Datasheet MAX3230E, MAX3230AE, MAX3231E, MAX3231AE Datasheet (MAXIM)

General Description

The MAX3230E/AE and MAX3231E/AE are +2.5V to
+5.5V powered EIA/TIA-232 and V.28/V.24 communica­tions interfaces with low power requirements, high data­rate capabilities, and enhanced electrostatic discharge
(ESD) protection, in a chip-scale package (UCSP™)
and WLP package. All transmitter outputs and receiver
inputs are protected to ±15kV using IEC 1000-4-2 Air­Gap Discharge, ±8kV using IEC 1000-4-2 Contact
Discharge, and ±15kV using the Human Body Model.

The MAX3230E/AE and MAX3231E/AE achieve a 1µA
supply current with Maxim’s AutoShutdown™ feature.
They save power without changing the existing BIOS or
operating systems 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 RS-232-compliant perfor­mance from a +3.1V to +5.5V supply, and RS-232­compatible performance with a supply voltage as low
as +2.5V. The dual charge pump requires only four,
small 0.1µF capacitors for operation from a +3.0V sup­ply. Each device is guaranteed to run at data rates of
250kbps while maintaining RS-232 output levels.

The MAX3230E/AE and MAX3231E/AE offer a separate
power-supply input for the logic interface, allowing con­figurable logic levels on the receiver outputs and trans­mitter inputs. Operating over a +1.65V to V

CC

range, V

L

provides the MAX3230E/AE and MAX3231E/AE com­patibility with multiple logic families.

The MAX3231E/AE contains one receiver and one trans­mitter. The MAX3230E/AE contains two receivers and two
transmitters. The MAX3230E/AE and MAX3231E/AE are
available in tiny chip-scale and WLP packaging and are
specified across the extended industrial (-40°C to +85°C)
temperature range.

Applications

Personal Digital Assistants

Cell-Phone Data Lump Cables

Set-Top Boxes

Handheld Devices

Cell Phones

Features

♦ 6 x 5 Chip-Scale Package (UCSP) and WLP

Package

♦ ESD Protection for RS-232 I/O Pins

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

♦ 1µA Low-Power AutoShutdown

♦ 250kbps Guaranteed Data Rate

♦ Meet EIA/TIA-232 Specifications Down to +3.1V

♦ RS-232 Compatible to +2.5V Allows Operation

from Single Li+ Cell

♦ Small 0.1µF Capacitors

♦ Configurable Logic Levels

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

________________________________________________________________

Maxim Integrated Products

1

Typical Operating Circuits

19-3250; Rev 1; 10/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

UCSP is a trademark of Maxim Integrated Products, Inc.

AutoShutdown is a trademark of Maxim Integrated Products, Inc.

Typical Operating Circuits continued at end of data sheet.

Pin Configurations appear at end of data sheet.

+

Denotes a lead-free/RoHS-compliant package.

T = Tape-and-reel.

PART TEMP RANGE BUMP-PACKAGE

MAX3230EEBV-T -40°C to +85°C 6 x 5 UCSP

MAX3230AEEWV+-T -40°C to +85°C 6 x 5 WLP

MAX3231EEBV-T -40°C to +85°C 6 x 5 UCSP

MAX3231AEEWV+-T -40°C to +85°C 6 x 5 WLP

C

BYPASS

C1

0.1μF

C2

0.1μF

TTL/CMOS

INPUTS

TTL/CMOS

OUTPUTS

2.5V TO 5.5V

1.65V TO 5.5V

0.1μF

0.1μF

C1

D1

A2

A3

A6

B6

D6

C6

B5

C1+

C1-

C2+

C2-

T1IN

T2IN

R1OUT

R2OUT

A1 A5

V

CC

MAX3230E/AE

V

L

V

L

V

L

V

L

GND

E1

V

B1

L

V+

A4

V-

T1OUT

E3

T2OUT

E4

R1IN

E6

5kΩ

R2IN

E5

5kΩ

E2

INVALID

C5

FORCEOFFFORCEON

C3

0.1μF

C4

0.1μF

RS-232
OUTPUTS

RS-232
INPUTS

TO POWER­MANAGEMENT
UNIT

V

L

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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 +6.0V

V+ to GND .............................................................-0.3V to +7.0V

V- to GND ..............................................................+0.3V to -7.0V

V+ to |V-| (Note 1) ................................................................+13V

V

L

to GND..............................................................-0.3V to +6.0V

Input Voltages

T_IN_, FORCEON, FORCEOFF to GND.....-0.3V to (V

L

+ 0.3V)

R_IN_ to GND ...................................................................±25V

Output Voltages

T

_OUT to GND ...............................................................±13.2V

R

_OUT INVALID to GND ............................-0.3V to (V

L

+ 0.3V)

INVALID to GND.........................................-0.3V to (V

CC

+ 0.3V)

Short-Circuit Duration T

_

OUT to GND........................Continuous

Continuous Power Dissipation (T

A

= +70°C)

6

✕ 5 UCSP (derate 10.1mW/°C above +70°C) ...........805mW

6

✕ 5 WLP (derate 20mW/°C above +70°C).....................1.6W

Operating Temperature Range ...........................-40°C to +85°C

Junction Temperature......................................................+150°C

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

Bump Temperature (soldering)

Infrared (15s) ...............................................................+200°C

Vapor Phase (20s) .......................................................+215°C

ELECTRICAL CHARACTERISTICS

(VCC= +2.5V to +5.5V, VL= +1.65V to +5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%, TA= T

MIN

to T

MAX

. Typical values are at TA=

+25°C, unless otherwise noted.) (Note 2)

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

DC CHARACTERISTICS

VL Input Voltage Range V

VCC Supply Current,
AutoShutdown

V
AutoShutdown Disabled

VL Supply Current T_IN, I

LOGIC INPUTS

Input-Logic Low T_IN, FORCEON, FORCEOFF 0.4 V
Input-Logic High T_IN, FORCEON, FORCEOFF 0.66 ✕ V

Transmitter Input Hysteresis 0.5 V
Input Leakage Current T_IN, FORCEON, FORCEOFF ±0.01 ±1 µA

RECEIVER OUTPUTS

Output Leakage Currents

Output-Voltage Low I

Output-Voltage High I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

L

FORCEON = GND

Supply Current,

CC

I

I

CC

CC

FORCEOFF = V
FORCEOFF = GND 10

FORCEON, FORCEOFF = V

FORCEON = FORCEOFF = VL, no load 0.3 1 mA

FORCEON or FORCEOFF = GND or VL,

L

V

= VL = +5V, no receivers switching

CC

R_OUT, receivers disabled, FORCEOFF =
GND or in AutoShutdown

= 0.8mA 0.4 V

OUT

= -0.5mA VL - 0.4 VL - 0.1 V

OUT

, all RIN open

L

L

1.65 VCC + 0.3 V

10

1mA

1µA

L

±10 µA

µA

V

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +2.5V to +5.5V, VL= +1.65V to +5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%, TA= T

MIN

to T

MAX

. Typical values are at TA=

+25°C, unless otherwise noted.) (Note 2)

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

_______________________________________________________________________________________ 3

RECEIVER INPUTS

Input Voltage Range -25 +25 V

Input-Threshold Low TA = +25°C

Input-Threshold High TA = +25°C

Input Hysteresis 0.5 V

Input Resistance 357kΩ

AUTOMATIC SHUTDOWN

Receiver Input Threshold to
INVALID Output High

Receiver Input Threshold to
INVALID Output Low

Receiver Positive or Negative
Threshold to INVALID High

Receiver Positive or Negative
Threshold to INVALID Low

Receiver Edge to Transmitters
Enabled

INVALID OUTPUT

Output-Voltage Low I

Output-Voltage High I

TRANSMITTER OUTPUTS

VCC Mode Switch Point
(V

VCC Mode Switch Point
(V

V

Output Voltage Swing

Output Resistance VCC = V+ = V- = 0, T_OUT = ±2V 300 10M Ω

Output Short-Circuit Current ±60 mA

Output Leakage Current T_OUT = ±12V, transmitters disabled ±25 µA

ESD PROTECTION

R_IN, T_OUT

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

VCC = +3.3V 0.6 1.2

= +5.0V 0.8 1.7

V

CC

VCC = +3.3V 1.3 2.4

= +5.0V 1.8 2.4

V

CC

Figure 3a

t

INVH

t

INVL

t

WU

Falling)

CC

Rising)

CC

M od e S w i tch- P oi nt H yster esi s 400 mV

C C

VCC = +5.0V, Figure 3b 1 µs

VCC = +5.0V, Figure 3b 30 µs

VCC = +5.0V, Figure 3b 100 µs

= 0.8mA 0.4 V

OUT

= -0.5mA VCC - 0.4 VCC - 0.1 V

OUT

T_OUT = ±5.0V to ±3.7V 2.85 3.10 V

T_OUT = ±3.7V to ±5.0V 3.3 3.7 V

All transmitter
outputs loaded
with 3kΩ to
ground

Human Body Model ±15

IEC 1000-4-2 Air-Gap Discharge ±15

IEC 1000-4-2 Contact Discharge ±8

Positive threshold 2.7

Negative threshold -2.7

VCC = +3.1V to +5.5V,
V

falling, TA = +25°C

CC

= +2.5V to +3.1V,

V

CC

V

rising

CC

-0.3 +0.3 V

±3.7

±5 ±5.4

V

V

V

V

kV

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

4 _______________________________________________________________________________________

Note 2: VCCmust be greater than VL.

TIMING CHARACTERISTICS

(VCC= +2.5V to +5.5V, VL= +1.65V to +5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%, TA= T

MIN

to T

MAX

. Typical values are at TA=

+25°C, unless otherwise noted.) (Note 2)

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

-2

-4

2

0

4

6

0 1500 2000500 1000 2500 3000

TRANSMITTER OUTPUT VOLTAGE

vs. LOAD CAPACITANCE

MAX3230E/30AE/31E/31AE toc01

LOAD CAPACITANCE (pF)

TRANSMITTER OUTPUT VOLTAGE (V)

V

OH

V

OL

VCC RISING

0

10

5

20

15

25

30

0 2500 3000

SLEW RATE vs. LOAD CAPACITANCE

MAX3230E/30AE/31E/31AE toc02

LOAD CAPACITANCE (pF)

SLEW RATE (V/μs)

1000500 1500 2000

VCC = 5.5V

VCC = 2.5V

0

6

4

2

8

10

12

14

16

18

20

0 1000500 1500 2000 2500 3000

OPERATING SUPPLY CURRENT

vs. LOAD CAPACITANCE (MAX3231E)

MAX3230E/30AE/31E/31AE toc03

LOAD CAPACITANCE (pF)

OPERATING SUPPLY CURRENT (mA)

250kbps

20kbps

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

R

= 3kΩ, CL = 1000pF, one transmitter

Maximum Data Rate

Receiver Propagation Delay

L

switching

Receiver input to receiver output,
C

= 150pF

L

Receiver-Output Enable Time VCC = VL = +5V 200 ns

Receiver-Output Disable Time VCC = VL = +5V 200 ns

Transmitter Skew | t

Receiver Skew | t

Transition-Region Slew Rate

PHL

PHL

- t

| 100 ns

PLH

- t

|50ns

PLH

R

= 3kΩ to 7kΩ, CL = 150pF to

L

1000pF, T

= +25°C

A

250 kbps

0.15 µs

6 30 V/µs

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

_______________________________________________________________________________________ 5

Pin Description

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.)

0

6

4

2

8

10

12

14

16

18

20

2.5 3.53.0 4.0 4.5 5.0 5.5

OPERATING SUPPLY CURRENT

vs. SUPPLY VOLTAGE (MAX3231E)

MAX3230E/30AE/31E/31AE toc04

SUPPLY VOLTAGE (V)

OPERATING SUPPLY CURRENT (mA)

-8

-4

-6

2

0

-2

8

6

4

10

2.5 3.53.0 4.0 4.5 5.0 5.5

TRANSMITTER OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE (V

CC

RISING)

MAX3230E/30AE/31E/31AE toc05

SUPPLY VOLTAGE (V)

TRANSMITTER OUTPUT VOLTAGE (V)

V

OH

V

OL

-8

-4

-6

2

0

-2

8

6

4

10

2.5 3.53.0 4.0 4.5 5.0 5.5

TRANSMITTER OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE (V

CC

FALLING)

MAX3230E/30AE/31E/31AE toc06

SUPPLY VOLTAGE (V)

TRANSMITTER OUTPUT VOLTAGE (V)

V

OH

V

OL

BUMP

MAX3230E/

MAX3230AE

A1 A1 V

A2 A2 C2+ Inverting Charge-Pump Capacitor Positive Terminal

A3 A3 C2- Inverting Charge-Pump Capacitor Negative Terminal

A4 A4 V- Negative Charge-Pump Output. -5.5V/-4.0V generated by charge pump.

A5 A5 V

A6, B6 A6 T_IN Transmitter Input(s)

B1 B1 V+

B2, B3, B4,
C2, C3, C4,

D2–D5

B5 B5 FORCEON

C1 C1 C1+ Positive Regulated Charge-Pump Capacitor Positive Terminal

C5 C5 FORCEOFF

MAX3231E/

MAX3231AE

B2, B3, B4,

C2, C3, C4,

D2–D5

NAME FUNCTION

CC

L

Supply Voltage. +2.5V to +5.5V supply voltage.

Logic Voltage Input. Logic-level input for receiver outputs and transmitter inputs.
Connect VL to the system-logic supply voltage or VCC if no logic supply is required.

Positive Charge-Pump Output. +5.5V/+4.0V generated by charge pump. If charge
pump is generating +4.0V, the device has switched from RS-232-compliant to RS-232­compatible mode.

No Connection. The MAX3230E/MAX3231E are not populated with solder bumps at

N.C.

these locations. The MAX3230AE/MAX3231AE are populated with electrically isolated
solder bumps at these locations.

Active High FORCEON Input. Drive FORCEON high to override automatic circuitry,
keeping transmitters and charge pumps on.

Active-Low FORCEOFF Input. Drive FORCEOFF low to shut down transmitters,
receivers, and on-board charge pump. This overrides all automatic circuitry and
FORCEON.

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

6 _______________________________________________________________________________________

Detailed Description

Dual Mode™ Regulated Charge-Pump

Voltage Converter

The MAX3230E/AE and MAX3231E/AE internal power
supply consists of a dual-mode regulated charge
pump. For supply voltages above +3.7V, the charge
pump generates +5.5V at V+ and -5.5V at V-. 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.

For supply voltages below +2.85V, the charge pump
generates +4.0V at V+ and -4.0V at V-. The charge
pumps operate in a discontinuous mode. If the output
voltages are less than ±4.0V, the charge pumps are
enabled. If the output voltages exceed ±4.0V, 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- supply voltages.

Voltage Generation in the

Switchover Region

The MAX3230E/AE and MAX3231E/AE include a
switchover circuit between these two modes that have
approximately 400mV of hysteresis around the
switchover point. The hysteresis is shown in Figure 1.
This large hysteresis eliminates mode changes due to
power-supply bounce.

For example, a three-cell NiMh battery system starts at
V

CC

= +3.6V, and the charge pump generates an out­put voltage of ±5.5V. As the battery discharges, the
MAX3230E/AE and MAX3231E/AE maintain the outputs

in regulation until the battery voltage drops below +3.1V.
The output regulation points then change to ±4.0V.

When VCCis rising, the charge pump generates an out­put voltage of ±4.0V, while VCCis between +2.5V and
+3.5V. When VCCrises above the switchover voltage of
+3.5V, the charge pump switches modes to generate
an output of ±5.5V.

Table 1 shows different supply schemes and their oper­ating voltage ranges.

RS-232 Transmitters

The transmitters are inverting level translators that
convert CMOS logic levels to RS-232 levels. The
MAX3230E/AE and MAX3231E/AE automatically reduce
the RS-232-compliant levels (±5.5V) to RS-232-compat­ible levels (±4.0V) when V

CC

falls below approximately
+3.1V. The reduced levels also reduce supply-current
requirements, extending battery life. Built-in hysteresis
of approximately 400mV for VCCensures that the RS-

Figure 1. V+ Switchover for Changing V

CC

Dual Mode is a trademark of Maxim Integrated Products, Inc.

BUMP

MAX3230E/

MAX3230AE

NAME FUNCTION

C6, D6 C6 R_OUT Receiver Output(s)

D1 D1 C1- Positive Regulated Charge-Pump Capacitor Negative Terminal

E1 E1 GND Ground

E2 E2 INVALID

Valid Signal-Detector Output. Output INVALID is enabled low if no valid RS-232 level is
present on any receiver input.

E3, E4 E3 T_OUT RS-232 Transmitter Output(s)

E5, E6 E5 R_IN RS-232 Receiver Input(s)

—

B6, D6, E4,

E6

N.C.

No Connection. These locations are populated with solder bumps, but are electrically
isolated.

Pin Description (continued)

MAX3231E/

MAX3231AE

V

CC

V+

20ms/div

4V

0

6V

0

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

232 output levels do not change if VCCis noisy or has a
sudden current draw causing the supply voltage to drop
slightly. The outputs return to RS-232-compliant levels
(±5.5V) when VCCrises above approximately +3.5V.

The MAX3230E/AE and MAX3231E/AE transmitters
guarantee a 250kbps data rate with worst-case loads of
3kΩ in parallel with 1000pF.

When FORCEOFF is driven to ground, the transmitters
and receivers are disabled and the outputs become
high impedance. When the AutoShutdown circuitry
senses that all receiver and transmitter inputs are inac­tive for more than 30µs, the transmitters are disabled
and the outputs go to a high-impedance state. When
the power is off, the MAX3230E/AE and MAX3231E/AE
permit the transmitter outputs to be driven up to ±12V.

The transmitter inputs do not have pullup resistors.
Connect unused inputs to GND or VL.

RS-232 Receivers

The MAX3230E/AE and MAX3231E/AE receivers con­vert RS-232 signals to logic-output levels. All receivers
have inverting tri-state outputs and can be active or
inactive. In shutdown (FORCEOFF = low) or in
AutoShutdown, the MAX3230E/AE and MAX3231E/AE
receivers are in a high-impedance state (Table 2).

The MAX3230E/AE and MAX3231E/AE feature an
INVALID output that is enabled low when no valid RS-232

signal levels have been detected on any receiver inputs.
INVALID is functional in any mode (Figures 2 and 3).

AutoShutdown

The MAX3230E/AE and MAX3231E/AE achieve a 1µA
supply current with Maxim’s 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 on-board charge
pump and drivers are shut off, reducing VCCsupply
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 2c summarize the MAX3230E/AE
and MAX3231E/AE 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
2a, 2b, and 3a depict valid and invalid RS-232-receiver
levels. Figures 3a and 3b show the input levels and tim­ing diagram for AutoShutdown operation.

A system with AutoShutdown can require 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 MAX3230E/AE and

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

_______________________________________________________________________________________ 7

Table 1. Operating Supply Options

Table 2. Output Control Truth Table

X = Don’t care.
† = INVALID output state is determined by R_IN input levels.

SYSTEM SUPPLY (V) VCC (V) VL (V) RS-232 MODE

1 Li+ Cell +2.4 to +4.2 Regulated system voltage Compliant/Compatible

3 NiCad/NiMh Cells +2.4 to +3.8 Regulated system voltage Compliant/Compatible

Regulated Voltage Only

(V

falling)

CC

Regulated Voltage Only

(V

falling)

CC

+3.0 to +5.5 +3.0 to +5.5 Compliant

+2.5 to +3.0 +2.5 to +3.0 Compatible

TRANSCEIVER STATUS FORCEON FORCEOFF RECEIVER STATUS INVALID

Shutdown (AutoShutdown) Low High High impedance Low

Shutdown (Forced Off) X Low High impedance †

Normal Operation (Forced On) High High Active †

Normal Operation (AutoShutdown) Low High Active High

MAX3231E/AE are active. If the other system transmits
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 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 3b).

VLLogic Supply Input

Unlike other RS-232 interface devices, where the receiv­er outputs swing between 0 and VCC, the MAX3230E/AE
and MAX3231E/AE feature a separate logic supply input
(VL) that sets VOHfor the receiver outputs. The transmit­ter inputs (T_IN), FORCEON, and FORCEOFF, are also
referred to VL. This feature allows maximum flexibility in
interfacing to different systems and logic levels.
Connect VLto the system’s logic supply voltage (+1.65V
to +5.5V), and bypass it with a 0.1µF capacitor to GND.
If the logic supply is the same as VCC, connect VLto
VCC. Always enable VCCbefore enabling the VLsupply.
VCCmust be greater than or equal to the VLsupply.

Software-Controlled Shutdown

If direct software control is desired, connect FORCEOFF
and FORCEON together to disable AutoShutdown. The

microcontroller (µC) then drives FORCEOFF and
FORCEON like a SHDN input. INVALID can be used to
alert the µC to indicate serial data activity.

±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
MAX3230E/AE and MAX3231E/AE 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 power-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.

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 IEC 1000-4-2

3) ±15kV using the IEC 1000-4-2 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 5a shows the Human Body Model. Figure 5b
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,

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

8 _______________________________________________________________________________________

Figure 2a. MAX323_E Entering 1µA Supply Mode with
AutoShutdown

Figure 2b. MAX323_E with Transmitters Enabled Using
AutoShutdown

Figure 2c. MAX323_E AutoShutdown Logic

+0.3V

TO MAX323 _E

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.

+2.7V

R_IN

-2.7V

30μs

COUNTER

30μs

COUNTER

POWER SUPPLY

AND TRANSMITTERS

INVALID

R

POWER SUPPLY

INVALID

R

TO MAX323 _E

V

CC

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.

FORCEOFF

FORCEON

INVALID

POWER DOWN

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.

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

which is then discharged into the test device through a

1.5kΩ resistor.

IEC 1000-4-2

The IEC 1000-4-2 standard covers ESD testing and per­formance of finished equipment. It does not specifically
refer to ICs. The MAX3230E/AE and MAX3231E/AE aid
in designing equipment that meets Level 4 (the highest
level) of IEC 1000-4-2, without the need for additional
ESD-protection components.

The major difference between tests done using the
Human Body Model and IEC 1000-4-2 is a higher peak
current in IEC 1000-4-2, because series resistance is
lower in the IEC 1000-4-2 model. Hence, the ESD with­stands voltage measured to IEC 1000-4-2 and is gener­ally lower than that measured using the Human Body
Model. Figure 6a shows the IEC 1000-4-2 model, and
Figure 6b shows the current waveform for the ±8kV IEC
1000-4-2 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 can be used. However, ceramic chip capaci­tors with an X7R or X5R dielectric work best. The charge
pump requires 0.1µF capacitors for 3.3V operation. For
other supply voltages, see 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 the vaue of C1.

Caution: 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

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

_______________________________________________________________________________________ 9

Figure 3. AutoShutdown Trip Levels

Figure 4. AutoShutdown with Initial Turn-On to Wake Up a

Mouse or Another System

+2.7V

+0.3V

0

-0.3V

RECEIVER INPUT LEVELS

-2.7V

a)

RECEIVER

INPUT

VOLTAGE

(V)

V

CC

INVALID

OUTPUT

(V)

0

V+

V

CC

0

V-

TRANSMITTERS ENABLED, INVALID HIGH

INDETERMINATE

AutoShutdown, TRANSMITTERS DISABLED,

1μA SUPPLY CURRENT, INVALID LOW

INDETERMINATE

TRANSMITTERS ENABLED, INVALID HIGH

t

INVL

t

INVH

INVALID
REGION

t

WU

b)

POWER-

MANAGEMENT

UNIT

MASTER SHDN LINE

0.1μF1MΩ

FORCEOFF

FORCEON

MAX3230E/AE
MAX3231E/AE

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

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 power-

supply 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 7 shows a transmitter output when exiting shut­down mode. The transmitter is loaded with 3kΩ in par­allel with 1000pF. The transmitter output displays no
ringing or undesirable transients as it comes out of
shutdown, and is enabled only when the magnitude of
V- exceeds approximately -3V.

High Data Rates

The MAX3230E/AE and MAX3231E/AE 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
250kbps. For Figure 9, the transmitter was driven at
120kbps into an RS-232 load in parallel with 1000pF.
For Figure 10, a single transmitter was driven at
250kbps and loaded with an RS-232 receiver in paral­lel with 1000pF.

Figure 6a. IEC 1000-4-2 ESD Test Model

Figure 6b. IEC 1000-4-2 ESD Generator Current Waveform

Table 3. Required Capacitor Values

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

10 ______________________________________________________________________________________

Figure 5a. Human Body ESD Test Models

Figure 5b. Human Body Model Current Waveform

1MΩ RD 1500Ω

R

C

DISCHARGE

RESISTANCE

STORAGE

s

CAPACITOR

HIGH-

VOLTAGE

DC

SOURCE

CHARGE-CURRENT-

LIMIT RESISTOR

C

100pF

AMPERES

IP 100%

90%

36.8%

10%

0

0

t

RL

I

r

TIME

t

DL

CURRENT WAVEFORM

DEVICE

UNDER

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

TEST

I

100%

90%

PEAK

I

10%

tr = 0.7ns to 1ns

30ns

60ns

t

VCC (V) C1, C

BYPASS

2.5 to 3.0 0.22 0.22

3.0 to 3.6 0.1 0.1

4.5 to 5.5 0.047 0.33

3.0 to 5.5 0.22 1

(µF) C2, C3, C4 (µF)

50MΩ TO 100MΩ RD 330Ω

HIGH-

VOLTAGE

DC

SOURCE

R

C

CHARGE-CURRENT-

LIMIT RESISTOR

C

150pF

DISCHARGE

RESISTANCE

STORAGE

s

CAPACITOR

DEVICE

UNDER

TEST

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

UCSP Applications Information

For the latest application details on UCSP construction,
dimensions, tape carrier information, PC board tech­niques, bump-pad layout, and recommended reflow
temperature profile, as well as the latest information on
reliability testing results, refer to the Application Note

UCSP—A Wafer-Level Chip-Scale Package

available

on Maxim’s website at www.maxim-ic.com/ucsp.

Chip Information

TRANSISTOR COUNT: 698

PROCESS: CMOS

Figure 8. Transmitter Loopback Test Circuit

Figure 9. Loopback Test Result at 120kbps

Figure 10. Loopback Test Result at 250kbps

Figure 7. Transmitter Outputs Exiting Shutdown or Powering Up

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

______________________________________________________________________________________ 11

FORCEON =

FORCEOFF

T_OUT

4μs/div

5V/div

0

2V/div

0

0.1μF

V

V

C1+

C1

C1-

MAX3231E/AE

C2+

C2

C2-

T1IN

R1OUT

V

CC

L

0.1μF

V

CC

L

V+

V-

V

L

T1OUT

V

L

R1IN

C3

C4

1000pF

T_IN

T_OUT

R_OUT

4μs/div

T_IN

T_OUT

R_OUT

4μs/div

5V

0

5V

0

-5V

5V

0

5V

0

5V

0

-5V

5V

0

5kΩ

TO POWER­MANAGEMENT UNIT

V

L

GND

INVALID

FORCEOFFFORCEON

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

12 ______________________________________________________________________________________

Typical Operating Circuits

(continued)

C

BYPASS

0.1μF

0.1μF

TTL/CMOS

2.5V TO 5.5V

0.1μF

C1

C1

C2

C1+

D1

C1-

A2

C2+

A3

C2-

T1IN

A6

C6

R1OUT

1.65V TO 5.5V

A1 A5

V

CC

MAX3231E/AE

V

L

V

L

V

L

T1OUT

R1IN

5kΩ

INVALID

0.1μF

B1

V+

V-

A4

E3

E5

E2

C3

0.1μF

C4

0.1μF

RS-232

TO POWER­MANAGEMENT
UNIT

B5

FORCEOFFFORCEON

GND

E1

C5

V

L

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

V

CC

12 3456

C2+ C2-

FON = FORCEON
FOFF = FORCEOFF
INV = INVALID

V

L

T1IN

V+ N.C. N.C.

FONN.C. T2IN

N.C.C1+ N.C.

FOFFN.C. R2OUT

C1- N.C. N.C.

N.C.

N.C.

R1OUT

GND

INV

T1OUT T2OUT

R2IN

A

B

C

D

E R1IN

V-

MAX3230E/AE

TOP VIEW

Pin Configurations

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

______________________________________________________________________________________ 13

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

14 ______________________________________________________________________________________

Pin Configurations (continued)

TOP VIEW

A

B

C

D

E N.C.

V

CC

V+ N.C. N.C.

C1- N.C. N.C.

GND

12 3456

C2+ C2-

N.C.C1+ N.C.

INV

T1OUT N.C.

MAX3231E/AE

V-

N.C.

V

L

FONN.C. N.C.

FOFFN.C. R1OUT

N.C.

R1IN

T1IN

N.C.

FON = FORCEON
FOFF = FORCEOFF
INV = INVALID

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V

RS-232 Transceivers in UCSP and WLP

______________________________________________________________________________________ 15

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

6 x 5 UCSP B30-3

21-0123

6 x 5 WLP W302A3-2

21-0016

Package Information

For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.

MAX3230E/MAX3230AE/MAX3231E/MAX3231AE

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP

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

© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Revision History

REVISION

NUMBER

0 5/04 Initial release —

1 10/08 Addition of lead-free and WLP packaging 1, 5, 6, 7, 15

REVISION

DATE

DESCRIPTION

PAGES

CHANGED