFF

VCC= 5.0V

FORCEON = FORCEOFF = VCC, no load

T_IN, FORCEON, FORCEOFF

I

OUT

= -1.0mA

VCC= 3.3V

I

OUT

= 1.6mA

DC CHARACTERISTICS (VCC= 3.3V or 5.0V, TA= +25°C)

LOGIC INPUTS AND RECEIVER OUTPUTS

RECEIVER INPUTS

Input Leakage Current

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

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

RS-232 Transceivers with AutoShutdown Plus

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; C1= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= T

MIN

to T

MAX

,

unless otherwise noted. Typical values are at T

A

= +25°C.)

CONDITIONS

Ω300 10MOutput Resistance

V±5 ±5.4Output Voltage Swing

UNITSMIN TYP MAXSYMBOLPARAMETER

Figure 4a

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

2.5mA each

s15 30 60t

AUTOSHDN

Receiver or Transmitter Edge to
Transmitters Shutdown

µs100t

WU

Receiver or Transmitter Edge to
Transmitters Enabled

µs30t

INVL

Receiver Positive or Negative
Threshold to INVALID Low

µs1t

INVH

Receiver Positive or Negative
Threshold to INVALID High

V

V

CC

- 0.6

INVALID, READY
Output Voltage High
(MAX3224E–MAX3227E)

V0.4

INVALID, READY
Output Voltage Low
(MAX3224E–MAX3227E)

V-0.3 +0.3

Receiver Input Threshold to
INVALID Output Low

-2.7

V

2.7

Receiver Input Threshold to
INVALID Output High

±15

±8R_IN, T_OUT kV

±15

V±5Transmitter Output Voltage

µA±25Output Leakage Current

±60 mAOutput Short-Circuit Current

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

All transmitter outputs loaded with 3kΩ to
ground

VCC= 5V, Figure 5b (Note 2)

VCC= 5V, Figure 5b (Note 2)

VCC= 5V, Figure 4b

VCC= 5V, Figure 4b

I

OUT

= -1.0mA

I

OUT

= -1.6mA

Figure 4a

Negative threshold

Positive threshold

Human Body Model

VCC= 0 or 3V to 5.5V, V

OUT

= ±12V,

Transmitters disabled

IEC1000-4-2 Contact Discharge

IEC1000-4-2 Air Discharge

TRANSMITTER OUTPUTS

MOUSE DRIVEABILITY (MAX3244E/MAX3245E)

ESD PROTECTION

AutoShutdown Plus (FORCEON = GND, FORCEOFF = VCC)

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

±15kV ESD-Protected, 1µA, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus

4 _______________________________________________________________________________________

TIMING CHARACTERISTICS—MAX3224E/MAX3226E/MAX3244E

(VCC= +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; C1= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= T

MIN

to T

MAX

,

unless otherwise noted. Typical values are at T

A

= +25°C.)

TIMING CHARACTERISTICS—MAX3225E/MAX3227E/MAX3245E

(VCC= +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; C1= 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA= T

MIN

to T

MAX

,

unless otherwise noted. Typical values are at T

A

= +25°C.)

Note 2: A transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic thresholds.
Note 3: Transmitter skew is measured at the transmitter zero cross points.

CL= 150pF
to 1000pF

R_IN to R_OUT, CL= 150pF

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

VCC= 3.3V, TA= +25°C,
RL= 3kΩ to 7kΩ,
measured from +3V to -3V
or -3V to +3V, one trans­mitter switching

Normal operation (MAX3244E only)

Normal operation (MAX3244E only)

(Note 3)

CONDITIONS

0.15t

PLH

µs

0.15t

PHL

kbps250Maximum Data Rate

Receiver Propagation Delay

V/µs630Transition-Region Slew Rate

ns200Receiver Output Enable Time

ns200Receiver Output Disable Time

ns100

⏐

t

PHL

- t

PLH

⏐

Transmitter Skew

ns50

⏐

t

PHL

- t

PLH ⏐

Receiver Skew

UNITSMIN TYP MAXSYMBOLPARAMETER

VCC= 4.5V to 5.5V, RL= 3kΩ,
C

L

= 1000pF, one transmitter switching

VCC= 3.0V to 4.5V, RL= 3kΩ,
CL= 250pF, one transmitter switching

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

VCC= 3.3V, TA= +25°C,
RL= 3kΩ to 7kΩ, CL= 150pF to 1000pF,
measured from +3V to -3V or -3V to +3V,
one transmitter switching

(Note 3)

R_IN to R_OUT, CL= 150pF

Normal operation (MAX3245E only)

Normal operation (MAX3245E only)

CONDITIONS

1000

1000

kbps

250

Maximum Data Rate

V/µs24 150Transition-Region Slew Rate

ns50

⏐

t

PHL

- t

PLH

⏐

Receiver Skew

ns25

⏐

t

PHL

- t

PLH

⏐

Transmitter Skew

µs

0.15t

PHL

Receiver Propagation Delay

0.15t

PLH

ns200Receiver Output Enable Time

ns200Receiver Output Disable Time

UNITSMIN TYP MAXSYMBOLPARAMETER

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

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

RS-232 Transceivers with AutoShutdown Plus

_______________________________________________________________________________________ 5

__________________________________________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.)

0

200

180

160

140

120

100

80

60

40

20

-40 0 20-20 406080100

MAX3224E–MAX3227E

READY TURN-OFF TIME

vs. TEMPERATURE

MAX3224-7/44/45E-09

TEMPERATURE (°C)

READY TURN-OFF TIME (ns)

MAX3224E/MAX3226E

TRANSMITTER OUTPUT VOLTAGE

6
5
4
3
2
1
0

-1

-2

-3

-4

TRANSMITTER OUTPUT VOLTAGE (V)

-5

-6

7.5

5.0

2.5

0

-2.5

-5.0

TRANSMITTER OUTPUT VOLTAGE (V)

-7.5

50

45

40

35

30

25

20

15

TRANSMITTER SKEW (ns)

10

5

0

vs. LOAD CAPACITANCE

T1 TRANSMITTING AT 250kbps
T2 (MAX3224E) TRANSMITTING AT 15.6kbps

0 10002000300040005000

LOAD CAPACITANCE (pF)

MAX3225E/MAX3227E

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

2Mbps

1 TRANSMITTER AT FULL DATA RATE
1 TRANSMITTER AT 1/16 DATA RATE

(MAX3225E)
LOAD = 3kΩ + C

01000500 1500 2000 2500

L

LOAD CAPACITANCE (pF)

MAX3225E/MAX3227E

TRANSMITTER SKEW

vs. LOAD CAPACITANCE

1 TRANSMITTER AT 512kbps
1 TRANSMITTER AT 30kbps

(MAX3225E)
LOAD = 3kΩ + C

0 1000500 1500 2000 2500 3000

L

AVERAGE: 10 PARTS

LOAD CAPACITANCE (pF)

2Mbps

V

V

1.5Mbps

1.5Mbps

OUT+

OUT-

1Mbps

1Mbps

16

14

12

MAX3224-7/44/45E-01

10

SLEW RATE (V/μs)

80

70

60

MAX3224-7/44/45E-04

50

40

30

SLEW RATE (V/μs)

20

10

MAX3224-7/44/45E-07

READY TURN-ON TIME (μs)

MAX3224E/MAX3226E

SLEW RATE vs. LOAD CAPACITANCE

-SLEW

8

6

4

2

0

0 1000 2000 3000 4000 5000

+SLEW

FOR DATA RATES UP TO 250kbps

LOAD CAPACITANCE (pF)

MAX3225E/MAX3227E

SLEW RATE vs. LOAD CAPACITANCE

-SLEW

+SLEW

1 TRANSMITTER AT 1Mbps
1 TRANSMITTER AT 62.5kbps (MAX3225E)

0

0 500 1000 1500 2000 2500

LOAD CAPACITANCE (pF)

MAX3224E–MAX3227E
READY TURN-ON TIME

vs. TEMPERATURE

38

36

34

32

30

28

26

24

22

20

-40 0 20-20 40 60 80 100
TEMPERATURE (°C)

45

40

35

MAX3224-7/44/45E-02

30

25

20

15

SUPPLY CURRENT (mA)

10

5

0

100

90

80

MAX3224-7/44/45E-05

70

60

50

40

30

SUPPLY CURRENT (mA)

20

10

0

MAX3224-7/44/45E-08

MAX3224E/MAX3226E

OPERATING SUPPLY CURRENT

vs. LOAD CAPACITANCE

250kbps

120kbps

20kbps

T1 TRANSMITTING AT 250kbps
T2 (MAX3224E) TRANSMITTING AT 15.6kbps

020001000 3000 4000 5000

LOAD CAPACITANCE (pF)

MAX3225E/MAX3227E

OPERATING SUPPLY CURRENT

vs. LOAD CAPACITANCE

1 TRANSMITTER AT FULL DATA RATE
1 TRANSMITTER AT 1/16 DATA RATE

(MAX3225E)
LOAD = 3kΩ + C

2Mbps

0 500 1000 1500 2000 2500

L

1.5Mbps

1Mbps

LOAD CAPACITANCE (pF)

MAX3224-7/44/45E-03

MAX3224-7/44/45E-06

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

±15kV ESD-Protected, 1µA, 1Mbps, 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus

6 _______________________________________________________________________________________

_____________________________Typical Operating Characteristics (continued)

(V

CC

= +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

0

1

2

3

4

5

6

0 1000 2000 3000 4000 5000

MAX3244E

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3224-7/44/45E-10

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

1 TRANSMITTER AT 250kbps
2 TRANSMITTERS AT 15.6kbps

V

OUT+

V

OUT-

0

4

2

8

6

12

10

14

0 1000 2000 3000 4000 5000

MAX3244E

SLEW RATE vs. LOAD CAPACITANCE

MAX3224-7/44/45E-11

LOAD CAPACITANCE (pF)

SLEW RATE (V/

μ

s)

0

30

20

10

40

50

60

0 20001000 3000 4000 5000

MAX3244E

OPERATING SUPPLY CURRENT

vs. LOAD CAPACITANCE

MAX3224-7/44/45E-12

LOAD CAPACITANCE (pF)

SUPPLY CURRENT (mA)

250kbps

120kbps

20kbps

1 TRANSMITTER AT 250kbps
2 TRANSMITTERS AT 15.6kbps

-7.5

0

-2.5

-5.0

2.5

5.0

7.5

0 800400 1200 1600 2000

MAX3245E

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3224-7/44/45E-13

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

2Mbps

2Mbps

1.5Mbps

1.5Mbps

1Mbps

1Mbps

1 TRANSMITTER AT FULL DATA RATE
2 TRANSMITTERS AT 1/16 DATA RATE

0

20

10

40

30

60

50

70

90

80

100

0 400 800 1200 1600 2000

MAX3245E

OPERATING SUPPLY CURRENT

vs. LOAD CAPACITANCE

MAX3224-7/44/45E-15

LOAD CAPACITANCE (pF)

SUPPLY CURRENT (mA)

2Mbps

1.5Mbps

1Mbps

1 TRANSMITTER AT FULL DATA RATE
2 TRANSMITTERS AT 1/16 DATA RATE

0

20

10

40

30

60

50

70

0 400 800 1200 1600 2000

MAX3245E

SLEW RATE vs. LOAD CAPACITANCE

MAX3224-7/44/45E-14

LOAD CAPACITANCE (pF)

SLEW RATE (V/

μ

s)

1 TRANSMITTER AT 1Mbps
2 TRANSMITTERS AT 62.5kbps

0

15

10

5

20

25

30

35

40

45

50

0 1000 2000 3000

MAX3245E

TRANSMITT SKEW

vs. LOAD CAPACITANCE

MAX3224-7/44/45E-16

LOAD CAPACITANCE (pF)

TRANSMITTER SKEW (ns)

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

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

RS-232 Transceivers with AutoShutdown Plus

_______________________________________________________________________________________ 7

______________________________________________________________ Pin Description

PIN

MAX3224E
MAX3225E

TQFN

19 1 14 1 — — READY

1 2 16 2 28 31 C1+

20 3 15 3 27 30

2 4 1 4 24 26 C1-

3 5 2 5 1 33 C2+

DIP/

SSOP/

TSSOP

MAX3226E
MAX3227E

TQFN

SSOP/

TSSOP

MAX3244E
MAX3245E

SO/ SSOP/ TSSOP

MAX3245E

(TQFN)

NAME FUNCTION

Ready to Transmit Output,
active-high. READY is
enabled high when V- goes
below -4V and the device is
ready to transmit.

Positive Terminal of Voltage­Doubler Charge-Pump
Capacitor

V+

+5.5V generated by the
charge pump

Negative Terminal of
Voltage-Doubler Charge­Pump Capacitor

Positive Terminal of
Inverting Charge-Pump
Capacitor

4 6 3 6 2 34 C2-

5747 3 35 V-

6, 15 8, 17 10 13 9, 10, 11 7, 8, 9 T_OUT

7, 14 9, 16 5 8 4-8 1-5 R_IN

8, 13 10, 15 6 9

911710

15-19

21 23 INVALID

15, 16, 17,

19, 20

R_OUT

Negative Terminal of
Inverting Charge-Pump
Capacitor

-5.5V Generated by the
Charge Pump

RS-232 Transmitter Outputs

RS-232 Receiver Inputs

TTL/CMOS Receiver
Outputs

Valid Signal Detector
Output, active low. A logic
high indicates that a valid
RS-232 level is present on a
receiver input.

MAX3224E–MAX3227E/MAX3244E/MAX3245E

†

±15kV ESD-Protected, 1µA, 1Mbps 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus

8 _______________________________________________________________________________________

______________________________________________________________ Pin Description

_______________Detailed Description

Dual Charge-Pump Voltage Converter

The MAX3224E–MAX3227E/MAX3244E/MAX3245E’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 range. The charge
pump operates in discontinuous mode: if the output
voltages are less than 5.5V, the charge pump is

enabled; if the output voltages exceed 5.5V, the
charge-pump is disabled. Each charge pump requires
a flying capacitor (C1, C2) and a reservoir capacitor
(C3, C4) to generate the V+ and V- supplies.

The READY output (MAX3224E–MAX3227E) is low
when the charge pumps are disabled in shutdown
mode. The READY signal asserts high when V- goes
below -4V.

PIN

MAX3224E
MAX3225E

TQFN

10, 11 12, 13 8 11 12-14 11, 12, 13 T_IN

12 14 9 12 23 25 FORCEON

16 18 11 14 25 27

17 19 12 15 26 29

18 20 13 16 22 24

— — — — 20 21 R2OUTB

DIP/

SSOP/

TSSOP

MAX3226E
MAX3227E

TQFN

SSOP/

TSSOP

MAX3244E
MAX3245E

DIP/ SSOP/ TSSOP

MAX3245E

TQFN

NAME

GND

V

CC

FORCEOFF

FUNCTION

TTL/CMOS Transmitter
Inputs

Force-On Input, Active High.
Drive high to override
AutoShutdown Plus, keeping
transmitters and receivers
on (FORCEOFF must be
high) (Table 1).

Ground

+3.0V to +5.5V Single
Supply Voltage

Force-Off Input, Active Low.
Drive low to shut down
transmitters, receivers
(except R2OUTB), and
charge pump. This
overrides AutoShutdown
Plus and FORCEON (Table

1).

TTL/CMOS Noninverting
Complementary Receiver
Outputs. Always active.

———— —

EP — EP — — EP EP

6, 10, 14,

18, 22, 28,

32, 36

N.C.

No Connection. Not
internally connected.

Exposed Paddle. Solder the
exposed paddle to the
ground plane or leave
unconnected.