MAXIM MAX3228, MAX3229 User Manual

General Description

The MAX3228/MAX3229 are +2.5V to +5.5V powered
EIA/TIA-232 and V.28/V.24 communications interfaces
with low power requirements, and high data-rate capa­bilities, in a chip-scale package (UCSP™).

The MAX3228/MAX3229 achieve a 1µA supply current
with Maxim’s AutoShutdown™ feature. They save
power without changes to 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-232
compatible 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 MAX3228/MAX3229 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 VCCrange, VLprovides the
MAX3228/MAX3229 compatibility with multiple logic
families.

The MAX3229 contains one receiver and one transmit­ter. The MAX3228 contains two receivers and two
transmitters. The MAX3228/MAX3229 are available in
tiny chip-scale packaging and are specified across the
extended industrial temperature range of -40°C to
+85°C.

Applications

Personal Digital Assistants
Cell Phone Data Lump Cables
Set-Top Boxes
Hand-Held Devices
Cell Phones

Features

♦ 6 ✕ 5 Chip-Scale Packaging (UCSP)
♦ 1µA Low-Power AutoShutdown
♦ 250kbps Guaranteed Data Rate
♦ Meets 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

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers

in UCSP

________________________________________________________________ Maxim Integrated Products 1

Typical Operating Circuits

19-2140; Rev 1; 5/04

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.

*Requires solder temperature profile described in the Absolute
Maximum Ratings section.

*UCSP reliability is integrally linked to the user’s assembly
methods, circuit board material, and environment. Refer to the
UCSP Reliabilitly Notice in the UCSP Reliability section of this
data sheet for more information.

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.

PART TEMP RANGE

MAX3228EBV -40°C to +85°C 6 x 5 UCSP*
MAX3229EBV -40°C to +85°C 6 x 5 UCSP*

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

C1

D1

A2

A3

A6

B6

D6

C6

B5

C1+

C1­C2+

C2­T1IN

T2IN

R1OUT

R2OUT

A1 A5

V

CC

MAX3228

V

V

V

L

GND

V

L

L

T1OUT

L

T2OUT

V

L

R1IN

5kΩ

V

L

5kΩ

V

L

INVALID

20µA20µA

FORCEOFFFORCEON

E1

V+

V-

R2IN

0.1µF

B1

A4

E3

E4

E6

E5

E2

C5

PIN-

PACKAGE

C3

0.1µF

C4

0.1µF

RS-232
OUTPUTS

RS-232
INPUTS

TO POWER­MANAGEMENT
UNIT

V

L

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers
in UCSP

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 (VL+ 0.3V)

R

_

IN to GND .....................................................................±25V

Output Voltages

T

_

OUT to GND...............................................................±13.2V

R

_

OUT to GND...........................................-0.3V to (VL+ 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 T

A

= +70°C)...805mW

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

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

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

Bump Temperature (Soldering) (Note 2)

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 3)

Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
Note 2: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device

can be exposed to during board level solder attach and rework. This limit permits only the use of the solder profiles recom­mended in the industry-standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and convection reflow. Pre­heating is required. Hand or wave soldering is not allowed.

DC CHARACTERISTICS

VL Input Voltage Range V

VCC Supply Current,
AutoShutdown

VCC Supply Current,
AutoShutdown Disabled

VL Supply Current I

LOGIC INPUTS

Pullup Currents FORCEON, FORCEOFF to V
Input Logic Low T_IN, FORCEON, FORCEOFF 0.4 V
Input Logic High T_IN, FORCEON, FORCEOFF 0.66 x V
Transmitter Input Hysteresis 0.5 V
Input Leakage Current T_IN ±0.01 ±1 µA

RECEIVER OUTPUTS

Output Leakage Currents

Output Voltage Low I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

L

FORCEON = GND

I

I

CC

CC

FORCEOFF = V
FORCEOFF = GND 10 µA

FORCEON, FORCEOFF floating 1 mA
FORCEON = FORCEOFF = V

no load
FORCEON or FORCEOFF = GND, VCC =

V

= +5v

L

L

FORCEON, FORCEOFF floating 1

R_OUT, receivers disabled, FORCEOFF =
GND or in AutoShutdown

= 0.8mA 0.4 V

OUT

, all RIN open

L

L

L

1.65 VCC + 0.3 V

20 µA

L

10 µA

0.3 1 mA

85

±10 µA

µA

V

Output Voltage High I

= -0.5mA VL - 0.4 VL - 0.1 V

OUT

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers

in UCSP

_______________________________________________________________________________________ 3

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 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

AUTOSHUTDOWN

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

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

INVALID OUTPUT

Output Voltage Low I
Output Voltage High I

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

T_OUT = ±5.0V to ±3.7V 2.85 3.1 V

T_OUT = ±3.7V to ±5.0V 3.3 3.7 V

All transmitter
outputs loaded with
3kΩ to ground.

= 0.8mA 0.4 V

OUT

= -0.5mA V

OUT

Positive threshold 2.7
Negative threshold -2.7

VCC = +3.1V to
+5.5V, V
T

= +25°C

A

V

CC

+3.1V, V

falling,

CC

= +2.5V to

rising

CC

-0.3 0.3 V

±3.7

C C

±5 ±5.4

- 0.4 V

- 0.1 V

C C

V

V

V

V

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers
in UCSP

4 _______________________________________________________________________________________

Note 3: 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 3)

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

MAX3228/9 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

MAX3228/9 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 (MAX3229)

MAX3228/9 toc03

LOAD CAPACITANCE (pF)

OPERATING SUPPLY CURRENT (mA)

250kbps

20kbps

Maximum Data Rate

Receiver Propagation Delay

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

R

= 3kΩ, CL = 1000pF, one transmitter

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

630V/µs

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers

in UCSP

_______________________________________________________________________________________ 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 (MAX3229)

MAX3228/9 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)

MAX3228/9 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)

MAX3228/9 toc06

SUPPLY VOLTAGE (V)

TRANSMITTER OUTPUT VOLTAGE (V)

V

OH

V

OL

PIN

MAX3228 MAX3229

A1 A1 V
A2 A2 C2+ Positive Terminal of Inverting Charge-Pump Capacitor
A3 A3 C2- Negative Terminal of Inverting Charge-Pump Capacitor
A4 A4 V- -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, D3, D4,

D5

B5 B5 FORCEON

—

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

NAME FUNCTION

CC

L

B2, B3, B4,
C2, C3, C4,
D2, D3, D4,

N.C. No Connection. These locations are not populated with solder bumps.

D5

B6, D6,

E4, E6

N.C.

+2.5V to +5.5V Supply Voltage

Logic-Level Input for Receiver Outputs and Transmitter Inputs. Connect VL to the

system logic supply voltage or V

if no logic supply is required.

CC

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

FORCEON Input, Active-High. Drive FORCEON high to override automatic circuitry,
keeping transmitters and charge pumps on. Pulls itself high internally if not connected.

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

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers
in UCSP

6 _______________________________________________________________________________________

Detailed Description

Dual-Mode Regulated Charge-Pump

Voltage Converter

The MAX3228/MAX3229 internal power supply consists
of a dual-mode regulated charge pump. For supply
voltages above +3.7V, the charge pump will generate
+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
will generate +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 MAX3228/MAX3229 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.

Pin Description (continued)

Table 1. Operating Supply Options

Figure 1. V+ Switchover for Changing V

CC

PIN

MAX3228 MAX3229

C5 C5 FORCEOFF

C6, D6 C6 R_OUT Receiver Output(s)

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

E1 E1 GND Ground

E2 E2 INVALID

E3, E4 E3 T_OUT RS-232 Transmitter Output(s)
E5, E6 E5 R_IN RS-232 Receiver Input(s)

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

NAME FUNCTION

FORCEOFF Input, Active-Low. Drive FORCEOFF low to shut down transmitters,
receivers, and on-board charge pump. This overrides all automatic circuitry and
FORCEON. Pulls itself high internally if not connected.

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

+3.0 to +5.5 +3.0 to +5.5 Compliant

+2.5 to +3.0 +2.5 to +3.0 Compatible

V

CC

V+

20ms/div

4V

0

6V

0

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers

in UCSP

_______________________________________________________________________________________ 7

For example, a three-cell NiMh battery system starts at
VCC= +3.6V, and the charge pump will generate an
output voltage of ±5.5V. As the battery discharges, the
MAX3228/MAX3229 maintain the outputs in regulation
until the battery voltage drops below +3.1V. Then the
output regulation points change to ±4.0V

When VCCis rising, the charge pump will generate 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
MAX3228/MAX3229 will automatically reduce the RS­232 compliant levels (±5.5V) to RS-232 compatible lev­els (±4.0V) when VCCfalls below approximately +3.1V.
The reduced levels also reduce supply current require­ments, extending battery life. Built-in hysteresis of
approximately 400mV for V

CC

ensures that the RS-232

output levels do not change if V

CC

is noisy or has a
sudden current draw causing the supply voltage to
drop slightly. The outputs will return to RS-232 compli­ant levels (±5.5V) when VCCrises above approximately
+3.5V.

The MAX3228/MAX3229 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 MAX3228/MAX3229 permit the
transmitter outputs to be driven up to ±12V.

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

L

.

RS-232 Receivers

The MAX3228/MAX3229 receivers convert RS-232 sig­nals to logic output levels. All receivers have inverting
three-state outputs and can be active or inactive. In
shutdown (FORCEOFF = low) or in AutoShutdown, the
MAX3228/MAX3229 receivers are in a high-impedance
state (Table 3).

The MAX3228/MAX3229 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).

Figure 2c. MAX322_ AutoShutdown Logic

Figure 2a. MAX322_ Entering 1µA Supply Mode via
AutoShutdown

Figure 2b. MAX322_ with Transmitters Enabled Using
AutoShutdown

+0.3V

TO MAX322 _

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.

30µs

COUNTER

POWER SUPPLY

AND TRANSMITTERS

INVALID

R

+2.7V

R_IN

-2.7V

*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

R

TO MAX322 _

POWER SUPPLY

INVALID

V

L

FORCEOFF

V

L

V

CC

FORCEON

INVALID

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.

POWER DOWN

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers
in UCSP

8 _______________________________________________________________________________________

AutoShutdown

The MAX3228/MAX3229 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 3 and Figure 2c summarize the MAX3228/
MAX3229 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 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 MAX3228/MAX3229 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 devices’ 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).

FORCEON and

FORCEOFF

In case FORCEON and FORCEOFF are inaccessible,
these pins have 60Ω (typ) pullup resistors connected to
VL(Table 2). Therefore, if FORCEON and FORCEOFF
are not connected, the MAX3228 and MAX3229 will
always be active. Pulling these pins to ground will draw
current from the VLsupply. This current can be calcu­lated from the voltage supplied at VLand the 60kΩ
(typ) pullup resistor.

VLLogic Supply Input

Unlike other RS-232 interface devices, where the
receiver outputs swing between 0 and V

CC

, the

Figure 3. AutoShutdown Trip Levels

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

Table 2. Power-On Default States

TRANSMITTERS ENABLED, INVALID HIGH

+2.7V

INDETERMINATE

+0.3V

RECEIVER INPUT LEVELS

a)

RECEIVER

INPUT

VOLTAGE

(V)

V

INVALID

OUTPUT

(V)

V

b)

POWER-

MANAGEMENT

AUTOSHUTDOWN, TRANSMITTERS DISABLED,

-0.3V

-2.7V

CC

V+

CC

V-

UNIT

0

0

0

1µA SUPPLY CURRENT, INVALID LOW

INDETERMINATE

TRANSMITTERS ENABLED, INVALID HIGH

t

INVL

MASTER SHDN LINE

FORCEOFF

t

INVH

0.1µF1MΩ

FORCEON

INVALID
REGION

t

WU

MAX3228
MAX3229

PIN NAME POWER-ON DEFAULT MECHANISM

FORCEON High Internal pullup

FORCEOFF High Internal pullup

MAX3228/MAX3229 feature a separate logic supply
input (VL) that sets VOHfor the receiver and INVALID
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 then drives FORCEOFF and FORCEON
like a SHDN input, INVALID can be used to alert the
microcontroller to indicate serial data activity.

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. 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, refer to Table 4 for
required capacitor values. Do not use values smaller
than those listed in Table 4. 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).

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.

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers

in UCSP

_______________________________________________________________________________________ 9

Table 3. Output Control Truth Table

X = Don’t care.
† = I

NVALID

output state is determined by R_IN input levels.

Table 4. Required Capacitor Values

Figure 5. Transmitter Outputs Exiting Shutdown or Powering Up

TRANSCEIVER STATUS FORCEON FORCEOFF RECEIVER STATUS INVALID

Shutdown (AutoShutdown) Low High High-Z L
Shutdown (Forced Off) X Low High-Z †
Normal Operation (Forced On) High High Active †
Normal Operation (AutoShutdown) Low High Active H

FORCEON =

FORCEOFF

5V/div
0

2V/div

VCC (V) C1, C

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)

BYPASS

T

OUT

4µs/div

0

MAX3228/MAX3229

Transmitter Outputs when

Exiting Shutdown

Figure 5 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 MAX3228/MAX3229 maintain the RS-232 ±5.0V
minimum transmitter output voltage even at high data
rates. Figure 6 shows a transmitter loopback test cir-

cuit. Figure 7 shows a loopback test result at 120kbps,
and Figure 8 shows the same test at 250kbps. For
Figure 7, the transmitter was driven at 120kbps into an
RS-232 load in parallel with 1000pF. For Figure 8, a sin­gle transmitter was driven at 250kbps, and loaded with
an RS-232 receiver in parallel with 1000pF.

+2.5V to +5.5V RS-232 Transceivers
in UCSP

10 ______________________________________________________________________________________

Figure 6. Transmitter Loopback Test Circuit

Figure 7. Loopback Test Result at 120kbps

Figure 8. Loopback Test Result at 250kbps

V

CC

0.1µF 0.1µF

V

CC

C1+

C1

C2

C1­C2+

C2-

T1IN

R1OUT

MAX3229

V

L

V

L

GND

V

V

L

L

FORCEOFFFORCEON

T1OUT

R1IN

5kΩ

INVALID

V+

V-

C3

C4

TO POWER­MANAGEMENT UNIT

V

L

1000pF

T_IN

T_OUT

R_OUT

4µs/div

T_IN

T_OUT

R_OUT

5V

0

5V

0

-5V

5V

0

5V

0

5V

0

-5V

5V

0

4µs/div

UCSP Reliability

The UCSP represents a unique packaging form factor
that may not perform equally to a packaged product
through traditional mechanical reliability tests. CSP relia­bility is integrally linked to the user’s assembly methods,
circuit board material, and usage environment. The user
should closely review these areas when considering use
of a CSP package. Performance through Operating Life
Test and Moisture Resistance remains uncompromised
as it is primarily determined by the wafer-fabrication
process.

Mechanical stress performance is a greater considera­tion for a CSP package. CSPs are attached through
direct solder contact to the user’s PC board, foregoing
the inherent stress relief of a packaged product lead
frame. Solder joint contact integrity must be consid­ered. Table 5 shows the testing done to characterize
the CSP reliability performance. In conclusion, the
UCSP is capable of performing reliably through envi­ronmental stresses as indicated by the results in the
table. Additional usage data and recommendations are
detailed in the UCSP application note, which can be
found on Maxim’s website at www.maxim-ic.com.

Chip Information

TRANSISTOR COUNT: 698
PROCESS TECHNOLOGY: CMOS

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers

in UCSP

______________________________________________________________________________________ 11

Typical Operating Circuits

(continued)

Table 5. Reliability Test Data

TEST

Temperature Cycle

-35°C to +85°C,

-40°C to +100°C

CONDITIONS DURATION

150 cycles,

900 cycles

NO. OF FAILURES PER

SAMPLE SIZE

0/10,

0/200

Operating Life TA = +70°C 240hr 0/10
Moisture Resistance +20°C to +60°C, 90% RH 240hr 0/10
Low-Temperature Storage -20°C 240hr 0/10

Low-Temperature Operational -10°C 24hr 0/10

Solderability 8hr steam age — 0/15
ESD ±2000V, Human Body Model — 0/5
High-Temperature Operating

Life

2.5V TO 5.5V

T

= +150°C 168hr 0/45

J

1.65V TO 5.5V

C

BYPASS

0.1µF

0.1µF

TTL/CMOS

0.1µF 0.1µF

C1

C1

C2

C1+

D1

C1-

A2

C2+

A3

C2­T1IN

A6

C6

R1OUT

A1 A5

V

CC

MAX3229

V

L

V

L

V

L

V+

V-

T1OUT

R1IN

B1

C3

0.1µF

A4

C4

0.1µF

E3

RS-232

E5

5kΩ

V

V

L

L

INVALID

20µA20µA

B5

FORCEOFFFORCEON

GND

E1

E2

C5

TO POWER­MANAGEMENT
UNIT

V

L

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers
in UCSP

12 ______________________________________________________________________________________

Pin Configurations

TOP VIEW

A

B

C

D

E R1IN

V

CC

V+ N.C. N.C.

C1- N.C. N.C.

GND

12 3456

C2+ C2-

N.C.C1+ N.C.

INV

V-

N.C.

T1OUT T2OUT

MAX3228 FON = FORCEON

V

L

FONN.C. T2IN

FOFFN.C. R2OUT

N.C.

R2IN

T1IN

R1OUT

FOFF = FORCEOFF
INV = INVALID

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers

in UCSP

______________________________________________________________________________________ 13

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.

MAX3229 FON = FORCEON

N.C.

V-

V

L

FONN.C. N.C.

FOFFN.C. R1OUT

N.C.

R1IN

T1IN

FOFF = FORCEOFF
INV = INVALID

N.C.

MAX3228/MAX3229

+2.5V to +5.5V RS-232 Transceivers
in UCSP

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.

14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

Package Information

30L, UCSP 6x5 .EPS

PACKAGE OUTLINE, 6x5 UCSP

21-0123

1

G

1