3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
General Description
Benefits and Features
The MAX13234E-MAX13237E are a family of 2x2 and
1x1 RS-232 and V.28/V.24 transceivers with high speed
data rates up to 3Mbps that operate from either a 3.3V
or 5V supply.
All devices achieve a 1µA supply current using Maxim’s
AutoShutdown Plus™ feature. These devices automatically enter a low-power shutdown mode when the
RS-232 cable is disconnected or the devices driving
the transmitter and receiver inputs are inactive for more
than 30s.
• Data Rate Up to 3Mbps for Faster Throughput
• Saves Board Space
The MAX13234E–MAX13237E are available in spacesaving TQFN and TSSOP packages and operate over
the -40°C to +85°C temperature range.
• Integrated Low-Voltage Logic for Easy Interface
with ASICs and Microcontrollers
• Integrated ±15kV HBM ESD Protection
• Integrated Charge-Pump Circuitry Requiring Only
•
•
•
•
Applications
•
•
•
•
•
•
•
•
Four External 0.1µF Capacitors for 3.3V Operation
+3V to +5.5V Supply Voltage
AutoShutdown Plus Achieves 1µA Shutdown Current
Reduces Power Consumption
Available in 20-pin TSSOP, TQFN-EP, and 16-pin
TQFN
-40°C to +85°C Operating Temperature
Functional Diagrams
Telematics
GPS Systems
Industrial Systems
Portable Devices
Wireless Modules
POS Systems
Communication Systems
Data Cables
1.62V to VCC
3.0V to 5.5V
CBYPASS1
CBYPASS2
VL
VCC
C1+
V+
C1
C3
C1-
MAX13234E
MAX13235E
C2+
V-
C2
C4
C2T1IN
T1OUT
T2IN
T2OUT
RS-232
OUTPUTS
R1OUT
TTL/CMOS
OUTPUTS
R2OUT
LOGIC-LEVEL TRANSLATION
TTL/CMOS
INPUTS
R1IN
5kΩ
RS-232
INPUTS
R2IN
FORCEOFF
5kΩ
FORCEON
READY
GND
Functional Diagrams continued at end of data sheet.
Ordering Information/Selector Guide
DRIVERS/
RECEIVERS
MAXIMUM
DATA RATE
TEMP RANGE
PIN-PACKAGE
MAX13234EEUP+
2x2
250kbps
-40°C to +85°C
20 TSSOP
MAX13234EETP+
2x2
250kbps
-40°C to +85°C
20 TQFN-EP*
MAX13235EEUP+
2x2
3Mbps
-40°C to +85°C
20 TSSOP
PART
MAX13235EETP+
2x2
3Mbps
-40°C to +85°C
20 TQFN-EP*
MAX13236EETE+
1x1
250kbps
-40°C to +85°C
16 TQFN-EP*
MAX13237EETE+
1x1
3Mbps
-40°C to +85°C
16 TQFN-EP*
+Denotes a lead-free/RoHS-compliant package.
*EP = Exposed pad.
19-4343; Rev 1; 12/14
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Absolute Maximum Ratings
(All voltages referenced to GND.)
VCC ...................................................................... -0.3V to +6.0V
VL ......................................................................... -0.3V to +6.0V
V+ ........................................................................ -0.3V to +7.0V
V- ......................................................................... +0.3V to -7.0V
(V+) + |(V-)| ..................................................................... +13.0V
T_IN, FORCEOFF, FORCEON ..................... -0.3V to (VL + 0.3V)
R_IN ................................................................................... ±25V
T_OUT.............................................................................. ±13.2V
R_OUT, READY ........................................... -0.3V to (VL + 0.3V)
Short-Circuit Duration
T_OUT to GND ......................................................... Continuous
Continuous Power Dissipation (TA = +70°C)
16-Pin TQFN (derate 20.8mW/°C above +70°C) ..... 1666mW
20-Pn TSSOP (derate 10.9mW/°C above +70°C) ...... 879mW
20-Pin TQFN (derate 21.3mW/°C above +70°C) ..... 1702mW
Junction-to-Case Thermal Resistance (θJC) (Note 1)
16-Pin TQFN ................................................................. 2°C/W
20-Pin TSSOP ............................................................. 20°C/W
20-Pin TQFN ................................................................. 2°C/W
Junction-to-Ambient Thermal Resistance (θJA) (Note 1)
16-Pin TQFN ............................................................... 30°C/W
20-Pin TSSOP ............................................................. 73°C/W
20-Pin TQFN ............................................................... 29°C/W
Operating Temperature Range
MAX1323x Operating Temperature Range .... -40°C to +85°C
MAX1323x Operating Temperature Range .. -40°C to +105°C
Storage Temperature Range ........................... -65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300ºC
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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.
Electrical Characteristics
(VCC = +3V to +5.5V, VL = +1.62V to VCC, TA = -40°C to +85°C, C1–C4 = 0.1µF, VCC = VL, tested at 3.3V ±10%. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER
Supply Voltage
Logic Supply Voltage
SYMBOL
MAX
UNITS
VCC
CONDITIONS
MIN
3
5.5
V
VL
1.62
VCC
V
mA
FORCEOFF = FORCEON = VL, no loads
VCC Supply Current
VCC Shutdown Current
VL Supply Current
VL Shutdown Current
ICC
ICCSH
IL
ILSH
TYP
0.3
1
VL = 0V
1
10
AutoShutDown Plus, FORCEOFF = VL,
FORCEON = GND, all R_IN idle, all T_IN
idle.
1
10
µA
FORCEOFF = GND
1
10
µA
VCC = +5.5V
1
10
µA
FORCEOFF = GND
1
10
µA
1/3 x VL
V
LOGIC INPUTS (T_IN, FORCEON, FORCEOFF, Referred to VL)
Input Threshold Low
VIL
Tested at room temperature only
Input Threshold High
VIH
Tested at room temperature only
Input Hysteresis
2/3 x VL
V
60
Input Leakage Current
±0.01
mV
±1
µA
0.4
V
RECEIVER OUTPUTS (READY)
Output-Voltage Low
VOL
IOUT = 0.8mA
Output-Voltage High
VOH
IOUT = -0.5mA
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VL - 0.6 VL - 0.1
V
Maxim Integrated | 2
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Electrical Characteristics (continued)
(VCC = +3V to +5.5V, VL = +1.62V to VCC, TA = -40°C to +85°C, C1–C4 = 0.1µF, VCC = VL, tested at 3.3V ±10%. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
+25
V
RECEIVER INPUTS
Input-Voltage Range
-25
Input Threshold Low
VIL
TA = +25°C
Input Threshold High
VIH
TA = +25°C
VCC = +3.3V
0.6
1.2
VCC = +5V
0.8
1.5
V
VCC = +3.3V
1.5
2.4
VCC = +5V
1.8
2.4
Input Hysteresis
0.5
Input Resistance
3
5
V
V
7
kΩ
TRANSMITTER OUTPUTS
Output-Voltage Swing
All transmitter outputs loaded with 3kΩ to
GND
±5
±5.4
V
Output Resistance
VCC = V+ = V- = 0V, transmitter outputs =
±2V
300
10M
Ω
Output Short-Circuit Current
VCC = 0V or +3V to +5.5V, VOUT = ±12V,
transmitters disabled
Output Leakage Current
-60
+60
mA
-25
+25
µA
2.7
V
AutoShutdown Plus (FORCEON = GND, FORCEOFF = VL)
Positive threshold, Figure 1
Receiver Input Threshold Valid
Level
Receiver Input Threshold
Invalid Level
Receiver or Transmitter Edge-toTransmitters Enabled
Receiver or Transmitter Edge-toTransmitters Shutdown
tWU
Negative threshold, Figure 1
-2.7
Figure 1
-0.3
VL = 5V, Figure 1 (Note 3)
tAUTOSHDN VL = 5V, Figure 1 (Note 3)
V
+0.3
100
15
30
V
µs
60
s
TIMING CHARACTERISTICS (MAX13234E/MAX13236E)
RL = 3kΩ, CL = 1000pF, one transmitter
switching
Maximum Data Rate
250
kbps
Receiver Propagation Delay
tRPHL,
tRPLH
CL = 150pF, Figures 2, 3
0.15
µs
Transmitter Skew
|tTPHL tTPLH|
Figures 4, 5 (Note 4)
100
ns
Receiver Skew
|tRPHL tRPLH|
Figures 2, 3
50
ns
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Maxim Integrated | 3
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Electrical Characteristics (continued)
(VCC = +3V to +5.5V, VL = +1.62V to VCC, TA = -40°C to +85°C, C1–C4 = 0.1µF, VCC = VL, tested at 3.3V ±10%. Typical values are
at TA = +25°C.) (Note 2)
PARAMETER
SYMBOL
Transition-Region Slew Rate
CONDITIONS
MIN
VCC = +3.3V, TA = +25°C, RL = 3kΩ to 7kΩ,
measured from +3V to -3V or -3V to +3V,
one transmitter switching, CL = 150pF to
1000pF
6
TYP
MAX
UNITS
30
V/µs
TIMING CHARACTERISTICS (MAX13235E/MAX13237E)
Maximum Data Rate
Receiver Propagation Delay
tRPHL,
tRPLH
RL = 3kΩ, CL = 250pF, one transmitter
switching
1
RL = 3kΩ, CL = 150pF, one transmitter
switching
3
Mbps
CL = 150pF, Figures 2, 3
0.15
µs
Transmitter Skew
|tTPHL –
tTPLH|
Figures 4, 5 (Note 4)
25
ns
Receiver Skew
|tRPHL –
tRPLH|
Figures 2, 3
50
ns
Transition-Region Slew Rate
VCC = +3.3V, TA = +25°C, RL = 3kΩ to 7kΩ,
measured from T_OUT = +3V to -3V or -3V
to +3V, one transmitter switching, CL =
150pF to 1000pF
24
150
V/µs
ESD PROTECTION
R_IN, T_OUT to GND
Human Body Model
±15
IEC 61000-4-2 Air Discharge
±15
IEC 61000-4-2 Contact Discharge
±8
kV
Note 2: All devices are 100% production tested at TA = +85°C. All temperature limits are guaranteed by design.
Note 3: A transmitter/receiver edge is defined as a transition through the transmitter/receiver input-logic thresholds.
Note 4: Transmitter skew is measured at the transmitter zero cross points.
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Maxim Integrated | 4
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Test Circuits/Timing Diagram
RECEIVER
INPUTS
TRANSMITTER
INPUTS
TRANSMITTER
OUTPUTS
tAUTOSHDN
VCC
READY
tWU
tAUTOSHDN
tWU
0
V+
V+
VCC
0
VV-
Figure 1. AutoShutdown Plus, and READY Timing Diagram
T_IN
T_OUT R_IN
R_OUT
CL
Figure 2. Receiver Test Circuit
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Maxim Integrated | 5
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Test Circuits/Timing Diagram (continued)
R_IN
tR, tF ≤ 10ns
1.3V
tRPHL
1.7V
tRPLH
VOH
R_OUT
VOL
VL/2
VL/2
Figure 3. Receiver Propagation Delay
T_IN
T_OUT
VO
RL
CL
Figure 4. Transmitter Test Circuit
VL
tR, tF ≤ 10ns
VL/2
T_IN
0
VL/2
tTPHL
tTPLH
VO
3V
3V
0
0
T_OUT
-3V
-3V
-VO
tF
SRF = 6/tF
SRR = 6/tR
tR
Figure 5. Transmitter Propagation Delay
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Maxim Integrated | 6
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Typical Operating Characteristics
(VCC = VL = 3.3V, TA = +25°C, unless otherwise noted.)
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
0
MAX13234E/MAX13236E
RL = 3kΩ
T1 AT 250kbps
-2
MAX13234E toc02
2
0
MAX13235E/MAX13237E
RL = 3kΩ
T1 AT 3Mbps
-2
12
MAX13234E/MAX13236E
RL = 3kΩ
11
10
SLEW RATE (V/μs)
OUTPUT VOLTAGE (V)
2
V+
4
OUTPUT VOLTAGE (V)
V+
4
SLEW RATE vs. LOAD CAPACITANCE
6
MAX13234E toc01
6
9
MAX13234E toc03
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
SR+
8
7
SR-
6
-4
V-
-6
500
1000
1500
2000
2500
50
100
150
200
250
0
300
2000
SLEW RATE vs. LOAD CAPACITANCE
VCC SUPPLY CURRENT
vs. LOAD CAPACITANCE
VCC SUPPLY CURRENT
vs. LOAD CAPACITANCE
SR+
50
20
15
10
100
150
200
250
30
25
20
15
5
0
300
MAX13235E
10
0
40
RL = 3kΩ
T1 AT 3Mbps
T2 AT 187.5kbps
35
5
45
500
1000
1500
2000
50
2500
100
150
200
250
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
TRANSMITTER SKEW
vs. LOAD CAPACITANCE
TRANSMITTER SKEW
vs. LOAD CAPACITANCE
READY TURN-ON TIME
vs. TEMPERATURE
70
50
30
7
6
5
4
3
2
100
300
MAX13234E toc09
MAX13235E/MAX13237E
RL = 3kΩ
1 TRANSMITTER
OPERATING AT 3Mbps
8
90
READY TURN-ON TIME (μs)
90
9
MAX13234E toc08
MAX13234E/MAX13236E
RL = 3kΩ
1 TRANSMITTER
OPERATING AT 250kbps
TRANSMITTER SKEW (ns)
MAX13234E toc07
150
2500
40
MAX13234E toc05
MAX13234E
SUPPLY CURRENT (mA)
60
RL = 3kΩ
T1 AT 250kbps
T2 AT 15.6kbps
25
SUPPLY CURRENT (mA)
SR-
55
30
MAX13234E toc04
65
110
1500
LOAD CAPACITANCE (pF)
70
130
1000
LOAD CAPACITANCE (pF)
MAX13235E/MAX13237E
RL = 3kΩ
50
500
LOAD CAPACITANCE (pF)
75
SLEW RATE (V/μs)
4
-6
0
TRANSMITTER SKEW (ns)
5
V-
MAX13234E toc06
-4
80
70
60
50
10
1
-10
0
0
500
1000
1500
2000
LOAD CAPACITANCE (pF)
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2500
40
50
100
150
200
LOAD CAPACITANCE (pF)
250
-40
-15
10
35
60
85
TEMPERATURE (°C)
Maxim Integrated | 7
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Typical Operating Characteristics (continued)
(VCC = VL = 3.3V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. DATA RATE
1.2
1.0
0.8
0.6
25
MAX13235E
1 TRANSMITTER
OPERATING
RL = 3kΩ, CL = 150pF
20
15
10
0.4
2.5
2.1
0
1.7
1.5
-15
10
35
60
1.1
0.9
0.7
0
0.001
85
0.5
0.01
TEMPERATURE (°C)
0.1
1
V+
4
MAX13235E/MAX13237E
RL = 3kΩ, CL = 150pF
1 TRANSMITTER
OPERATING AT 1Mbps
-4
6
V+
4
4.5
5.5
2
1 TRANSMITTER
OPERATING, DC
0
-2
-4
V-
-6
V-
-6
-8
-8
3.0
3.5
4.0
4.5
SUPPLY COLTAGE (V)
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3.5
VL (V)
8
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
6
-2
2.5
1.5
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX13234E toc13
8
0
10
DATA RATE (kbps)
TRANSMITTER OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
2
VIL
1.3
MAX13234E toc14
-40
VIH
1.9
5
0.2
VCC = 5.5V
2.3
LOGIC-INPUT THRESHOLD (V)
1.4
MAX13234E toc11
1.6
30
SUPPLY CURRENT (mA)
READY TURN-OFF TIME (μs)
1.8
LOGIC-INPUT THRESHOLD vs. VL
35
MAX13234E toc10
2.0
MAX13234E toc12
READY TURN-OFF TIME
vs. TEMPERATURE
5.0
5.5
0
2
4
6
8
LOAD CURRENT (mA)
Maxim Integrated | 8
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Pin Descriptions
PIN
MAX13234E/
MAX13235E
MAX13236E/
MAX13237E
NAME
FUNCTION
TSSOP
TQFN-EP
TQFN-EP
1
19
14
READY
2
1
16
C1+
3
20
15
V+
+5.5V Generated by the Charge Pump
4
2
1
C1-
Negative Terminal of the Voltage Doubler Charge-Pump
Capacitor
5
3
2
C2+
Positive Terminal of the Inverting Charge-Pump Capacitor
6
4
3
C2-
Negative Terminal of the Inverting Charge-Pump Capacitor
7
5
4
V-
8
6
—
T2OUT
—
—
5
RIN
RS-232 Receiver Input
Ready to Transmit Output, Active-High. READY is enabled
high when V- goes below -4V and the device is ready to
transmit.
Positive Terminal of the Voltage Doubler Charge-Pump
Capacitor
-5.5V Generated by the Charge Pump
RS-232 Transmitter Output 2
9
7
—
R2IN
RS-232 Receiver Input 2
—
—
6
ROUT
CMOS Receiver Output. VL referred logic.
10
8
—
R2OUT
CMOS Receiver Output 2. VL referred logic.
11
9
7
VL
Logic-Level Supply. All CMOS inputs and outputs are related
to this supply.
—
—
8
TIN
CMOS Transmitter Input. VL referred logic.
12
10
—
T2IN
CMOS Transmitter Input 2. VL referred logic.
13
11
—
T1IN
CMOS Transmitter Input 1. VL referred logic.
14
12
9
FORCEON
15
13
—
R1OUT
FORCEON Input, Active-High. VL referenced logic. Drive
FORCEON high to override automatic circuitry keeping
transmitters on (FORCEOFF must be high).
See Table 1.
CMOS Receiver Output 1. VL referred logic.
—
—
10
TOUT
RS-232 Transmitter Output
16
14
—
R1IN
RS-232 Receiver Input 1
17
15
—
T1OUT
18
16
11
GND
Ground
19
17
12
VCC
+3V to +5.5V Supply Voltage
20
18
13
FORCEOFF
—
—
—
EP
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RS-232 Transmitter Output 1
FORCEOFF Input, Active-Low. VL referenced logic. Drive
FORCEOFF low to shut down transmitters and on-board
charge pumps. All receiver and transmitter outputs are tristated. This overrides all automatic circuitry and FORCEON
(Table 1).
Exposed Pad. Connect EP to GND or leave unconnected.
Maxim Integrated | 9
MAX13234E–MAX13237E
Detailed Description
VL Logic Supply Input
The MAX13234E–MAX13237E feature a separate logic
supply input (VL) that sets the receiver’s output level
(VOH), and sets the transmitter’s input thresholds (VIL,
V IH ). This feature allows flexibility in interfacing to
UARTs or communication controllers that have different
logic levels. Connect this input to the host logic supply
(1.62V ≤ VL ≤ VCC).
Dual Charge-Pump Voltage Converter
The internal power supply consists of a regulated dual
charge pump that provides output voltages of +5.5V
and -5.5V (inverting charge pump), over the +3.0V to
+5.5V range. The charge pump operates in discontinuous 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. The
charge pumps require flying capacitors (C1, C2) and
reservoir capacitors (C3, C4) to generate the V+ and Vsupplies. The READY output is low when the charge
pumps are disabled in shutdown mode. The READY
signal asserts high when V- goes below -4V.
RS-232 Transmitters
The transmitters are inverting level translators that convert CMOS-logic levels to ±5.0V EIA/TIA-232 levels.
The MAX13234E/MAX13236E guarantee a 250kbps
data rate with worst-case loads of 3kΩ in parallel with
1000pF. The MAX13235E/MAX13237E guarantee a
1Mbps data rate with worst-case loads of 3kΩ in parallel with 250pF, and a 3Mbps data rate with worst-case
loads of 3kΩ in parallel with 150pF. Transmitters can be
paralleled to drive multiple receivers. When FORCEOFF
is driven to ground or when the AutoShutdown Plus circuitry senses that all receiver and transmitter inputs are
inactive for more than 30s, 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 pullup resistors. Connect unused inputs to GND or VL.
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
RS-232 Receivers
The receivers convert RS-232 signals to CMOS-logic
output levels. The MAX13234E–MAX13237E have
inverting outputs that are active when in shutdown
(FORCEOFF = GND) (Table 1).
AutoShutdown Plus Mode
Drive FORCEOFF high and FORCEON low to invoke
AutoShutdown Plus mode. When these devices do not
sense a valid signal transition on any receiver and
transmitter input for 30s, the onboard charge pumps
are shut down, reducing supply current to 1µA. This
occurs if the RS-232 cable is disconnected or
if the devices driving the transmitter and receiver
inputs are inactive for more than 30s. The
MAX13234E–MAX13237E turn on again when a valid
transition is applied to any RS-232 receiver or transmitter input. As a result, the system saves power without
requiring any control.
Figure 6 and Table 1 summarize the MAX13234E–
MAX13237E operating modes. The FORCEON and
FORCEOFF inputs override AutoShutdown Plus circuitry. When neither control is asserted, the IC selects
between these states automatically based on the last
receiver or transmitter input edge received.
Hardware-Controlled Shutdown
Drive FORCEOFF low to place the MAX13234E–
MAX13237E into shutdown mode.
POWERMANAGEMENT
UNIT
MASTER SHDN LINE
0.1μF
1MΩ
FORCEOFF FORCEON
MAX13234E
MAX13235E
MAX13236E
MAX13237E
Figure 7. AutoShutdown Plus Initial Turn-On to Wake Up a
Mouse or Another System
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Maxim Integrated | 10
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
T_IN
R_IN
EDGE
DETECT
EDGE
DETECT
FORCEOFF
FORCEOFF
S
30s
TIMER
AUTOSHDN
POWERDOWN*
FORCEON
R
* POWERDOWN IS ONLY AN INTERNAL SIGNAL.
IT CONTROLS THE OPERATIONAL STATUS OF
THE TRANSMITTERS AND THE POWER SUPPLIES.
FORCEON
Figure 6. AutoShutdown Plus and Shutdown Logic
Table 1. Transceiver Mode Control
R_IN or T_IN
EDGE WITHIN 30s
T_OUT
X
X
High-Impedance
Active
Shutdown (Forced Off)
1
X
Active
Active
Normal Operation (Forced On)
1
0
Yes
Active
Active
Normal Operation in AutoShutdown Plus
1
0
No
High-Impedance
Active
Shutdown in AutoShutdown Plus
FORCEOFF
FORCEON
0
1
R_OUT
TRANSCEIVER STATUS
X = Don’t Care.
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Maxim Integrated | 11
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
±15kV ESD Protection
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 MAX13234E–MAX13237E 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 powered down. After
RC
1MΩ
CHARGE-CURRENT
LIMIT RESISTOR
HIGHVOLTAGE
DC
SOURCE
Cs
100pF
an ESD event, Maxim’s E versions keep working without
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) ±15V Using the Human Body Model
2) ±15kV Using IEC 61000-4-2 Air-Gap Method
3) ±8kV Using IEC 61000-4-2 Contact-Discharge
Method
RC
50MΩ to 100MΩ
RD
1500Ω
DISCHARGE
RESISTANCE
CHARGE-CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
DEVICE
UNDER
TEST
STORAGE
CAPACITOR
Figure 8a. Human Body ESD Test Model
HIGHVOLTAGE
DC
SOURCE
RD
330Ω
Cs
150pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 9a. IEC61000-4-2 ESD Test Model
I
IP 100%
90%
Ir
100%
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
90%
I PEAK
AMPERES
36.8%
10%
0
0
tRL
TIME
tDL
CURRENT WAVEFORM
Figure 8b. Human Body Current Waveform
10%
t r = 0.7ns to 1ns
t
30ns
60ns
Figure 9b. IEC61000-4-2 ESD Generator Current Waveform
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Maxim Integrated | 12
MAX13234E–MAX13237E
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 8a shows the Human Body Model and Figure 8b
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, which is then discharged into the test device
through a 1.5kΩ resistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment; it does not specifically refer to integrated circuits. The MAX13234E–
MAX13237E helps design equipment that meets Level
4 (the highest level) of IEC 61000-4-2, without the need
for additional ESD-protection components. The major
difference between tests done using the Human Body
Model and IEC 61000-4-2 is higher peak current in IEC
61000-4-2, because series resistance is lower in the
IEC 61000-4-2 model. Hence, the ESD withstand voltage measured to IEC 61000-4-2 is generally lower than
that measured using the Human Body Model. Figure 9a
shows the IEC 61000-4-2 model and Figure 9b shows
the current waveform for the 8kV, IEC 61000-4-2, Level
4, ESD Contact-Discharge Method.
The Air-Gap Method involves approaching the device
with a charged probe. The Contact-Discharge Method
connects the probe to the device before the probe is
energized.
Applications Information
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
larger nominal value. The capacitor’s equivalent series
resistance (ESR), usually rises at low temperatures
influencing the amount of ripple on V+ and V-.
Table 2. Required Minimum
Capacitance Values
VCC
(V)
C1, CBYPASS2
(µF)
CBYPASS1
(µF)
C2, C3, C4
(µF)
3.0 to 3.6
0.22
0.22
0.22
3.15 to 3.6
0.1
0.1
0.1
4.5 to 5.5
0.047
1
0.33
3.0 to 5.5
0.22
1
1
Power-Supply Decoupling
In most circumstances, a 0.1µF VCC bypass capacitor
and a 1µF VL bypass capacitor are adequate. In applications that are sensitive to power-supply noise, use
capacitors of the same value as charge-pump capacitor C1. Connect bypass capacitors as close to the IC
as possible.
Transmitter Outputs when Exiting
Shutdown
Figure 10 shows two transmitter outputs when exiting
shutdown mode. As they become active, the two transmitter outputs are shown going to opposite RS-232 levels (one transmitter input is high, the other is low). 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.
Capacitor Selection
The capacitor type used for C1–C4 is not critical for
proper operation; polarized or non-polarized capacitors
can be used. The charge pump requires 0.1µF capacitors for VCC = +3.3V operation. For other supply voltages, see Table 2 for required capacitor values. Do not
use values smaller than those listed in Table 2.
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, C4, CBYPASS1, and CBYPASS2 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
www.maximintegrated.com
5V/div
0
FORCEON = FORCEOFF
T1OUT
2V/div
0
5V/div
0
T2OUT
VCC = 3.3V
C1–C4 = 0.1μF
READY
5μs/div
Figure 10. Transmitter Outputs when Exiting Shutdown or
Powering Up
Maxim Integrated | 13
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
High Data Rates
The MAX13234E–MAX13237E maintain the RS-232 ±5V
minimum transmitter output voltage even at high data
rates. Figure 11 shows a transmitter loopback test circuit. Figure 12 shows a loopback test result at
120kbps, and Figure 13 shows the same test at 3Mbps.
1.62V to VCC
In Figure 12, all transmitters were driven simultaneously
at 120kbps into RS-232 loads in parallel with 1000pF.
In Figure 13, a single transmitter was driven at 3Mbps,
and all transmitters were loaded with an RS-232 receiver in parallel with 150pF.
VCC
3V/div
T1IN
CBYPASS2
CBYPASS1
VL
5V/div
VCC
T1OUT
C1+
V+
C1
C3*
C1C2+
5V/div
R1OUT
MAX13236E
MAX13237E
VCC = 3.3V
V-
C2
C4
2μs/div
C2-
R_IN
R_OUT
FORCEON
VCC
Figure 12. Loopback Test Results at 120kbps
T_OUT
T_IN
5kΩ
1000pF
3.3V/div
T1IN
FORCEOFF
T1OUT
GND
5V/div
*C3 CAN BE RETURNED TO VCC OR GND.
3.3V/div
R1OUT
VCC = 3.3V
Figure 11. Loopback Test Circuit
100ns/div
Figure 13. Loopback Test Results at 3Mbps
Chip Information
PROCESS: BiCMOS
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Maxim Integrated | 14
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Pin Configurations
TOP VIEW
13
12
11
GND
T1OUT
16
R1IN
C2-
6
15
R1OUT
V-
7
14
FORCEON
T2OUT
8
13
T1IN
R2IN
9
12
T2IN
R2OUT
10
11
VL
VCC
17
FORCEOFF
18
READY
19
V+
20
MAX13234E
MAX13235E
*EP
+
1
2
TSSOP
3
4
5
V-
17
C2-
MAX13234E
MAX13235E
C2+
5
C1-
4
16
C1+
C1C2+
GND
10
T2IN
9
VL
8
R2OUT
7
R2IN
6
FORCEON
14
18
12
11
10
9
FORCEOFF
13
8
TIN
READY
14
7
VL
V+
15
6
ROUT
C1+
16
5
RIN
T2OUT
TQFN
MAX13236E
MAX13237E
*EP
+
1
2
3
4
V-
T1IN
15
3
TOUT
FORCEON
VCC
V+
GND
R1OUT
19
C2-
FORCEOFF
2
C2+
20
C1+
+
VCC
1
C1-
READY
R1IN
TOP VIEW
T1OUT
TOP VIEW
TQFN
*EXPOSED PAD. CONNECT EP TO GND.
*EXPOSED PAD. CONNECT EP TO GND.
Functional Diagrams (continued)
1.62V to VCC
3.0V to 5.5V
CBYPASS2
CBYPASS1
VL
VCC
C1+
V+
C1
C3
C1-
MAX13236E
MAX13237E
C2+
V-
C2
C4
C2T_IN
TTL/CMOS
OUTPUT
R_OUT
FORCEOFF
FORCEON
T_OUT
LOGIC-LEVEL TRANSLATION
TTL/CMOS
INPUT
R_IN
RS-232
OUTPUT
RS-232
INPUT
5kΩ
READY
GND
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Maxim Integrated | 15
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
MAX13234E–MAX13237E
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
20 TSSOP
U20-2
21-0066
20 TQFN-EP*
T2055-5
21-0140
16 TQFN-EP*
T1655-2
21-0140
*EP = Exposed Pad.
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Maxim Integrated | 16
MAX13234E–MAX13237E
3Mbps RS-232 Transceivers with
Low-Voltage Interface, ±15kV
HBM ESD
Revision History
REVISION
NUMBER
REVISION
DATE
0
10/08
Initial release
—
1
12/14
Updated General Description and Benefits and Features sections
1
DESCRIPTION
PAGES
CHANGED
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2014 Maxim Integrated Products, Inc. | 17
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