19-2667; Rev 1; 1/03
±15kV ESD-Protected, RS-232 Transceivers for
Multidrop Applications
General Description
The MAX3322E/MAX3323E 3.0V to 5.5V powered
EIA/TIA-232 and V.28/V.24 communications interfaces
are designed for multidrop applications with low power
requirements, high data-rate capabilities, and
enhanced electrostatic discharge (ESD) protection. All
RS-232 inputs and outputs are protected to ±15kV
using the IEC 1000-4-2 Air-Gap Discharge method,
±8kV using the IEC 1000-4-2 Contact Discharge
method, and ±15kV using the Human Body Model.
The MAX3322E/MAX3323E have pin-selectable
5kΩ/high-impedance RS-232 receivers. These devices
are capable of receiving data in high-impedance mode.
In multidrop applications, one receiver has a 5kΩ input
resistance, while the other receivers are high imped-
ance to ensure the RS-232 standard is observed. Logic
control permits selection of the functional mode: high
impedance or RS-232 standard load. The transmitters
are enabled by logic control to allow the multiplexing of
the inputs to a single UART.
A proprietary low-dropout transmitter output stage
enables true RS-232 performance from a 3.0V to 5.5V
supply with a dual charge pump. The charge pump
requires only four small 0.1µF capacitors for operation
from a 3.3V supply. The MAX3322E/MAX3323E are
capable of running at data rates up to 250kbps while
maintaining RS-232-compliant output levels. The
MAX3322E/MAX3323E have a unique V
L
pin that allows
operation in mixed-logic voltage systems. Both input
and output logic levels are pin programmable through
the V
L
pin.
The MAX3322E is a 2Tx/2Rx device for hardware hand-
shaking in standard RS-232 mode, and the MAX3323E
is a 1Tx/1Rx, required in most multidrop applications.
The MAX3322E is offered in a space-saving TSSOP
package. The MAX3323E is offered in 16-pin DIP and
space-saving TSSOP packages.
Features
o
Pin-Selectable 5kΩ/High-Impedance Receivers
o
Transmitter Outputs Three-Stated by Logic
Control
o
V
L
Pin for Compatibility with Mixed Voltage
Systems
o
1Tx/1Rx (MAX3323E) or 2Tx/2Rx (MAX3322E)
Versions
o
250kbps Data Rate
o
1µA Low-Power Shutdown
o
High 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
MAX3322E/MAX3323E
Ordering Information
PART
MAX3322E
EUP
MAX3323E
EUE
MAX3323EEPE
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 TSSOP
16 TSSOP
16 DIP
Pin Configurations
TOP VIEW
C1+ 1
V+ 2
C1- 3
C2+ 4
C2- 5
V- 6
TOUT2 7
RIN2 8
TOUT1 9
RIN1 10
20 V
CC
19 GND
18 SHDN
17 V
L
Applications
Bar-Code Scanners
Video Security
Industrial Data Acquisition
Data Splitters
MAX3322E
16 RENABLE
15 TXENABLE
14 TIN2
13 ROUT2
12 TIN1
11 ROUT1
TSSOP
Typical Operating Circuit and Functional Diagram appear
at end of data sheet.
Pin Configurations continued 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, RS-232 Transceivers for
Multidrop Applications
MAX3322E/MAX3323E
ABSOLUTE MAXIMUM RATINGS
All Voltages Referenced to GND
V
CC
, V
L
....................................................................-0.3V to +6V
V+ (Note 1) ....................................................(V
CC
- 0.3V) to +7V
V- (Note 1) ................................................................+0.3V to -7V
V+ + |V-| (Note 1) .................................................................+13V
Input Voltages
TIN_, RENABLE, TXENABLE,
SHDN
.....................-0.3V to +6V
RIN_ ..................................................................................±25V
Output Voltages
TOUT_............................................................................±13.2V
ROUT_........................................................-0.3V to (V
L
+ 0.3V)
Short-Circuit Duration TOUT_ to GND........................Continuous
Continuous Power Dissipation (T
A
= +70°C)
16-Pin DIP (derate 10.5mW/°C above +70°C) ............842mW
16-Pin TSSOP (derate 9.4mW/°C above +70°C) ........755mW
20-Pin TSSOP(derate 11mW/°C above +70°C) ..........879mW
Operating Temperature Range
MAX3322E/MAX3323E ...................................-40°C to +85°C
Junction Temperature ..................................................... +150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V.
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.
DC ELECTRICAL CHARACTERISTICS
(V
CC
= 3.0V to 5.5V, V
L
= 1.65V to 5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%; C1 = 0.047µF, C2 = C3 = C4 = 0.33µF, tested at +5V
±10%; T
A
= T
MIN
to T
MAX
. Typical values are at V
CC
= V
L
= 3.3V and T
A
= +25°C, unless otherwise noted.)
PARAMETER
DC CHARACTERISTICS
Supply Current Normal Operation
Supply Current in Shutdown
TRANSMITTER LOGIC INPUTS
Input Logic Threshold Low
Input Logic Threshold High
Transmitter Input Hysteresis
Input Leakage Current
Input Logic Threshold Low
Input Logic Threshold High
Input Leakage Current
RECEIVER OUTPUTS
Output Leakage Current
Output Voltage Low
Output Voltage High
RECEIVER INPUTS
Input Voltage Range
Input Threshold Low
V
RIN
V
L
= 1.65V
V
L
= 3.3V
V
L
= 5.0V
-25
0.25
0.6
0.8
0.6
1.2
1.5
V
+25
V
I
OL
V
OL
V
OH
Receivers disabled,
SHDN
= 0V
I
OUT
= 1.6mA, V
L
> 1.8V
I
OUT
= 1mA, V
L
≤
1.8V
I
OUT
= -1mA, V
L
> 1.8V
I
OUT
= -500µA, V
L
≤
1.8V
V
L
- 0.4 V
L
- 0.1
V
L
- 0.4 V
L
- 0.1
+0.05
+10
0.4
0.4
µA
V
V
2/3 x V
L
±0.01
±1
I
IL
LOGIC INPUTS (TXENABLE, RENABLE,
SHDN)
0.4
V
V
µA
V
L
≤
1.8V
V
L
> 1.8V
V
L
- 0.4
2/3 x V
L
0.2
±0.01
±1
0.4
V
V
V
µA
I
CC
I
CC(SHDN)
SHDN
= V
L
, no load
SHDN
= 0V, no load
1
1
10
mA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
±15kV ESD-Protected, RS-232 Transceivers for
Multidrop Applications
DC ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 3.0V to 5.5V, V
L
= 1.65V to 5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%; C1 = 0.047µF, C2 = C3 = C4 = 0.33µF, tested at +5V
±10%; T
A
= T
MIN
to T
MAX
. Typical values are at V
CC
= V
L
= 3.3V and T
A
= +25°C, unless otherwise noted.)
PARAMETER
Input Threshold High
Input Hysteresis
RENABLE = 1
Input Resistance
TRANSMITTER OUTPUTS
Output Voltage Swing
Output Resistance
Output Short-Circuit Current
Output Leakage Current
ESD PROTECTION
Human Body Model
RIN, TOUT
IEC 1000-4-2 Air-Gap Discharge
IEC 1000-4-2 Contact Discharge
±15
±15
±8
kV
All transmitter outputs loaded with 3kΩ to
ground
V
CC
= V+ = V- = 0, TOUT_ = ±2V,
TXENABLE = 1
V
OUT
= 0V
V
OUT
= ±12V, transmitters disabled
±5
300
±5.4
10M
±60
±25
V
Ω
mA
µA
R
IN
RENABLE = 0 or
SHDN
= 0V, R
IN
from -13V
to +13V
3
1
SYMBOL
V
L
= 1.65V
V
L
= 3.3V
V
L
= 5.0V
CONDITIONS
MIN
TYP
1
1.5
1.8
0.35
5
7
MAX
1.4
2.4
2.4
V
kΩ
MΩ
V
UNITS
MAX3322E/MAX3323E
TIMING CHARACTERISTICS
(V
CC
= 3.0V to 5.5V, V
L
= 1.65V to 5.5V, C1–C4 = 0.1µF, tested at +3.3V ±10%; C1 = 0.047µF, C2 = C3 = C4 = 0.33µF, tested at +5V
±10%; T
A
= T
MIN
to T
MAX
. Typical values are at V
CC
= V
L
= 3.3V and T
A
= +25°C, unless otherwise noted.)
PARAMETER
Maximum Data Rate
Receiver Propagation Delay
Transmitter Propagation Delay
Time to Enter Three-State on Tx
Time to Exit Three-State on Tx
Time to Enable Resistor
Time to Disable Resistor
Time to Enter Shutdown
Time to Exit Shutdown
Transmitter Skew
Receiver Skew
Transition Region Slew Rate
R
L
= 3kΩ to 7kΩ, C
L
= 1000pF, measured
from +3V to -3V or vice versa
6
t
PHL
t
PLH
t
PHL
t
PLH
SYMBOL
CONDITIONS
R
L
= 3kΩ, C
L
= 1000pF, one transmitter
switching
RIN_ to ROUT_, C
L
= 30pF, V
L
= 3.3V,
Figure 2
TIN_ to TOUT_, R
L
= 3kΩ, C
L
= 1000pF,
Figure 1
(Note 2)
(Note 2)
(Note 2)
(Note 2)
MIN
250
150
180
0.6
0.7
10
3
0.4
0.2
50
50
100
30
30
50
50
10
10
TYP
MAX
UNITS
kbps
ns
µs
µs
µs
µs
µs
µs
µs
ns
ns
V/µs
Note 2:
Guaranteed by design. Not production tested.
_______________________________________________________________________________________
3
±15kV ESD-Protected, RS-232 Transceivers for
Multidrop Applications
MAX3322E/MAX3323E
Typical Operating Characteristics
(V
CC
= 3.3V, V
L
= 3.3V, C1–C4 = 0.1µF, T
A
= +25°C.)
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3322E toc01
SLEW RATE
vs. LOAD CAPACITANCE
MAX3322E toc02
7.5
5.0
OUTPUT VOLTAGE (V)
2.5
0
-2.5
-5.0
DATA RATE = 250kbps
LOAD = 3kΩ IN PARALLEL WITH C
L
18
15
SLEW RATE-
SLEW RATE (V/µs)
12
9
6
3
0
SLEW RATE+
-7.5
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE
vs. DATA RATE
MAX3322E toc03
SUPPLY CURRENT
vs. LOAD CAPACITANCE
LOAD = 3kΩ
ONE TRANSMITTER
SWITCHING AT DATA
RATE, OTHER
TRANSMITTER
AT 1/8 DATA RATE
MAX3322E toc04
7.5
5.0
OUTPUT VOLTAGE (V)
2.5
0
-2.5
-5.0
-7.5
0
50
100
150
200
40
250kbps
SUPPLY CURRENT (mA)
LOAD = 3kΩ, 1000pF
ONE TRANSMITTER
SWITCHING AT DATA
RATE, OTHER
TRANSMITTER
AT 1/8 DATA RATE
30
20
125kbps
10
40kbps
0
250
0
1000
2000
3000
4000
5000
DATA RATE (kbps)
LOAD CAPACITANCE (pF)
RECEIVER INPUT RESISTANCE
vs. INPUT VOLTAGE RANGE
MAX3322E toc05
RECEIVER INPUT RESISTANCE
vs. INPUT VOLTAGE RANGE
RENABLE = 0
V
L
= 5V
4
MAX3322E toc06
5.50
RENABLE = 1
RECEIVER INPUT RESISTANCE (kΩ)
5.25
5
RECEIVER INPUT RESISTANCE (MΩ)
3
5.00
2
4.75
1
4.50
-25
-15
-5
V
RIN
(V)
5
15
25
0
-25
-15
-5
V
RIN
(V)
5
15
25
4
_______________________________________________________________________________________
±15kV ESD-Protected, RS-232 Transceivers for
Multidrop Applications
Pin Description
PIN
MAX3322E
1
2
3
4
5
6
7, 9
8, 10
11, 13
12, 14
15
MAX3323E
1
2
3
4
5
6
7
8
9
10
11
NAME
C1+
V+
C1-
C2+
C2-
V-
TOUT_
RIN_
ROUT_
TIN_
TXENABLE
FUNCTION
Positive Terminal of the Voltage-Doubler Charge-Pump Capacitor
+5.5V Generated by the Charge Pump
Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor
Positive Terminal of the Inverting Charge-Pump Capacitor
Negative Terminal of the Inverting Charge-Pump Capacitor
-5.5V Generated by the Charge Pump
Transmitter Output
Receiver Input
Receiver Output
Transmitter Input
Transmitter Enable. Drive TXENABLE high to enable transmitter. Drive TXENABLE low
to put transmitter into high impedance.
Receiver Termination Enable. Drive RENABLE high for normal RS-232 5kΩ termination.
Drive RENABLE low to make receiver inputs high impedance. In either case, the
receiver and its output are enabled.
Logic-Level Supply. All CMOS inputs and outputs are referred to V
L
, which is from
1.65V to 5.5V.
Shutdown Input. Drive
SHDN
low to put device into shutdown mode. Drive
SHDN
high
for normal operation. In shutdown, all transmitter and receiver outputs are in three-state;
receiver inputs are high impedance.
Ground
+3V to +5.5V Input Voltage. Bypass V
CC
to GND with a 0.1µF capacitor.
MAX3322E/MAX3323E
16
12
RENABLE
17
13
V
L
18
19
20
14
15
16
SHDN
GND
V
CC
Detailed Description
The MAX3322E/MAX3323E are RS-232 transceivers for
multidrop applications (i.e., multiple-receiver operation).
The devices are pin selectable between standard RS-232
operation with 5kΩ input resistance receivers or high-
input-impedance receivers. Receivers of the MAX3322E/
MAX3323E remain active in both modes of operation. In
multidrop applications, a selected receiver is set at a 5kΩ
input resistance, while the others are high-input imped-
ance, maintaining RS-232 standards. Logic control per-
mits selection of the functional mode: high impedance or
normal load. The transmitters are enabled by logic control
to allow transmission-line sharing.
The logic supply input (V
L
) controls the levels of the
system’s I/O and works from 1.65V to 5.5V, providing
compatibility with lower microprocessor I/O voltages.
The transmitters are inverting level translators that con-
vert CMOS logic levels into RS-232-compatible levels.
They guarantee 250kbps with loads of R
L
= 3kΩ and C
L
= 1000pF. The transmitters are enabled or disabled
(three-stated) by the logic control TXENABLE, which
manages transmission-line sharing in multidrop applica-
tions. When TXENABLE is high, the transmitter is
enabled. When TXENABLE is low, the transmitter is put
in high-impedance state. The receivers can be used in
two conditions, selectable by the logic control RENABLE.
When RENABLE is high, the internal 5kΩ resistor is con-
nected across receiver input and ground. When
RENABLE is low, the receiver input is high impedance,
while maintaining receiving capability.
In shutdown mode, all transmitter and receiver outputs
are three-stated, receiver inputs are in high impedance,
the charge pump is turned off, V+ decays to V
CC
, and
V- decays to ground. ESD protection structures are
incorporated in all pins to protect against ESD events
encountered during handling and assembly. The
receiver inputs and the transmitter outputs have ±15kV
ESD structure implementation.
5
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