MAX3233E_V01 [MAXIM]
±15kV ESD-Protected, 1μA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors;
| 型号： | MAX3233E_V01 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | ±15kV ESD-Protected, 1μA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors |
| 文件： | 总12页 (文件大小：263K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1473; Rev 2; 8/04
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
________________General Description
____________________________Features
The MAX3233E/MAX3235E are EIA/TIA-232 and V.28/V.24
communications interfaces with automatic shutdown/
wa ke -up fe a ture s , hig h d a ta -ra te c a p a b ilitie s , a nd
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.
♦ 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
All devices achieve a 1µA supply current using Maxim’s
re volutiona ry AutoShutd own Plus ™ fe a ture . The s e
d e vic e s a utoma tic a lly e nte r a low-p owe r s hutd own
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.
+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
Pin Configuration/
Functional Diagram
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.
1
20
R2OUT
R2IN
MAX3233E
MAX3235E
2
3
4
5
19
18
17
T2OUT
INVALID
________________________Applications
GND
V-
T2IN
T1IN
Subnotebook and Palmtop Computers
Cellular Phones
Battery-Powered Equipment
Handheld Equipment
Peripherals
16
C2-
FORCEON
R1OUT
6
7
8
9
15
14
13
C2+
CHARGE
PUMP
Embedded Systems
T1OUT
R1IN
C1-
_______________Ordering Information
C1+
PART
TEMP RANGE
PIN-PACKAGE
12
11
V
CC
V+
V+
MAX3233ECWP
MAX3233ECPP
MAX3233EEWP
MAX3233EEPP
0°C to +70°C
0°C to +70°C
20 SO
10
20 Plastic DIP
20 SO
FORCEOFF
-40°C to +85°C
-40°C to +85°C
20 Plastic DIP
SO/DIP
Ordering Information continued at end of data sheet.
AutoShutdown Plus is a trademark of Maxim Integrated Products, Inc.
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
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND (MAX3233E).........................................-0.3V to +4V
Short-Circuit Duration
V
CC
to GND (MAX3235E).........................................-0.3V to +6V
T_OUT to GND ......................................................Continuous
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
Continuous Power Dissipation (T = +70°C)
A
Wide SO (derate 10mW/°C above +70°C)..................800mW
Plastic DIP (derate 11.11mW/°C above +70°C) .........889mW
Operating Temperature Ranges
T_IN, FORCEON, FORCEOFF to GND....................-0.3V to +6V
R_IN to GND ...................................................................±25V
Output Voltages
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
T_OUT to GND.............................................................±13.2V
R_OUT, INVALID to GND ......................-0.3V to (V + 0.3V)
CC
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 = +3.0V to +3.6V for MAX3233E, V = +4.5V to +5.5V for MAX3235E; T = T
to T , unless otherwise noted. Typical val-
MAX
CC
CC
A
MIN
ues are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS (V = 3.3V for MAX3233E, V = 5.0V for MAX3235E, T = +25°C )
CC
.
CC
A
Supply Current,
AutoShutdown Plus
FORCEON = GND, FORCEOFF = V
all R_IN idle, all T_IN idle
,
CC
1
1
10
10
1
µA
µA
Supply Current, Shutdown
Supply Current,
FORCEOFF = GND
0.3
mA
FORCEON = FORCEOFF = V , no load
CC
AutoShutdown Plus Disabled
LOGIC INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
0.8
V
V
T_IN, FORCEON, FORCEOFF
V
= 3.3V, MAX3233E
= 5.0V, MAX3235E
2
T_IN, FORCEON,
CC
Input Logic Threshold High
FORCEOFF
V
CC
2.4
Transmitter Input Hysteresis
Input Leakage Current
Output Voltage Low
0.5
V
µA
V
±0.01
±1
T_IN, FORCEON, FORCEOFF
I
= 1.6mA
= -1.0mA
0.4
OUT
Output Voltage High
RECEIVER INPUTS
Input Voltage Range
I
V
- 0.6 V - 0.1
V
OUT
CC
CC
-25
0.6
0.8
+25
V
V
V
= 3.3V, MAX3233E
= 5.0V, MAX3235E
= 3.3V, MAX3233E
= 5.0V, MAX3235E
1.0
1.3
1.5
1.8
0.5
5
CC
Input Threshold Low
Input Threshold High
T
= +25°C
= +25°C
A
V
CC
V
CC
2.4
2.4
T
A
V
V
CC
Input Hysteresis
Input Resistance
V
T
A
= +25°C
3
7
kΩ
2
_______________________________________________________________________________________
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
ELECTRICAL CHARACTERISTICS (continued)
(V = +3.0V to +3.6V for MAX3233E, V = +4.5V to +5.5V for MAX3235E; T = T
to T , unless otherwise noted. Typical val-
MAX
CC
CC
A
MIN
ues are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
TRANSMITTER OUTPUTS
All transmitter outputs loaded with 3kΩ to
Output Voltage Swing
±5
±5.4
10M
V
ground
Output Resistance
V
= V+ = V- = 0, transmitter outputs = ±2V
300
Ω
CC
Output Short-Circuit Current
±60
±25
mA
V
= 0 or +3.0V to
CC
V
= ± 12V
OUT
3.6V (MAX3233E)
Output Leakage Current
transmitters
disabled
µA
kV
V
= 0 or +4.5V to
CC
±25
5.5V (MAX3235E)
ESD PROTECTION
IEC1000-4-2 Air Discharge
IEC1000-4-2 Contact Discharge
Human Body Model
±15
±8
R_IN, T_OUT
±15
AutoShutdown PLUS (FORCEON = GND, FORCEOFF = V
)
CC
Positive threshold
Negative threshold
2.7
Receiver Input Threshold to
INVALID Output High
Figure 3a
Figure 3a
V
V
-2.7
-0.3
Receiver Input Threshold to
INVALID Output Low
0.3
0.4
I
= -1.6mA
V
V
INVALID Output Voltage Low
INVALID, Output Voltage High
OUT
I
= -1.0mA
V
- 0.6
OUT
CC
Receiver Positive or Negative
Threshold to INVALID High
t
Figure 3b
Figure 3b
1
µs
µs
µs
s
INVH
MAX3233E
MAX3235E
70
50
Receiver Positive or Negative
Threshold to INVALID Low
t
INVL
Receiver or Transmitter Edge to
Transmitters Enabled
t
Figure 3b (Note 3)
100
30
WU
Receiver or Transmitter Edge to
Transmitters Shut Down
tAUTOSHDN Figure 3b (Note 3)
15
60
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
TIMING CHARACTERISTICS
(V = +3.0V to +3.6V for MAX3233E, V = +4.5V to +5.5V for MAX3235E; T = T
to T , unless otherwise noted. Typical val-
MAX
CC
CC
A
MIN
ues are at T = +25°C.)
A
PARAMETER
SYMBOL
CONDITIONS
= 3kΩ, C = 1000pF,
MIN
TYP
MAX
UNITS
R
L
L
Maximum Data Rate
250
kbps
one transmitter switching
MAX3233E
MAX3235E
MAX3233E
MAX3235E
70
t
t
PHL
100
250
150
200
200
150
180
50
R_IN to R_OUT,
= 150pF
Receiver Propagation Delay
ns
C
L
PLH
Receiver Output Enable Time
Receiver Output Disable Time
Transmitter Skew
Normal operation
Normal operation
(Note 4)
ns
ns
ns
t
- t
⏐ PHL PLH ⏐
MAX3233E
MAX3235E
Receiver Skew
t
- t
ns
⏐ PHL PLH ⏐
V
= 3.3V (MAX3233E),
= 5.0V (MAX3235E),
= +25°C,
CC
C
= 150pF
L
6
30
30
V
CC
to 1000pF
T
A
Transition-Region Slew Rate
V/µs
R = 3kΩ to 7kΩ,
L
C
= 150pF
L
measured from +3V to -3V
4
to 2500pF
or -3V to +3V
Note 4: Transmitter skew is measured at the transmitter zero crosspoints.
__________________________________________Typical Operating Characteristics
(V = +3.3V for MAX3233E, V = +5.0V for MAX3235E; 250kbps data rate; all transmitters loaded with 3kΩ and C ; T = +25°C,
CC
CC
A
L
unless otherwise noted.)
OPERATING SUPPLY CURRENT
vs. LOAD CAPACITANCE
TRANSMITTER OUTPUT VOLTAGE vs.
LOAD CAPACITANCE
SLEW RATE vs.
LOAD CAPACITANCE
45
40
35
30
25
20
15
10
5
10.0
7.5
16
14
12
10
8
TRANSMITTER 1 AT DATA RATE
TRANSMITTER 2 AT 1/16 DATA RATE
V
+
OUT
5.0
SLEW RATE -
250kbps
2.5
0
120kbps
SLEW RATE +
-2.5
-5.0
-7.5
-10.0
6
V
OUT
-
4
20kbps
2
0
0
0
1000
2000
3000
4000
5000
0
1000
2000
3000
4000
5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
4
_______________________________________________________________________________________
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
______________________________________________________________Pin Description
PIN
1
NAME
R2OUT
R1OUT
FUNCTION
TTL/CMOS Receiver Outputs
6
Invalid Signal Detector Output, active low. A logic high indicates that a valid RS-232
level is present on a receiver.
2
INVALID
3
4
T2IN
T1IN
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).
5
FORCEON
7
19
8
T1OUT
T2OUT
R1IN
RS-232 Transmitter Outputs
RS-232 Receiver Outputs
20
9
R2IN
V
CC
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).
10
11, 12
13
FORCEOFF
V+
+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.
C1+
Negative terminal of the internal voltage-doubling charge-pump capacitor. Leave
unconnected or connect to an external 0.1µF capacitor. See Charge Pump Section.
14
C1-
15
16
17
18
C2+
C2-
V-
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
GND
_______________________________________________________________________________________
5
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
_______________Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3233E/MAX3235E’s inte rna l p owe r s up p ly
consists of a regulated dual charge pump that provides
output voltages of +5.5V (doubling charge pump) and
-5.5V (inverting charge pump), with no external capaci-
tors . The c ha rg e p ump op e ra te s in d is c ontinuous
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.
POWER-
MANAGEMENT
UNIT OR
KEYBOARD
CONTROLLER
FORCEOFF
FORCEON
INVALID
MAX3233E
MAX3235E
RS-232 Transmitters
The tra ns mitte rs a re inve rting le ve l tra ns la tors tha t
convert CMOS-logic levels to 5.0V EIA/TIA-232 levels.
The devices guarantee a 250kbps data rate with worst-
case loads of 3kΩ in parallel with 1000pF, providing
compatibility with PC-to-PC communication software
(such as LapLink™). Transmitters can be paralleled to
drive multiple receivers. Figure 1 shows a complete
system connection.
I/O
CHIP
WITH
UART
RS-232
CPU
When FORCEOFF is driven to ground or when the Auto-
Shutdown Plus circuitry senses that all receiver and
transmitter inputs are inactive for more than 30sec, the
transmitters are disabled and the outputs go into a high-
impedance state. When powered off or shut down, the
outputs can be driven to ±12V. The transmitter inputs
do not have pull-up resistors. Connect unused inputs to
Figure 1. Interface Under Control of PMU
+0.3V
GND or V
.
CC
R_IN
80µs
TIMER
R
RS-232 Receivers
INVALID
The receivers convert RS-232 signals to CMOS-logic
output levels. They feature inverting outputs that always
remain active (Table 1).
-0.3V
INVALID ASSERTED IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR
The MAX3233E/MAX3235E feature an INVALID output
that is enabled low when no valid RS-232 voltage levels
have been detected on all receiver inputs. Because
INVALID indicates the receiver input’s condition, it is
ind e p e nd e nt of FORCEON a nd FORCEOFF s ta te s
(Figures 2 and 3).
AT LEAST 80µs.
Figure 2a. INVALID Functional Diagram, INVALID Low
+2.7V
AutoShutdown Plus Mode
The devices achieve a 1µA supply current with Maxim’s
AutoShutd own Plus fe a ture , whic h op e ra te s whe n
FORCEOFF is high and a FORCEON is low. When these
devices do not sense a valid signal transition on any
receiver or transmitter input for 30sec, the on-board
charge pumps are shut down, reducing supply current
to 1µA. This occurs if the RS-232 cable is disconnected,
or if the connected peripheral transmitters are turned off
and the UART driving the transmitter inputs is inactive.
The system turns on again when a valid transition is
R_IN
80µs
TIMER
R
INVALID
-2.7V
INVALID DEASSERTED IF ANY RECEIVER INPUT HAS BEEN ABOVE +2.7V OR BELOW
-2.7V FOR 1µs.
Figure 2b. INVALID Functional Diagram, INVALID High
LapLink is a trademark of Traveling Software.
6
_______________________________________________________________________________________
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
Table 1. Output Control Truth Table
VALID
RECEIVER
LEVEL
Rx or Tx EDGE
WITHIN 30sec
OPERATION STATUS
FORCEON
T_OUT
R_OUT
FORCEOFF
Shutdown (Forced Off)
X
0
X
X
X
X
High-Z
Active
Active
High-Z
Active
Active
High-Z
Active
High-Z
Active
Active
Active
Active
Active
Active
Active
Active
Active
Normal Operation (Forced On)
1
1
Normal Operation
(AutoShutdown Plus)
0
1
X
Yes
No
X
Shutdown
(AutoShutdown Plus)
0
1
X
Normal Operation
Normal Operation
Shutdown
1
Yes
X
INVALID*
INVALID*
INVALID*
INVALID*
INVALID*
1
Yes
No
X
1
No
Yes
No
Normal Operation
(AutoShutdown)
INVALID**
INVALID**
Shutdown (AutoShutdown)
X
X = Don’t care
* INVALID connected to FORCEON
** INVALID connected to FORCEON and FORCEOFF
EDGE
T_IN
FORCEOFF
DETECT
FORCEOFF
POWERDOWN*
S
AUTOSHDN*
30sec
TIMER
FORCEON
AUTOSHDN
EDGE
DETECT
R_IN
R
*
POWERDOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL
STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES.
FORCEON
*AUTOSHDN IS ONLY AN INTERNAL SIGNAL.
Figure 2d. Power-Down Logic
Figure 2c. AutoShutdown Plus Logic
applied to any RS-232 receiver or transmitter input. As a
result, the system saves power without changes to the
existing BIOS or operating system.
OFF override AutoShutdown Plus circuitry. When nei-
ther control is asserted, the IC selects between these
states automatically based on the last receiver or trans-
mitter input edge received.
Figures 2a and 2b depict invalid and valid RS-232
receiver voltage levels. INVALID indicates the receiver
input’s condition, and is independent of FORCEON and
FORCEOFF states. Figure 2 and Tables 1 and 2 sum-
marize the operating modes. FORCEON and FORCE-
When shut down, the device’s charge pumps turn off,
V+ is pulled to V , V- is pulled to ground, and the
CC
tra ns mitte r outp uts a re hig h imp e d a nc e . The time
required to exit shutdown is typically 100µs (Figure 7).
_______________________________________________________________________________________
7
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
MAX3235E is awake. If another system outputs valid
RS-232 signal transitions within that time, the RS-232
ports on both systems remain enabled.
By connecting FORCEON to INVALID, the device shuts
down when no valid receiver level and no receiver or
transmitter edge is detected for 30sec. It wakes up
when a valid receiver level or receiver or transmitter
edge is detected.
Software-Controlled Shutdown
If direct software control is desired, use INVALID to
indicate DTR or Ring Indicator signal. Tie FORCEOFF
and FORCEON together to bypass the AutoShutdown
Plus so the line acts like a SHDN input.
By connecting FORCEON and FORCEOFF to INVALID,
the device shuts down when no valid receiver level is
detected and wakes up when a valid receiver level is
detected.
±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 have extra pro-
tection 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 powered down. After an ESD
A system with AutoShutdown Plus may need time to
wa ke up . Fig ure 4 s hows a c irc uit tha t forc e s the
tra ns mitte rs on for 100ms , a llowing e noug h time
for a nothe r s ys te m to re a lize tha t the MAX3233E/
INVALID HIGH
+2.7
INDETERMINATE
+0.3
Table 2. INVALID Truth Table
0
INVALID LOW
INDETERMINATE
INVALID HIGH
-0.3
RS-232 SIGNAL
PRESENT AT ANY
RECEIVER INPUT
INVALID OUTPUT
-2.7
Yes
No
High
Low
Figure 3a. Receiver Positive/Negative Thresholds for INVALID
RECEIVER
INPUTS
INVALID
REGION
}
TRANSMITTER
INPUTS
TRANSMITTER
OUTPUTS
V
INVALID
OUTPUT
CC
t
INVL
t
INVH
t
0
AUTOSHDN
t
AUTOSHDN
t
t
WU
WU
V+
V
CC
0
V-
Figure 3b. AutoShutdown Plus, INVALID, and READY Timing Diagram
_______________________________________________________________________________________
8
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
R 50MΩ to 100MΩ
R 330Ω
C
D
POWER-
MANAGEMENT
UNIT
MASTER SHDN LINE
0.1µF
1MΩ
DISCHARGE
RESISTANCE
CHARGE CURRENT
LIMIT RESISTOR
FORCEOFF FORCEON
HIGH-
VOLTAGE
DC
DEVICE
UNDER
TEST
C
s
150pF
STORAGE
CAPACITOR
SOURCE
MAX3233E
MAX3235E
Figure 6a. IEC 1000-4-2 ESD Test Model
Figure 4. AutoShutdown Plus Initial Turn-On to Wake Up
Another System
ESD p rote c tion c a n b e te s te d in va rious wa ys ; the
transmitter outputs and receiver inputs of this product
family are characterized for protection to the following
limits:
R 1MΩ
C
R 1500Ω
D
1) ±15kV using the Human Body Model
DISCHARGE
RESISTANCE
CHARGE-CURRENT
LIMIT RESISTOR
2) ±8kV using the Contact Discharge method specified
in IEC 1000-4-2
HIGH-
VOLTAGE
DC
DEVICE
UNDER
TEST
C
s
100pF
STORAGE
CAPACITOR
3) ± 15kV us ing IEC 1000-4-2’s Air-Ga p Dis c ha rg e
method
SOURCE
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 and Figure 5b
shows the current waveform it generates when dis -
charged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of inter-
e s t, whic h is the n d is c ha rg e d into the te s t d e vic e
through a 1.5kΩ resistor.
Figure 5a. Human Body ESD Test Model
I 100%
P
90%
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
I
r
AMPERES
36.8%
IEC 1000-4-2
The IEC 1000-4-2 standard covers ESD testing and per-
formance of finished equipment; it does not specifically
refer to integrated circuits. The MAX3233E/MAX3235E
help you design equipment that meets Level 4 (the high-
est level) of IEC 1000-4-2, without the need for additional
ESD-protection components.
10%
0
TIME
0
t
RL
t
DL
CURRENT WAVEFORM
The major difference between tests done using the
Human Body Model and IEC 1000-4-2 is higher peak cur-
rent in IEC 1000-4-2, because series resistance is lower
in the IEC 1000-4-2 model. Hence, the ESD withstand
voltage measured to IEC 1000-4-2 is generally lower than
Figure 5b. Human Body Current Waveform
e ve nt, Ma xim’s E ve rs ions ke e p working without
la tc hup , whe re a s c omp e ting RS-232 p rod uc ts c a n
latch and must be powered down to remove latchup.
_______________________________________________________________________________________
9
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
V
CC
I
C
BYPASS
100%
90%
V
CC
MAX3233E
MAX3235E
T_ OUT
T_ IN
10%
R_ IN
R_ OUT
t
t = 0.7ns to 1ns
r
30ns
5kΩ
1000pF
FORCEON
FORCEOFF
60ns
V
CC
GND
Figure 6b. IEC 1000-4-2 ESD Generator Current Waveform
Figure 8. Loopback Test Circuit
5V/div
0
manufacturing. Of course, all pins require this protec-
tion during manufacturing, not just RS-232 inputs and
outp uts . The re fore , a fte r PC b oa rd a s s e mb ly, the
Machine Model is less relevant to I/O ports.
T1OUT
FORCEON = FORCEOFF
2V/div
0
__________Applications Information
Charge Pumps
The MAX3233E/MAX3235E d o not re q uire e xte rna l
capacitors to operate their internal charge pumps.
T2OUT
V
CC
= 3.3V
10V/div
0
The MAX3235E can be operated down to 3.0V by par-
alleling the internal C1 capacitor with an external 0.1µF.
When using an external capacitor across the C1 termi-
nals, check to confirm that the total supply voltage
measured from V+ to V- does not exceed the absolute
ma ximum volta g e of 13V. With the e xte rna l 0.1µF
capacitor added, the MAX3235E should not be used
with a supply greater than +3.9V.
10µs/div
Figure 7. Transmitter Outputs when Exiting Shutdown or
Powering Up
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.
Power-Supply Decoupling
In most applications, a 0.1µF V
bypass capacitor is
CC
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.
adequate. Connect bypass capacitors as close to the
IC as possible.
Transmitter Outputs
when Exiting Shutdown
Figure 7 shows two transmitter outputs when exiting
shutdown mode. As they become active, the two trans-
mitter outputs are shown going to opposite RS-232
levels (one transmitter input is high, the other is low).
Machine Model
The Ma c hine Mod e l for ESD te s ts a ll p ins us ing a
200pF storage capacitor and zero discharge resis -
tance. Its objective is to emulate the stress caused by
contact that occurs with handling and assembly during
10 ______________________________________________________________________________________
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
Each transmitter is loaded with 3kΩ in parallel with
1000pF. The transmitter outputs display no ringing or
undesirable transients as they come out of shutdown.
Note that the transmitters are enabled only when the
magnitude of V- exceeds approximately -3V.
Figure 9, all transmitters were driven simultaneously at
120kbps into RS-232 loads in parallel with 1000pF. For
Figure 10, a single transmitter was driven at 250kbps,
and all transmitters were loaded with an RS-232 receiv-
er in parallel with 250pF.
High Data Rates
The MAX3233E/MAX3235E maintain the RS-232 ±5.0V
minimum transmitter output voltage even at high data
rates. Figure 8 shows a transmitter loopback test cir-
cuit. Figure 9 shows a loopback test result at 120kbps,
and Figure 10 shows the same test at 250kbps. For
Interconnection with 3V and 5V Logic
The MAX3233E/MAX3235E can directly interface with
va rious 5V log ic fa milie s , inc lud ing ACT a nd HCT
CMOS. See Table 3 for more information on possible
combinations of interconnections.
5V/div
5V/div
T1IN
T1IN
5V/div
5V/div
T1OUT
T1OUT
5V/div
5V/div
R1OUT
R1OUT
V
CC
= 3.3V (MAX3233E), V = 5.0V (MAX3235E)
CC
V
CC
= 3.3V (MAX3233E), V = 5.0V (MAX3235E)
CC
2µs/div
2µs/div
Figure 10. Loopback Test Result at 250kbps
Figure 9. Loopback Test Result at 120kbps
Table 3. Logic Family Compatibility with Various Supply Voltages
LOGIC POWER-SUPPLY
V
CC
DEVICE
VOLTAGE
(V)
SUPPLY VOLTAGE
(V)
COMPATIBILITY
MAX3233E
MAX3233E
MAX3235E
3.3
5
3.3
3.3
5
Compatible with all CMOS families
Compatible with ACT and HCT CMOS, and
with AC, HC, or CD4000 CMOS
3.3/5
Compatible with all TTL and CMOS families
______________________________________________________________________________________ 11
±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual
RS-232 Transceivers with Internal Capacitors
Typical Operating Circuit
Ordering Information (continued)
PART
TEMP RANGE
PIN-PACKAGE
V
CC
9
C
0.1µF
BYPASS
MAX3235ECWP
MAX3235ECPP
MAX3235EEWP
MAX3235EEPP
0°C to +70°C
0°C to +70°C
20 SO
V
CC
11, 12
17
13
20 Plastic DIP
20 SO
C1+
V+
V-
-40°C to +85°C
-40°C to +85°C
14
15
16
C1-
MAX3233E
MAX3235E
20 Plastic DIP
C2+
C2-
___________________Chip Information
4
3
6
T1IN
T1OUT
T2OUT
7
TRANSISTOR COUNT: 1129
TTL/CMOS
INPUTS
RS-232
OUTPUTS
19
T2IN
Package Information
8
R1OUT
R1IN
R2IN
For the latest package outline information, go to
www.maxim-ic.com/packages.
TTL/CMOS
OUTPUTS
RS-232
INPUTS
5kΩ
5kΩ
1
R2OUT
20
INVALID
2
AUTOSHUTDOWN
PLUS
FORCEOFF 10
FORCEON
V
CC
5
GND
18
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circu
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
it patent licenses are
12 ____________________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.
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