MAXIM MAX3232CSE

19-0273; Rev 5; 3/99
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
____________________________Features
The MAX3222/MAX3232/MAX3237/MAX3241 transceivers have a proprietary low-dropout transmitter output stage enabling true RS-232 performance from a
3.0V to 5.5V supply with a dual charge pump. The
devices require only four small 0.1µF external chargepump capacitors. The MAX3222, MAX3232, and
MAX3241 are guaranteed to run at data rates of
120kbps while maintaining RS-232 output levels. The
MAX3237 is guaranteed to run at data rates of 250kbps
in the normal operating mode and 1Mbps in the
MegaBaud™ operating mode, while maintaining RS-232
output levels.
♦ Low Supply Current:
300µA (MAX3222/MAX3232/MAX3241)
500µA (MAX3237)
♦ Guaranteed Data Rate:
120kbps (MAX3222/MAX3232/MAX3241)
250kbps (MAX3237—Normal Operation)
1Mbps (MAX3237—MegaBaud Operation)
♦ 1µA Low-Power Shutdown with Receivers Active
(MAX3222/MAX3237/MAX3241)
♦ Flow-Through Pinout (MAX3237)
♦ Meets EIA/TIA-232 Specifications Down to 3.0V
♦ Guaranteed Mouse Driveability (MAX3241)
♦ Pin Compatible with Industry-Standard MAX232
(MAX3232)
Pin Compatible with Industry-Standard MAX242
(MAX3222)
♦ Guaranteed Slew Rate:
6V/µs (MAX3222/MAX3232/MAX3237/MAX3241)
24V/µs (MAX3237—MegaBaud Operation)
The MAX3222/MAX3232 have 2 receivers and 2
drivers. The MAX3222 features a 1µA shutdown mode
that reduces power consumption and extends battery
life in portable systems. Its receivers remain active in
shutdown mode, allowing external devices such as
modems to be monitored using only 1µA supply current. The MAX3222 and MAX3232 are pin, package,
and functionally compatible with the industry-standard
MAX242 and MAX232, respectively.
The MAX3241 is a complete serial port (3 drivers/
5 receivers) designed for notebook and subnotebook
computers. The MAX3237 (5 drivers/3 receivers) is ideal
for fast modem applications. Both these devices feature
a shutdown mode in which all receivers can remain
active while using only 1µA supply current. Receivers R1
(MAX3237/MAX3241) and R2 (MAX3241) have extra outputs in addition to their standard outputs. These extra
outputs are always active, allowing external devices
such as a modem to be monitored without forward biasing the protection diodes in circuitry that may have VCC
completely removed.
The MAX3222, MAX3237, and MAX3241 are available
in space-saving TSSOP and SSOP packages.
________________________Applications
Notebook, Subnotebook, and Palmtop Computers
High-Speed Modems
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Printers
Typical Operating Circuits appear at end of data sheet.
______________Ordering Information
PART
MAX3222CUP
MAX3222CAP
MAX3222CWN
TEMP. RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
MAX3222CPN
0°C to +70°C
PIN-PACKAGE
20 TSSOP
20 SSOP
18 SO
18 Plastic DIP
Ordering Information continued at end of data sheet.
_________________Pin Configurations
TOP VIEW
EN 1
18 SHDN
C1+ 2
17 VCC
V+ 3
16 GND
15 T1OUT
C1- 4
C2+ 5
C2-
6
MAX3222
14 R1IN
13 R1OUT
V-
7
12 T1IN
T2OUT
8
11 T2IN
R2IN
9
10 R2OUT
DIP/SO
Pin Configurations continued at end of data sheet.
MegaBaud is a trademark of Maxim Integrated Products.
*Covered by U.S. Patent numbers 4,636,930; 4,679,134; 4,777,577; 4,797,899; 4,809,152; 4,897,774; 4,999,761; and other patents pending.
________________________________________________________________ Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX3222/MAX3232/MAX3237/MAX3241*
_______________General Description
MAX3222/MAX3232/MAX3237/MAX3241
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
ABSOLUTE MAXIMUM RATINGS
Continuous Power Dissipation (TA = +70°C)
16-Pin Plastic DIP (derate 10.53mW/°C above +70°C)...842mW
16-Pin Narrow SO (derate 8.70mW/°C above +70°C) ....696mW
16-Pin Wide SO (derate 9.52mW/°C above +70°C)........762mW
16-Pin TSSOP (derate 6.7mW/°C above +70°C).............533mW
18-Pin Plastic DIP (derate 11.11mW/°C above +70°C) ..889mW
18-Pin SO (derate 9.52mW/°C above +70°C)..............762mW
20-Pin SSOP (derate 8.00mW/°C above +70°C) .........640mW
20-Pin TSSOP (derate 7.0mW/°C above +70°C).............559mW
28-Pin SO (derate 12.50mW/°C above +70°C) .....................1W
28-Pin SSOP (derate 9.52mW/°C above +70°C) .........762mW
28-Pin TSSOP (derate 8.7mW/°C above +70°C).............696mW
Operating Temperature Ranges
MAX32_ _C_ _.....................................................0°C to +70°C
MAX32_ _E_ _ .................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
VCC ...........................................................................-0.3V to +6V
V+ (Note 1) ...............................................................-0.3V to +7V
V- (Note 1) ................................................................+0.3V to -7V
V+ + V- (Note 1)...................................................................+13V
Input Voltages
T_IN, SHDN, EN ...................................................-0.3V to +6V
MBAUD...................................................-0.3V to (VCC + 0.3V)
R_IN .................................................................................±25V
Output Voltages
T_OUT...........................................................................±13.2V
R_OUT ....................................................-0.3V to (VCC + 0.3V)
Short-Circuit Duration
T_OUT ....................................................................Continuous
Note 1: V+ and V- can have a maximum magnitude 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.
ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
UNITS
TYP
MAX
MAX3222/MAX3232/
MAX3241
0.3
1.0
MAX3237
0.5
2.0
1.0
10
µA
0.8
V
DC CHARACTERISTICS
VCC Power-Supply Current
Shutdown Supply Current
No load, VCC = 3.3V or 5.0V,
TA = +25°C
SHDN = GND, TA = +25°C
mA
LOGIC INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
(Note 3)
T_IN, EN, SHDN, MBAUD
Input Logic Threshold High
(Note 3)
VCC = 3.3V
2.0
VCC = 5.0V
2.4
Input Leakage Current
T_IN, EN, SHDN, MBAUD
±0.01
±1.0
µA
Output Leakage Current
Receivers disabled
±0.05
±10
µA
Output Voltage Low
IOUT = 1.6mA
0.4
V
Output Voltage High
IOUT = -1.0mA
VCC - 0.6
V
VCC - 0.1
V
RECEIVER INPUTS
Input Voltage Range
-25
Input Threshold Low
TA = +25°C
Input Threshold High
TA = +25°C
VCC = 5.0V
2
25
VCC = 3.3V
0.6
1.2
VCC = 5.0V
0.8
1.5
V
VCC = 3.3V
1.5
2.4
VCC = 5.0V
1.8
2.4
_______________________________________________________________________________________
V
V
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
Input Hysteresis
TYP
MAX
UNITS
0.3
Input Resistance
TA = +25°C
3
5
V
7
kΩ
TRANSMITTER OUTPUTS
Output Voltage Swing
All transmitter outputs loaded with 3kΩ to ground
±5.0
±5.4
Output Resistance
VCC = V+ = V- = 0V, TOUT = ±2V
300
10M
Output Short-Circuit Current
Output Leakage Current
±35
VOUT = ±12V, VCC = 0V or 3V to 5.5V, transmitters
disabled
V
Ω
±60
mA
±25
µA
MOUSE DRIVEABILITY (MAX3241)
Transmitter Output Voltage
T1IN = T2IN = GND, T3IN = VCC,
T3OUT loaded with 3kΩ to GND,
T1OUT and T2OUT loaded with 2.5mA each
±5.0
V
TIMING CHARACTERISTICS—MAX3222/MAX3232/MAX3241
(VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Maximum Data Rate
CONDITIONS
RL = 3kΩ, CL = 1000pF, one transmitter switching
MIN
TYP
120
235
tPHL
0.3
tPLH
0.3
MAX
UNITS
kbps
Receiver Propagation Delay
R_IN to R_OUT, CL = 150pF
Receiver Output Enable Time
Normal operation
200
ns
Receiver Output Disable Time Normal operation
200
ns
300
ns
300
ns
| tPHL - tPLH |
| tPHL - tPLH |
Transmitter Skew
Receiver Skew
Transition-Region Slew Rate
VCC = 3.3V, RL = 3Ω to 7kΩ,
+3V to -3V or -3V to +3V,
TA = +25°C
µs
CL = 150pF to
1000pF
6
30
CL = 150pF to
2500pF
4
30
V/µs
_______________________________________________________________________________________
3
TIMING CHARACTERISTICS—MAX3237
(VCC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
Maximum Data Rate
MIN
RL = 3kΩ, CL = 1000pF, one transmitter switching,
MBAUD = GND
250
VCC = 3.0V to 4.5V, RL = 3kΩ, CL = 250pF,
one transmitter switching, MBAUD = VCC
1000
VCC = 4.5V to 5.5V, RL = 3kΩ, CL = 1000pF,
one transmitter switching, MBAUD = VCC
1000
TYP
UNITS
MAX
kbps
tPHL
0.15
tPLH
0.15
Receiver Propagation Delay
R_IN to R_OUT, CL = 150pF
Receiver Output Enable Time
Normal operation
200
ns
Receiver Output Disable Time Normal operation
200
ns
100
ns
25
ns
50
ns
| tPHL - tPLH |, MBAUD = GND
| tPHL - tPLH |, MBAUD = VCC
| tPHL - tPLH |
Transmitter Skew
Receiver Skew
Transition-Region Slew Rate
VCC = 3.3V, RL = 3Ω to 7kΩ,
+3V to -3V or -3V to +3V,
TA = +25°C
CL = 150pF
to 1000pF
µs
MBAUD =
GND
6
30
MBAUD =
VCC
24
150
4
30
CL = 150pF to 2500pF,
MBAUD = GND
V/µs
Note 2: MAX3222/MAX3232/MAX3241: C1–C4 = 0.1µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested at 5.0V ±10%.
MAX3237: C1–C4 = 0.1µF tested at 3.3V ±5%; C1–C4 = 0.22µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested
at 5.0V ±10%.
Note 3: Transmitter input hysteresis is typically 250mV.
__________________________________________Typical Operating Characteristics
(VCC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, TA = +25°C, unless otherwise noted.)
0
-1
-2
-3
16
14
-SLEW
12
10
+SLEW
8
6
-4
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
25
120kbps
20
15
20kbps
10
5
2
0
0
30
4
VOUT-
-5
35
SUPPLY CURRENT (mA)
SLEW RATE (V/µs)
2
1
40
235kbps
18
-6
4
FOR DATA RATES UP TO 235kbps
20
MAX3222-03
4
3
22
MAX3222-02
VOUT+
MAX3222-01
6
5
MAX3222/MAX3232
SUPPLY CURRENT vs. LOAD CAPACITANCE
WHEN TRANSMITTING DATA
MAX3222/MAX3232
SLEW RATE
vs. LOAD CAPACITANCE
MAX3222/MAX3232
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3222/MAX3232/MAX3237/MAX3241
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
5000
0
150
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
5000
0
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
_______________________________________________________________________________________
5000
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
VOUT+
5.0
22
1 TRANSMITTER AT 235kbps
2 TRANSMITTERS AT 30kbps
0
-2.5
VOUT-
-5.0
-SLEW
16
14
12
+SLEW
10
8
ALL OUTPUTS LOADED WITH 3kΩ +CL
0.1µF CHARGE-PUMP CAPACITORS
FOR ALL DATA RATES UP TO 235kbps
6
4
-7.5
0
1000
2000
3000
4000
5000
0
1000
2000
3000
4000
35
30
120kbps
25
20
20kbps
15
10
5
0
1000
0
5000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3237
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE (MBAUD = GND)
MAX3237
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE (MBAUD = VCC)
MAX3237
SLEW RATE vs. LOAD CAPACITANCE
(MBAUD = GND)
-2.5
-5.0
-7.5
1.5Mbps
2.5
1 TRANSMITTER AT FULL DATA RATE
4 TRANSMITTERS AT 1/16 DATA RATE
3kΩ + CL LOAD, EACH OUTPUT
VCC = 3.3V
0
-2.5
1000
2000
3000
4000
6
4
0
0
0
500
1000
1500
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
1 TRANSMITTER AT FULL DATA RATE
4 TRANSMITTERS AT 1/16 DATA RATE
3kΩ + CL LOAD EACH OUTPUT
VCC = 3.3V
MAX3222-11
MAX3222-10
30
70
3000
4000
5000
1 TRANSMITTER AT 512kbps
4 TRANSMITTERS AT 32kbps
3kΩ + CL LOADS
VCC = 3.3V
MBAUD = VCC
60
50
120kbps
MAX
40
30
20kbps
AVERAGE; 10 PARTS
30
20
20
1 TRANSMITTER AT FULL DATA RATE
4 TRANSMITTERS AT 1/16 DATA RATE
3kΩ + CL LOADS
VCC = 3.3V
10
10
0
2000
2000
MAX3237
SKEW vs. LOAD CAPACITANCE
(tPLH - tPHL)
240kbps
40
1000
LOAD CAPACITANCE (pF)
60
50
0
2000
MAX3237
SUPPLY CURRENT vs.
LOAD CAPACITANCE (MBAUD = GND)
40
0
1500
MAX3237
SLEW RATE vs. LOAD CAPACITANCE
(MBAUD = VCC)
-SLEW, 1Mbps
+SLEW, 1Mbps
-SLEW, 2Mbps
+SLEW, 2Mbps
10
1000
LOAD CAPACITANCE (pF)
50
20
500
LOAD CAPACITANCE (pF)
60
1 TRANSMITTER AT 240kbps
4 TRANSMITTERS AT 15kbps
3kΩ + CL LOADS
VCC = 3.3V
2
1Mbps
5000
70
MAX3222-09
8
-7.5
0
-SLEW
+SLEW
1.5Mbps
2Mbps
-5.0
10
MAX3222-12
0
2Mbps
SKEW (ns)
1 TRANSMITTER AT 240kbps
4 TRANSMITTERS AT 15kbps
3kΩ + CL LOADS
VCC = 3.3V
5.0
12
SLEW RATE (V/µs)
2.5
1Mbps
MAX3222-08
5.0
7.5
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3222-07
7.5
TRANSMITTER OUTPUT VOLTAGE (V)
18
235kbps
40
SUPPLY CURRENT (mA)
SLEW RATE (V/µs)
20
2.5
45
MAX3222-05
24
MAX3222-04
TRANSMITTER OUTPUT VOLTAGE (V)
7.5
SLEW RATE (V/µs)
MAX3241
SUPPLY CURRENT vs. LOAD
CAPACITANCE WHEN TRANSMITTING DATA
MAX3241
SLEW RATE
vs. LOAD CAPACITANCE
MAX3222-06
MAX3241
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
0
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
5000
MIN
0
0
500
1000
1500
2000
2500
LOAD CAPACITANCE (pF)
_______________________________________________________________________________________
5
MAX3222/MAX3232/MAX3237/MAX3241
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, TA = +25°C, unless otherwise noted.)
MAX3222/MAX3232/MAX3237/MAX3241
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
______________________________________________________________Pin Description
PIN
NAME
MAX3222
6
MAX3232
MAX3237
MAX3241
FUNCTION
DIP/SO
SSOP
1
1
—
13
23
EN
2
2
1
28
28
C1+
3
3
2
27
27
V+
+5.5V Generated by the Charge Pump
4
4
3
25
24
C1-
Negative Terminal of Voltage-Doubler Charge-Pump
Capacitor
5
5
4
1
1
C2+
Positive Terminal of Inverting Charge-Pump
Capacitor
6
6
5
3
2
C2-
Negative Terminal of Inverting Charge-Pump
Capacitor
7
7
6
4
3
V-
8, 15
8, 17
7, 14
5, 6, 7,
10, 12
9, 10, 11
T_OUT
9, 14
9, 16
8, 13
8, 9, 11
4–8
R_IN
10, 13
10, 15
9, 12
18, 20, 21
15–19
R_OUT
TTL/CMOS Receiver Outputs
11, 12
12, 13
10, 11
17, 19, 22,
23, 24
12, 13, 14
T_IN
TTL/CMOS Transmitter Inputs
16
18
15
2
25
GND
Ground
17
19
16
26
26
VCC
+3.0V to +5.5V Supply Voltage
18
20
—
14
22
SHDN
Shutdown Control. Active low.
—
11, 14
—
—
—
N.C.
—
—
—
15
—
MBAUD
MegaBaud Control Input. Connect to GND for normal
operation; connect to VCC for 1Mbps transmission rates.
—
—
—
16
20, 21
R_OUTB
Noninverting Complementary Receiver Outputs.
Always active.
Receiver Enable. Active low.
Positive Terminal of Voltage-Doubler Charge-Pump
Capacitor
-5.5V Generated by the Charge Pump
RS-232 Transmitter Outputs
RS-232 Receiver Inputs
No Connection
_______________________________________________________________________________________
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
Dual Charge-Pump Voltage Converter
The MAX3222/MAX3232/MAX3237/MAX3241’s internal
power supply consists of a regulated dual charge pump
that provides output voltages of +5.5V (doubling charge
pump) and -5.5V (inverting charge pump), regardless of
the input voltage (VCC) over the 3.0V to 5.5V range. The
charge pumps operate in a discontinuous mode; if the
output voltages are less than 5.5V, the charge pumps
are enabled, and if the output voltages exceed 5.5V, 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- supplies.
RS-232 Transmitters
The transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels.
The MAX3222/MAX3232/MAX3241 transmitters guarantee a 120kbps data rate with worst-case loads of 3kΩ in
parallel with 1000pF, providing compatibility with PC-toPC communication software (such as LapLink™).
Typically, these three devices can operate at data rates
of 235kbps. Transmitters can be paralleled to drive multiple receivers or mice.
The MAX3222/MAX3237/MAX3241’s output stage is
turned off (high impedance) when the device is in shutdown mode. When the power is off, the MAX3222/
MAX3232/MAX3237/MAX3241 permit the outputs to be
driven up to ±12V.
The transmitter inputs do not have pull-up resistors.
Connect unused inputs to GND or VCC.
MAX3237 MegaBaud Operation
In normal operating mode (MBAUD = GND), the
MAX3237 transmitters guarantee a 250kbps data rate
with worst-case loads of 3kΩ in parallel with 1000pF.
This provides compatibility with PC-to-PC communication software, such as Laplink™.
For higher speed serial communications, the MAX3237
features MegaBaud operation. In MegaBaud operating
mode (MBAUD = VCC), the MAX3237 transmitters guarantee a 1Mbps data rate with worst-case loads of 3kΩ in
parallel with 250pF for 3.0V < VCC < 4.5V. For 5V ±10%
operation, the MAX3237 transmitters guarantee a 1Mbps
data rate into worst-case loads of 3kΩ in parallel with
1000pF.
LapLink is a trademark of Traveling Software.
VCC
VCC
0.1µF
0.1µF
VCC
C1+
C1+
V+
C1
C3
C1-
MAX3222
MAX3232
MAX3237
MAX3241
C2+
C2
C2-
C2+
VC2
C4
C2T_ OUT
T_ IN
0V
5k
GND
VC4
T_ OUT
R_ IN
R_ OUT
EN*
SHDN*
MAX3222
MAX3232
MAX3237
MAX3241
T_ IN
R_ IN
R_ OUT
VCC
V+
C1
C3
C1-
0V
VCC
3k
2500pF
VCC
EN*
5k
SHDN*
GND
7k
150pF
* MAX3222/MAX3241 ONLY
MINIMUM SLEW-RATE TEST CIRCUIT
MAXIMUM SLEW-RATE TEST CIRCUIT
Figure 1. Slew-Rate Test Circuits
_______________________________________________________________________________________
7
MAX3222/MAX3232/MAX3237/MAX3241
_______________Detailed Description
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
RS-232 Receivers
The receivers convert RS-232 signals to CMOS-logic output levels. The MAX3222/MAX3237/MAX3241 receivers
have inverting three-state outputs. In shutdown, the
receivers can be active or inactive (Table 1).
The complementary outputs on the MAX3237 (R1OUTB)
and the MAX3241 (R1OUTB, R2OUTB) are always active,
regardless of the state of EN or SHDN. This allows for
Ring Indicator applications without forward biasing other
devices connected to the receiver outputs. This is ideal
for systems where V CC is set to 0V in shutdown to
accommodate peripherals, such as UARTs (Figure 2).
VCC
PREVIOUS
RS-232
VCC
Rx
PROTECTION
DIODE
5k
MAX3222/MAX3237/MAX3241
Shutdown Mode
UART
Tx
GND
Supply current falls to less than 1µA in shutdown mode
(SHDN = low). When shut down, the device’s charge
pumps are turned off, V+ is pulled down to VCC, V- is
pulled to ground, and the transmitter outputs are disabled (high impedance). The time required to exit shutdown is typically 100µs, as shown in Figure 3. Connect
SHDN to VCC if the shutdown mode is not used. SHDN
has no effect on R_OUT or R_OUTB.
SHDN = GND
a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM
ACTIVE RECEIVER OUTPUT IN SHUTDOWN.
MAX3222/MAX3237/MAX3241
Enable Control
VCC
TO
µP
The inverting receiver outputs (R_OUT) are put into a
high-impedance state when EN is high. The complementary outputs R1OUTB and R2OUTB are always active,
regardless of the state of EN and SHDN (Table 1). EN
has no effect on T_OUT.
LOGIC
TRANSITION
DETECTOR
MAX3237
MAX3241
__________Applications Information
R1OUTB
Capacitor Selection
VCC
Rx
PROTECTION
DIODE
EN = VCC
UART
Tx
GND
R1IN
R1OUT
T1IN
5k
T1OUT
SHDN = GND
b) NEW MAX3237/MAX3241: EN SHUTS DOWN RECEIVER OUTPUTS (EXCEPT FOR
B OUTPUTS), SO NO CURRENT FLOWS TO UART IN SHUTDOWN. B OUTPUTS
INDICATE RECEIVER ACTIVITY DURING SHUTDOWN WITH EN HIGH.
Figure 2. Detection of RS-232 Activity when the UART and
Interface are Shut Down; Comparison of MAX3237/MAX3241
(b) with Previous Transceivers (a).
8
The capacitor type used for C1–C4 is not critical for
proper operation; polarized or nonpolarized capacitors
can be used. The charge pump requires 0.1µF capacitors for 3.3V operation. For other supply voltages, refer to
Table 2 for required capacitor values. Do not use values
lower 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, 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
higher nominal value. The capacitor’s equivalent series
resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-.
_______________________________________________________________________________________
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
R_OUT
R_OUTB
(MAX3237/
MAX3241)
High-Z
Active
Active
Operation Down to 2.7V
High-Z
High-Z
Active
Active
Active
Active
High-Z
Active
Active
Transmitter outputs will meet EIA/TIA-562 levels of
±3.7V with supply voltages as low as 2.7V.
SHDN
EN
T_OUT
0
0
0
1
1
1
0
1
Table 2. Required Minimum Capacitor Values
VCC
(V)
C1
(µF)
C2, C3, C4
(µF)
MAX3222/MAX3232/MAX3241
3.0 to 3.6
0.1
0.1
4.5 to 5.5
0.047
0.33
3.0 to 5.5
0.1
0.47
0.22
0.1
0.1
4.5 to 5.5
0.047
0.33
3.0 to 5.5
0.22
1.0
5V/div
Figure 3 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
2500pF. 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.
Mouse Driveability
0.22
3.15 to 3.6
Transmitter Outputs when
Exiting Shutdown
The MAX3241 has been specifically designed to power
serial mice while operating from low-voltage power supplies. It has been tested with leading mouse brands from
manufacturers such as Microsoft and Logitech. The
MAX3241 successfully drove all serial mice tested and
met their respective current and voltage requirements.
Figure 4a shows the transmitter output voltages under
increasing load current at 3.0V. Figure 4b shows a typical
mouse connection using the MAX3241.
MAX3237
3.0 to 3.6
Power-Supply Decoupling
In most circumstances, a 0.1µF bypass capacitor is
adequate. In applications that are sensitive to powersupply noise, decouple VCC to ground with a capacitor
of the same value as charge-pump capacitor C1. Connect
bypass capacitors as close to the IC as possible.
T2
2V/div
T1
50µs/div
VCC = 3.3V
C1–C4 = 0.1µF
Figure 3. Transmitter Outputs when Exiting Shutdown or
Powering Up
_______________________________________________________________________________________
9
MAX3222/MAX3232/MAX3237/MAX3241
Table 1. MAX3222/MAX3237/MAX3241
Shutdown and Enable Control Truth Table
6
5
4
3
VOUT+
VCC = 3.0V
2
1
T1
0
-1
T2
MAX3222-04
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3222/MAX3232/MAX3237/MAX3241
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
VOUT+
-2
-3
VCC
VOUT-
T3
VOUT-
-4
-5
-6
0
1
2
3
4
5
6
7
LOAD CURRENT PER TRANSMITTER (mA)
Figure 4a. MAX3241 Transmitter Output Voltage vs. Load Current per Transmitter
VCC = 3V
to 5.5V
28
C1
C2
24
C1+
0.1µF
26
VCC
V+
27
C3
C1-
1 C2+
2
C214 T1IN
COMPUTER SERIAL PORT
V-
MAX3241
3
C4
T1OUT 9
+V
13 T2IN
T2OUT 10
12 T3IN
T3OUT 11
+V
VCC
21
-V
R1OUTB
GND
20 R2OUTB
19 R1OUT
R1IN
4
5
18 R2OUT
5k
R2IN
17 R3OUT
5k
R3IN 6
16 R4OUT
5k
R4IN 7
Tx
MOUSE
5k
15 R5OUT
23
5k
EN
R5IN
8
SHDN 22
GND
25
Figure 4b. Mouse Driver Test Circuit
10
______________________________________________________________________________________
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
T1IN
5V/div
T1OUT
5V/div
R1OUT
5V/div
MAX3222/MAX3232/MAX3237/MAX3241
VCC
0.1µF
VCC
C1+
V+
C3
C1
C1-
MAX3222
MAX3232
MAX3237
MAX3241
C2+
C2
C2-
VC4
5µs/div
VCC = 3.3V
T_ OUT
T_ IN
Figure 6. MAX3241 Loopback Test Result at 120kbps
R_ IN
R_ OUT
0V
VCC
EN*
5k
SHDN*
1000pF
T1IN
5V/div
T1OUT
5V/div
R1OUT
5V/div
GND
* MAX3222/MAX3241 ONLY
Figure 5. Loopback Test Circuit
2µs/div
VCC = 3.3V
High Data Rates
The MAX3222/MAX3232/MAX3241 maintain the RS-232
±5.0V minimum transmitter output voltage even at high
data rates. Figure 5 shows a transmitter loopback test
circuit. Figure 6 shows a loopback test result at
120kbps, and Figure 7 shows the same test at 235kbps.
For Figure 6, all transmitters were driven simultaneously
at 120kbps into RS-232 loads in parallel with 1000pF.
For Figure 7, a single transmitter was driven at 235kbps,
and all transmitters were loaded with an RS-232 receiver
in parallel with 1000pF.
The MAX3237 maintains the RS-232 ±5.0V minimum
transmitter output voltage at data rates up to 1Mbps.
Figure 8 shows a loopback test result at 1Mbps with
MBAUD = V CC . For Figure 8, all transmitters were
loaded with an RS-232 receiver in parallel with 250pF.
Figure 7. MAX3241 Loopback Test Result at 235kbps
+5V
T_IN
0V
+5V
T_OUT = R_IN
5k + 250pF
0V
-5V
+5V
R_OUT
150pF
0V
200ns/div
VCC = 3.3V
Figure 8. MAX3237 Loopback Test Result at 1000kbps
(MBAUD = VCC)
______________________________________________________________________________________
11
MAX3222/MAX3232/MAX3237/MAX3241
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
Interconnection with 3V and 5V Logic
The MAX3222/MAX3232/MAX3237/MAX3241 can
directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 3 for more information on possible combinations of interconnections.
Table 3. Logic-Family Compatibility
with Various Supply Voltages
SYSTEM
POWERSUPPLY
VOLTAGE
(V)
MAX32_ _
VCC
SUPPLY
VOLTAGE
(V)
3.3
3.3
Compatible with all CMOS
families.
5
5
Compatible with all TTL
and CMOS-logic families.
5
3.3
Compatible with ACT and
HCT CMOS, and with TTL.
Incompatible with AC, HC,
and CD4000 CMOS.
COMPATIBILITY
__________________________________________________Typical Operating Circuits
+3.3V
+3.3V
17
0.1µF
C1
0.1µF
2 C1+
4
5
C2
0.1µF
6
V+
3
C3*
0.1µF
C1-
MAX3222
C2+
V-
0.1µF
T1OUT 15
10 R2OUT
C2+
MAX3232
R1IN 13
5k
9 R2OUT
R2IN 8
5k
SHDN
GND
15
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
C4
0.1µF
T2OUT 7
18
PIN NUMBERS REFER TO DIP/SO PACKAGES.
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
SEE TABLE 2 FOR CAPACITOR SELECTION
12
6
RS-232
OUTPUTS
5k
GND
16
V-
T1OUT 14
TTL/CMOS
OUTPUTS
R2IN 9
EN
C3*
0.1µF
C2-
12 R1OUT
RS-232
INPUTS
5k
2
C1-
10 T2IN
R1IN 14
TTL/CMOS
OUTPUTS
V+
TTL/CMOS
INPUTS
T2OUT 8
13 R1OUT
5
VCC
11 T1IN
RS-232
OUTPUTS
11 T2IN
3
4
C4
0.1µF
TTL/CMOS
INPUTS
1
1 C1+
0.1µF
7
C2-
12 T1IN
16
0.1µF
VCC
______________________________________________________________________________________
RS-232
INPUTS
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
0.1µF
+3.3V
26
28 C1+
0.1µF
VCC
27
25
1
0.1µF
3
C2+
24
MAX3237
V-
4
1
0.1µF
0.1µF
C2-
23 T2IN
22 T3IN
T1
T2
T3
VCC
27
V+
0.1µF
C1-
24 T1IN
LOGIC
INPUTS
28 C1+
V+
0.1µF
26
0.1µF
T1OUT 5
T2OUT 6
T3OUT 7
TTL/CMOS
INPUTS
RS-232
OUTPUTS
2
C2+
MAX3241
V-
3
C4
0.1µF
C2-
14 T1IN
T1OUT 9
13 T2IN
T2OUT 10
12 T3IN
T3OUT 11
RS-232
OUTPUTS
21 R1OUTB
19 T4IN
T4
T4OUT 10
20 R2OUTB
17 T5IN
T5
T5OUT 12
19 R1OUT
R1IN 4
16 R1OUTB
5k
R2IN
18 R2OUT
21 R1OUT
20 R2OUT
5
R1IN 8
R1
TTL/CMOS
OUTPUTS
5k
LOGIC
OUTPUTS
C3*
0.1µF
C1-
R2IN
R2
9
RS-232
INPUTS
5k
17 R3OUT
R3IN 6
RS-232
INPUTS
5k
5k
18 R3OUT
R3IN 11
R3
16 R4OUT
R4IN 7
5k
5k
15 R5OUT
MBAUD
13 EN
GND
SHDN
R5IN 8
15
14
2
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
5k
23 EN
GND
SHDN
22
25
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
______________________________________________________________________________________
13
MAX3222/MAX3232/MAX3237/MAX3241
_____________________________________Typical Operating Circuits (continued)
MAX3222/MAX3232/MAX3237/MAX3241
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
_____________________________________________Pin Configurations (continued)
TOP VIEW
EN 1
20 SHDN
C1+ 2
19 VCC
V+ 3
18 GND
17 T1OUT
C1- 4
C2+ 5
MAX3222
16 R1IN
15 R1OUT
C2- 6
V- 7
14 N.C.
T2OUT 8
13 T1IN
R2IN 9
12 T2IN
R2OUT 10
11 N.C.
C1+ 1
16 VCC
V+ 2
15 GND
C1- 3
14 T1OUT
MAX3232
C2+ 4
C2- 5
13 R1IN
12 R1OUT
V- 6
11 T1IN
T2OUT 7
10 T2IN
9 R2OUT
R2IN 8
DIP/SO/TSSOP
SSOP/TSSOP
C2+
1
28 C1+
C2+
1
28 C1+
GND
2
27 V+
C2-
2
27 V+
C2-
3
26 VCC
V-
3
26 VCC
V-
4
25 C1-
R1IN
4
25 GND
T1OUT
5
24 T1IN
5
6
R3IN
6
23 EN
7
22 T3IN
R4IN
7
22 SHDN
21 R1OUT
R5IN
8
21 R1OUTB
20 R2OUT
T1OUT
9
20 R2OUTB
MAX3241
T3OUT
R1IN
8
R2IN
9
19 T4IN
T2OUT 10
19 R1OUT
18 R3OUT
T3OUT 11
18 R2OUT
T3IN 12
17 R3OUT
T4OUT 10
R3IN 11
17 T5IN
T5OUT 12
EN 13
16 R1OUTB
T2IN 13
16 R4OUT
SHDN 14
15 MBAUD
T1IN 14
15 R5OUT
SSOP
14
24 C1-
R2IN
23 T2IN
MAX3237
T2OUT
SO/SSOP/TSSOP
______________________________________________________________________________________
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
PART
TEMP. RANGE
PIN-PACKAGE
PART
TEMP. RANGE
PIN-PACKAGE
MAX3222EUP
-40°C to +85°C
20 TSSOP
MAX3232EWE
-40°C to +85°C
16 Wide SO
MAX3222EAP
MAX3222EWN
MAX3222EPN
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
20 SSOP
18 SO
18 Plastic DIP
MAX3232EPE
-40°C to +85°C
16 Plastic DIP
MAX3237CAI
MAX3237EAI
MAX3241CUI
MAX3241CAI
0°C to +70°C
-40°C to +85°C
0°C to +70°C
0°C to +70°C
28 SSOP
28 SSOP
28 TSSOP
28 SSOP
MAX3222C/D
0°C to +70°C
Dice*
MAX3232CUE
MAX3232CSE
MAX3232CWE
0°C to +70°C
0°C to +70°C
0°C to +70°C
16 TSSOP
16 Narrow SO
16 Wide SO
MAX3232CPE
0°C to +70°C
16 Plastic DIP
MAX3232EUE
MAX3232ESE
-40°C to +85°C
-40°C to +85°C
16 TSSOP
16 Narrow SO
MAX3241CWI
0°C to +70°C
MAX3241EUI
MAX3241EAI
MAX3241EWI
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
28 SO
28 TSSOP
28 SSOP
28 SO
* Dice are tested at TA = +25°C, DC parameters only.
______3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim
PART
POWERSUPPLY
VOLTAGE
(V)
No. OF
TRANSMITTERS/
RECEIVERS
No. OF
RECEIVERS
ACTIVE IN
SHUTDOWN
GUARANTEED
DATA
RATE
(kbps)
EIA/
TIA-232
OR 562
MAX212
3.0 to 3.6
3/5
5
120
232
Drives mice
MAX218
1.8 to 4.25
2/2
2
120
232
Operates directly from batteries
without a voltage regulator
MAX562
MAX563
2.7 to 5.25
3.0 to 3.6
3/5
2/2
5
2
230
230
562
562
MAX3212
2.7 to 3.6
3/5
5
235
232
MAX3222
3.0 to 5.5
2/2
2
120
232
0.1µF capacitors
MAX3223
MAX3232
3.0 to 5.5
3.0 to 5.5
2/2
2/2
2
N/A
120
120
232
232
0.1µF capacitors, AutoShutdown
0.1µF capacitors
MAX3237
3.0 to 5.5
5/3
3
250/1000
232
0.1µF capacitors, 1 complementary receiver, MegaBaud
operation
MAX3241
3.0 to 5.5
3/5
5
120
232
0.1µF capacitors, 2 complementary receivers, drives mice
MAX3243
3.0 to 5.5
3/5
1
120
232
0.1µF capacitors, AutoShutdown,
complementary receiver,
drives mice
FEATURES
Wide supply range
0.1µF capacitors
AutoShutdown, complementary
receiver, drives mice, transient
detection
______________________________________________________________________________________
15
MAX3222/MAX3232/MAX3237/MAX3241
Ordering Information (continued)
___________________Chip Topography
___________________Chip Information
MAX3222
V+
C1+
EN
SHDN
V CC
GND
C1C2+
T1OUT
PART
TRANSISTOR COUNT
MAX3222
339
MAX3232
339
MAX3237
1212
MAX3241
894
0.127"
(3.225mm)
C2-
R1IN
VR1OUT
T2OUT R2IN R2OUT
T2IN T1IN
0.087"
(2.209mm)
TRANSISTOR COUNT: 339
SUBSTRATE CONNECTED TO GND
________________________________________________________Package Information
TSSOP.EPS
MAX3222/MAX3232/MAX3237/MAX3241
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232
Transceivers Using Four 0.1µF External Capacitors
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.
16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.