MAXIM MAX3238E, MAX3248E Technical data

________________________________________________________________ Maxim Integrated Products 1

General Description

The MAX3238E/MAX3248E transceivers use Maxim’s
revolutionary AutoShutdown Plus™ feature to achieve
10nA supply current. These devices shut down the on­board power supply and drivers when they do not sense
a valid signal transition on either the receiver or transmit­ter inputs. This occurs if the RS-232 cable is disconnect­ed or if the transmitters of the connected peripheral are
turned off. The devices turn on again when a valid transi­tion is applied to any RS-232 receiver or transmitter input.
AutoShutdown Plus automatically achieves this power
savings through its on-board circuitry, as no changes are
required to the existing BIOS or operating system.

All RS-232 inputs and outputs, as well as the logic I/O
pins, have enhanced ESD protection to ±15kV. The addi­tional ESD protection on the logic I/O pins makes the
MAX3238E/MAX3248E ideal for cell phone data cable
applications because it eliminates the need for costly
external TransZorb™or protection schemes.

The MAX3238E/MAX3248E contain five drivers and three
receivers and are 3V-powered EIA/TIA-232 and V.28/V.24
communication interfaces intended for cell phones, data
cables, and modem applications. A proprietary, high-effi­ciency, dual charge-pump power supply and a low­dropout transmitter combine to deliver true RS-232
performance from a single +3.0V to +5.5V supply. A
guaranteed data rate of 250kbps provides compatibility
with popular software for communicating with personal
computers.

The MAX3238E and the MAX3248E differ only in their
input logic thresholds. The MAX3238E has standard logic
thresholds, while the MAX3248E has low-level logic
thresholds of 0.6V to 1.2V, which are ideal for 1.8V sys­tems.

The transmitter inputs, FORCEON, and FORCEOFF have
a 400kΩ active positive feedback resistor. Once driven to
a valid logic level, they will retain this level if the driving
signal is removed or goes high impedance. Unused
transmitter and logic inputs may be left unconnected. The
MAX3238E/MAX3248E can operate with supply voltages
ranging from +3.0V to +5.5V.

Applications

Features

♦ Enhanced ESD Protection on RS-232 I/O Pins and

All Logic Pins

±15kV—Human Body Model
±8kV—IEC 1000-4-2 Contact Discharge
±15kV—IEC 1000-4-2 Air-Gap Discharge

♦ Guaranteed Data Rate: 250kbps

♦ 10nA Low-Power Shutdown with Receivers Active

♦ Schmitt Triggers on All Inputs

♦ Flow-Through Pinout

♦ Meets EIA/TIA-232 Specifications Down to 3.0V

♦ Guaranteed 6V/µs Slew Rate

♦ Low-Level Logic Thresholds (MAX3248E)

♦ RS-232-Compatible Outputs to 2.7V

MAX3238E/MAX3248E

†

+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers

with ±15kV ESD-Protected I/O and Logic Pins

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

C1+

V+

V

CC

C1-

T1IN

T2IN

INVALID

T3IN

R1OUT

R2OUT

T4IN

R3OUT

T5IN

R1OUTB

FORCEOFF

FORCEON

T5OUT

R3IN

T4OUT

R2IN

R1IN

T3OUT

T2OUT

T1OUT

V-

C2-

GND

C2+

SSOP

TOP VIEW

MAX3238E
MAX3248E

___________________Pin Configuration

19-1632; Rev 1; 6/01

Ordering Information

AutoShutdown Plus is a trademark of Maxim Integrated Products.

TransZorb is a trademark of General Semiconductor Industries, 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; and other
patents pending.

Cellular Data Cables
Modems
Battery-Powered Equipment

Peripherals
Data Cradles
Printers

Typical Operating Circuit appears at end of data sheet.

28 SSOP

28 SSOP

28 SSOP

28 SSOP

PIN-PACKAGETEMP. RANGE

0°C to +70°C

-40°C to +85°C

0°C to +70°C

-40°C to +85°CMAX3248EEAI

MAX3248ECAI

MAX3238EEAI

MAX3238ECAI

PART

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.

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.

MAX3238E/MAX3248E

+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and
C2–C4 = 0.33µF (tested at 5.0V ±10%), T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

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 ..............................-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 (one at a time) ............................................Continuous

Continuous Power Dissipation (T

A

= +70°C)

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

Operating Temperature Ranges

MAX3238ECAI/MAX3248ECAI ...........................0°C to +70°C

MAX3238EEAI/MAX3248EEAI .........................-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 a maximum magnitude of +7V, but their absolute difference can not exceed +13V.

1.10 1.2

1.15 1.6

0.95 1.2

MAX3248E

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 5.0V

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 3.3V

T_IN (active)

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 5.0V

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 3.3V

T_IN (active)

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 5.0V

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 3.3V

T_IN (active)

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 5.0V

FORCEON, FORCEOFF, and T_IN
wake-up threshold; V

CC

= 3.3V

T_IN (active)

PARAMETER MIN TYP MAX UNITS

Input Logic Threshold Low

0.8 1.20

V

Supply Current, AutoShutdown Plus
Disabled

0.5 2.0 mA

Supply Current, AutoShutdown Plus

Input Logic Threshold High

1.60 2.0

0.75 6 µA

V

10 300

2.10 2.4

1.30 2.0

MAX3238E

0.6 0.7

0.8 1.45

0.6 1.0

0.6 0.85

0.8 1.00

MAX3248E

Supply Current, Shutdown 10 300 nA

CONDITIONS

FORCEOFF = GND, R_IN = GND, T_IN = VCCor GND

MAX3238E

FORCEON = FORCEOFF = VCC, no load

Receivers idle, T_IN = VCCor GND, FORCEON =
GND, FORCEOFF = V

CC

R_IN = FORCEON = GND, FORCEOFF = V

CC,

T_IN = VCCor GND

nA

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

LOGIC INPUTS AND RECEIVER OUTPUTS

MAX3238E/MAX3248E

+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers

with ±15kV ESD-Protected I/O and Logic Pins

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and
C2–C4 = 0.33µF (tested at 5.0V ±10%), T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

Figure 4a

Figure 4a

Figure 4b

VCC= 5V, Figure 4b (Note 3)

VCC= 5V, Figure 4b

I

OUT

= 1.0mA

I

OUT

= -1.0mA

VCC= 5V, Figure 4b

V-0.3 0.3

Receiver Input Threshold to
INVALID Output Low

V

2.7

Receiver Input Threshold to
INVALID Output High

s15 30 60

Receiver or Transmitter Edge to
Shutdown (t

AUTOSHDN

)

µs25

Receiver or Transmitter Edge to
Transmitters Enabled (tWU)

µs60

Receiver Positive or Negative
Threshold to INVALID Low (t

INVL

)

V0.4

INVALID Output Voltage Low

V

V

CC -

0.6

INVALID Output Voltage High

µs0.3

Receiver Positive or Negative
Threshold to INVALID High (t

INVH

)

Positive threshold

Negative threshold -2.7

V-25 25

I

OUT

= -1.0mA

I

OUT

= 1.0mA

Input Voltage Range

VCC= 3.3V

Receivers disabled

T_IN, FORCEON, FORCEOFF (Note 2)

0.6 1.0

CONDITIONS

VCC= 5.0V

V

0.8 1.4

Input Threshold Low

VCC= 3.3V 1.5 2.4

VCC= 5.0V

V

2.0 2.4

Input Threshold High

V0.6Input Hysteresis

TA= +25°C kΩ357Input Resistance

V

V

CC

-V

CC

-

0.6 0.1

Output Voltage High

V0.4Output Voltage Low

µA±0.05 ±10Output Leakage Current

µA918Input Leakage Current

UNITSMIN TYP MAXPARAMETER

All transmitter outputs loaded with 3kΩ to ground V±5.0 ±5.4Output Voltage Swing

VCC= 0, T

OUT

= ±2V Ω300 50kOutput Resistance

VCC≤ 3.6V ±35 ±60

VCC> 3.6V

mA

±40 ±100

Output Short-Circuit Current

IEC 1000-4-2 Air-Gap Discharge Method ±15

IEC 1000-4-2 Contact Discharge Method ±8

Human Body Model

kV

±15

ESD Protection (R_IN, T_IN, R_OUT,
T_OUT, FORCEON, FORCEOFF,
INVALID, R_OUTB)

RECEIVER INPUTS

AutoShutdown (FORCEON = GND, FORCEOFF = VCC)

TRANSMITTER OUTPUTS

ESD PROTECTION

-6

-2

-4

2

0

4

6

-5

-3

1

-1

3

5

0 1000 1500500 2000 2500 3000

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3238E toc01

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

V

OUT-

V

OUT

+

FOR DATA RATES UP TO 250kbps
1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ + C

L

0

4

2

8

6

10

12

0 1000 1500500 2000 2500 3000

SLEW RATE vs. LOAD CAPACITANCE

MAX3238E toc02

LOAD CAPACITANCE (pF)

SLEW RATE (V/µs)

SR+

SR-

1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ + C

L

50

20

10

0

0 1000500 2000 3000

SUPPLY CURRENT vs. LOAD CAPACITANCE

WHEN TRANSMITTING DATA

30

MAX3238 TOC-03

SUPPLY CURRENT (mA)

LOAD CAPACITANCE (pF)

1500 2500

40

250kbps

20kbps

120kbps

1 TRANSMITTER 20kbps, 120 kbps, 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ + C

L

__________________________________________Typical Operating Characteristics

(VCC= +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, TA= +25°C, unless otherwise noted.)

MAX3238E/MAX3248E

+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and
C2–C4 = 0.33µF (tested at 5.0V ±10%), T

A

= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +25°C.)

Note 2: The transmitter inputs have an active positive feedback resistor. The input current goes to zero when the inputs are at the

supply rails.

Note 3: During AutoShutdown only, a transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic

wake-up thresholds.

CONDITIONS UNITSMIN TYP MAXPARAMETER

| t

PHL

- t

PLH

|

430

t

PHL

R_IN to R_OUT,
CL= 150pF

t

PLH

CL= 150pF to 1000pF

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

CL= 150pF to 2500pF

0.15

VCC= 3.3V,
T

A

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

-3V or -3V to +3V

Normal operation

Normal operation

| t

PHL

- t

PLH

|

µs

0.15

Receiver Propagation Delay

kbps250Maximum Data Rate

V/µs

630

Transition-Region Slew Rate

µs2.6Receiver Output Enable Time

µs2.4Receiver Output Disable Time

ns50

ns50Receiver Skew

Transmitter Skew

TIMING CHARACTERISTICS

MAX3238E/MAX3248E

+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers

with ±15kV ESD-Protected I/O and Logic Pins

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(VCC= +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, TA= +25°C, unless otherwise noted.)

______________________________________________________________Pin Description

Output of the Valid Signal Detector. A logic 1 indicates if a valid RS-232 level is present on
receiver inputs.

INVALID

15

Noninverting Complementary Receiver Output. Always active.R1OUTB16

TTL/CMOS Transmitter Inputs (T5IN–T1IN). This pin has an active positive feedback resis­tor. Once driven to a valid logic level, the pin retains that level if left unconnected until
power is cycled.

T_IN17, 19, 22, 23, 24

TTL/CMOS Receiver Outputs (R3OUT–R1OUT)R_OUT18, 20, 21

Negative Terminal of Voltage-Doubler Charge-Pump CapacitorC1-25

RS-232 Transmitter Outputs (T1OUT–T5OUT)T_OUT5, 6, 7, 10, 12

RS-232 Receiver Inputs (R1IN–R3IN)R_IN8, 9, 11

Force-On Input. Drive high to override AutoShutdown Plus, keeping transmitters and
receivers on (FORCEOFF must be high) (Table 1). This pin has an active positive feedback
resistor. Once driven to a valid logic level, the pin retains that level if left unconnected until
power is cycled.

FORCEON13

Force-Off Input. Drive low to shut down transmitters, receivers (except R1OUTB), and on­board supply. This overrides AutoShutdown Plus and FORCEON (Table 1). This pin has an
active positive feedback resistor. Once driven to a valid logic level, the pin retains that
level if left unconnected until power is cycled.

FORCEOFF

14

-5.5V Generated by the Charge PumpV-4

Negative Terminal of Inverting Charge-Pump CapacitorC2-3

PIN

GroundGND2

Positive Terminal of Inverting Charge-Pump CapacitorC2+

1

FUNCTIONNAME

26 V

CC

+3.0V to +5.5V Supply Voltage

27 V+ +5.5V Generated by the Charge Pump

28 C1+ Positive Terminal of Voltage-Doubler Charge-Pump Capacitor

TRANSMITTER OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE

6
5
4
3
2

1 TRANSMITTER 250kbps

1

4 TRANSMITTERS 15.6kbps

0

ALL TRANSMITTERS LOADED

-1

WITH 3kΩ +1000pF

-2

-3

-4

TRANSMITTER OUTPUT VOLTAGE (V)

-5

-6

2.0 3.0 3.52.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)

V

+

OUT

V

MAX3238E toc04

OUT-

50

40

30

20

SUPPLY CURRENT (mA)

10

0

2.0 3.0 3.52.5 4.0 4.5 5.0

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ +1000pF

SUPPLY VOLTAGE (V)

MAX3238E toc05