19-1473; Rev 2; 8/04
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
________________General Description
The MAX3233E/MAX3235E are EIA/TIA-232 and V.28/V.24
communications interfaces with automatic shutdown/
wake-up 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, to ±8kV
using IEC 1000-4-2 Contact Discharge, and to ±15kV
using the Human Body Model. The MAX3233E operates
from a +3.3V supply; the MAX3235E operates from +5.0V.
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 following two conditions occur: either
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 MAX3233E/MAX3235E have internal dual charge
pumps requiring no external capacitors. Both trans-
ceivers have a proprietary low-dropout transmitter out-
put stage that enables true RS-232 performance from a
+3.0V to +3.6V supply for the MAX3233E or a +4.5V to
+5.5V supply for the MAX3235E. These devices are
guaranteed to operate up to 250kbps. Both are avail-
able in space-saving 20-pin wide SO or plastic DIP
packages.
____________________________Features
♦
ESD Protection for RS-232 I/O Pins
±15kV—Human Body Model
±8kV—IEC 1000-4-2, Contact Discharge
±15kV—IEC 1000-4-2, Air-Gap Discharge
♦
Latchup Free
♦
1µA Supply Current
♦
AutoShutdown Plus—1997 EDN Magazine
Innovation of the Year
♦
Single-Supply Operation
+3.0V to +3.6V (MAX3233E)
+4.5V to +5.5V (MAX3235E)
♦
250kbps Guaranteed Data Rate
♦
6V/µs Guaranteed Slew Rate
♦
Meets EIA/TIA-232 Specifications Down to 3.0V
(MAX3233E)
♦
Internal Charge-Pump Capacitors
MAX3233E/MAX3235E
†
Pin Configuration/
Functional Diagram
R2OUT
1
2
3
4
5
6
7
8
9
10
20
MAX3233E
MAX3235E
R2IN
INVALID
T2IN
T1IN
FORCEON
R1OUT
T1OUT
R1IN
19
18
17
16
15
14
13
12
11
T2OUT
GND
V-
C2-
C2+
C1-
C1+
V+
V+
________________________Applications
Subnotebook and Palmtop Computers
Cellular Phones
Battery-Powered Equipment
Handheld Equipment
Peripherals
Embedded Systems
CHARGE
PUMP
_______________Ordering Information
PART
MAX3233ECWP
MAX3233ECPP
MAX3233EEWP
MAX3233EEPP
TEMP RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 SO
20 Plastic DIP
20 SO
20 Plastic DIP
V
CC
FORCEOFF
Ordering Information continued at end of data sheet.
AutoShutdown Plus is a trademark of Maxim Integrated Products, Inc.
†
Co7;
SO/DIP
4,7er
pg.
Typical Operating Circuit appears at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
MAX3233E/MAX3235E
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND (MAX3233E).........................................-0.3V to +4V
V
CC
to GND (MAX3235E).........................................-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
to GND ......................-0.3V to (V
CC
+ 0.3V)
Short-Circuit Duration
T_OUT to GND ......................................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
Wide SO (derate 10mW/°C above +70°C)..................800mW
Plastic DIP (derate 11.11mW/°C above +70°C) .........889mW
Operating Temperature Ranges
MAX323_EC_P ...................................................0°C to +70°C
MAX323_EE_P ................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) (Note 2) ...................+300°C
Note 1:
V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
Note 2:
Maximum reflow temperature is +220°C.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress rating s only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +3.0V to +3.6V for MAX3233E, V
CC
= +4.5V to +5.5V for MAX3235E; T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical val-
ues are at T
A
= +25°C.)
PARAMETER
Supply Current,
AutoShutdown Plus
Supply Current, Shutdown
Supply Current,
AutoShutdown Plus Disabled
LOGIC INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
Input Logic Threshold High
Transmitter Input Hysteresis
Input Leakage Current
Output Voltage Low
Output Voltage High
RECEIVER INPUTS
Input Voltage Range
Input Threshold Low
Input Threshold High
Input Hysteresis
Input Resistance
T
A
= +25°C
3
T
A
= +25°C
T
A
= +25°C
V
CC
= 3.3V, MAX3233E
V
CC
= 5.0V, MAX3235E
V
CC
= 3.3V, MAX3233E
V
CC
= 5.0V, MAX3235E
-25
0.6
0.8
1.0
1.3
1.5
1.8
0.5
5
7
2.4
2.4
+25
V
V
V
V
kΩ
T_IN, FORCEON,
FORCEOFF
I
OUT
= 1.6mA
I
OUT
= -1.0mA
V
CC
- 0.6 V
CC
- 0.1
T_IN, FORCEON,
FORCEOFF
T_IN, FORCEON,
FORCEOFF
V
CC
= 3.3V, MAX3233E
V
CC
= 5.0V, MAX3235E
2
2.4
0.5
±0.01
±1
0.4
0.8
V
V
V
µA
V
V
SYMBOL
CONDITIONS
FORCEON = GND,
FORCEOFF
= V
CC
,
all R_IN idle, all T_IN idle
FORCEOFF
= GND
FORCEON =
FORCEOFF
= V
CC
, no load
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS
(V
CC
= 3.3V for MAX3233E, V
CC
= 5.0V for MAX3235E, T
A
= +25°C
.
)
1
1
0.3
10
10
1
µA
µA
mA
2
_______________________________________________________________________________________
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +3.6V for MAX3233E, V
CC
= +4.5V to +5.5V for MAX3235E; T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical val-
ues are at T
A
= +25°C.)
PARAMETER
TRANSMITTER OUTPUTS
Output Voltage Swing
Output Resistance
Output Short-Circuit Current
V
OUT
= ± 12V
transmitters
disabled
V
CC
= 0 or +3.0V to
3.6V (MAX3233E)
V
CC
= 0 or +4.5V to
5.5V (MAX3235E)
±15
±8
±15
Positive threshold
Negative threshold
-2.7
-0.3
0.3
0.4
V
CC
- 0.6
1
MAX3233E
MAX3235E
70
50
100
15
30
60
2.7
kV
All transmitter outputs loaded with 3kΩ to
ground
V
CC
= V+ = V- = 0, transmitter outputs = ±2V
±5
300
±5.4
10M
±60
±25
µA
±25
V
Ω
mA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX3233E/MAX3235E
Output Leakage Current
ESD PROTECTION
IEC1000-4-2 Air Discharge
R_IN, T_OUT
IEC1000-4-2 Contact Discharge
Human Body Model
AutoShutdown PLUS
(FORCEON = GND,
FORCEOFF
= V
CC
)
Receiver Input Threshold to
INVALID
Output High
Receiver Input Threshold to
INVALID
Output Low
INVALID
Output Voltage Low
INVALID,
Output Voltage High
Receiver Positive or Negative
Threshold to
INVALID
High
Receiver Positive or Negative
Threshold to
INVALID
Low
Receiver or Transmitter Edge to
Transmitters Enabled
t
INVH
t
INVL
t
WU
Figure 3a
Figure 3a
I
OUT
= -1.6mA
I
OUT
= -1.0mA
Figure 3b
Figure 3b
Figure 3b (Note 3)
V
V
V
V
µs
µs
µs
s
Receiver or Transmitter Edge to
t
AUTOSHDN
Figure 3b (Note 3)
Transmitters Shut Down
Note 3:
A transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic thresholds.
_______________________________________________________________________________________
3
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
MAX3233E/MAX3235E
TIMING CHARACTERISTICS
(V
CC
= +3.0V to +3.6V for MAX3233E, V
CC
= +4.5V to +5.5V for MAX3235E; T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical val-
ues are at T
A
= +25°C.)
PARAMETER
Maximum Data Rate
t
PHL
Receiver Propagation Delay
t
PLH
Receiver Output Enable Time
Receiver Output Disable Time
Transmitter Skew
Receiver Skew
⏐
t
PHL
- t
PLH
⏐
⏐
t
PHL
- t
PLH
⏐
SYMBOL
CONDITIONS
R
L
= 3kΩ, C
L
= 1000pF,
one transmitter switching
MAX3233E
R_IN to R_OUT,
C
L
= 150pF
Normal operation
Normal operation
(Note 4)
MAX3233E
MAX3235E
MAX3235E
MAX3233E
MAX3235E
MIN
250
70
100
250
150
200
200
150
180
50
ns
ns
ns
ns
ns
ns
TYP
MAX
UNITS
kbps
V
CC
= 3.3V (MAX3233E),
C
L
= 150pF
6
30
V
CC
= 5.0V (MAX3235E),
to 1000pF
T
A
= +25°C,
Transition-Region Slew Rate
Note 2:
A transmitter/receiver edge is defined asR
L
transition
7kΩ,
a = 3kΩ
to
through the transmitter/receiver input logic thresholds.
measured from +3V to -3V
C
L
= 150pF
Note 3:
Transmitter skew is measured at the transmitter zero cross points.
4
30
to 2500pF
or -3V to +3V
Note 4:
Transmitter skew is measured at the transmitter zero crosspoints.
V/µs
__________________________________________Typical Operating Characteristics
(V
CC
= +3.3V for MAX3233E, V
CC
= +5.0V for MAX3235E; 250kbps data rate; all transmitters loaded with 3kΩ and C
L
; T
A
= +25°C,
unless otherwise noted.)
TRANSMITTER OUTPUT VOLTAGE vs.
LOAD CAPACITANCE
MAX3233E/35Etoc01
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3233E/35E toc02
SLEW RATE vs.
LOAD CAPACITANCE
14
12
SLEW RATE (V/µs)
SLEW RATE -
10
8
6
4
SLEW RATE +
MAX3233E/35Etoc01
10.0
TRANSMITTER OUTPUT VOLTAGE (V)
7.5
5.0
2.5
0
-2.5
-5.0
-7.5
0
1000
2000
3000
4000
V
OUT
-
V
OUT
+
45
40
SUPPLY CURRENT (mA)
35
30
25
20
15
10
5
0
TRANSMITTER 1 AT DATA RATE
TRANSMITTER 2 AT 1/16 DATA RATE
16
250kbps
120kbps
20kbps
2
0
0
1000
2000
3000
4000
5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
-10.0
5000
LOAD CAPACITANCE (pF)
4
_______________________________________________________________________________________
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
______________________________________________________________Pin Description
PIN
1
6
2
3
4
5
7
19
8
20
9
10
11, 12
13
14
15
16
17
18
NAME
R2OUT
R1OUT
INVALID
T2IN
T1IN
FORCEON
T1OUT
T2OUT
R1IN
R2IN
V
CC
FORCEOFF
V+
C1+
C1-
C2+
C2-
V-
GND
TTL/CMOS Receiver Outputs
Invalid Signal Detector Output, active low. A logic high indicates that a valid RS-232
level is present on a receiver.
TTL/CMOS Transmitter Outputs
Force-On Input, active high. Drive high to override AutoShutdown Plus, keeping
transmitters and receivers active (FORCEOFF must be high) (Table 1).
RS-232 Transmitter Outputs
RS-232 Receiver Outputs
Supply Voltage (MAX3233E = +3.3V, MAX3235E = +5.0V)
Force-Off Input, active low. Drive low to shut down transmitters, receivers, and charge
pump. This overrides AutoShutdown Plus and FORCEON (Table 1).
+5.5V generated by the charge pump. Do not connect.
Positive terminal of the internal voltage-doubling charge-pump capacitor. Leave
unconnected or connect to an external 0.1µF capacitor. See
Charge Pump
Section.
Negative terminal of the internal voltage-doubling charge-pump capacitor. Leave
unconnected or connect to an external 0.1µF capacitor. See
Charge Pump
Section.
Positive terminal of the internal inverting charge-pump capacitor. Do not connect.
Negative terminal of the internal inverting charge-pump capacitor. Do not connect.
-5.5V generated by the charge pump. Do not connect.
Ground
FUNCTION
MAX3233E/MAX3235E
_______________________________________________________________________________________
5
