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19-0273; Rev 6; 10/03
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241*
________________General Description
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 0.1F 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 MegaBaudTM operating mode, while maintaining RS-232 output levels. The MAX3222/MAX3232 have 2 receivers and 2 drivers. The MAX3222 features a 1A 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 1A 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 1A 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.
__Next Generation Device Features
For Smaller Packaging: MAX3228E/MAX3229E: +2.5V to +5.5V RS-232 Transceivers in UCSPTM For Integrated ESD Protection: MAX3222E/MAX3232E/MAX3237E/MAX3241E*/ MAX3246E: 15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers For Low-Voltage or Data Cable Applications: MAX3380E/MAX3381E: +2.35V to +5.5V, 1A, 2 Tx/2 Rx RS-232 Transceivers with 15kV ESD-Protected I/O and Logic Pins
_______________Ordering Information
PART MAX3222CUP MAX3222CAP MAX3222CWN MAX3222CPN TEMP RANGE 0C to +70C 0C to +70C 0C to +70C 0C to +70C 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 C1+ 2 V+ 3 C1- 4 C2+ 5 C2VT2OUT R2IN 6 7 8 9 18 SHDN 17 VCC 16 GND 15 T1OUT
________________________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.
MAX3222
14 R1IN 13 R1OUT 12 T1IN 11 T2IN 10 R2OUT
DIP/SO Pin Configurations continued at end of data sheet.
MegaBaud and UCSP are trademarks of Maxim Integrated Products, Inc. *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 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.
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
ABSOLUTE MAXIMUM RATINGS
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 Continuous Power Dissipation (TA = +70C) 16-Pin TSSOP (derate 6.7mW/C above +70C).............533mW 16-Pin Narrow SO (derate 8.70mW/C above +70C) ....696mW 16-Pin Wide SO (derate 9.52mW/C above +70C)........762mW 16-Pin Plastic DIP (derate 10.53mW/C above +70C)...842mW 18-Pin SO (derate 9.52mW/C above +70C)..............762mW 18-Pin Plastic DIP (derate 11.11mW/C above +70C) ..889mW 20-Pin SSOP (derate 7.00mW/C above +70C) .........559mW 20-Pin TSSOP (derate 8.0mW/C above +70C).............640mW 28-Pin TSSOP (derate 8.7mW/C above +70C).............696mW 28-Pin SSOP (derate 9.52mW/C above +70C) .........762mW 28-Pin SO (derate 12.50mW/C above +70C) .....................1W Operating Temperature Ranges MAX32_ _C_ _.....................................................0C to +70C MAX32_ _E_ _ .................................................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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 = 0.1F (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER DC CHARACTERISTICS VCC Power-Supply Current Shutdown Supply Current Input Logic Threshold Low (Note 3) Input Logic Threshold High (Note 3) Input Leakage Current Output Leakage Current Output Voltage Low Output Voltage High RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High TA = +25C TA = +25C VCC = 5.0V VCC = 3.3V VCC = 5.0V VCC = 3.3V VCC = 5.0V -25 0.6 0.8 1.2 1.5 1.5 1.8 2.4 2.4 25 V V V No load, VCC = 3.3V or 5.0V, TA = +25C SHDN = GND, TA = +25C MAX3222/MAX3232/ MAX3241 MAX3237 0.3 0.5 1.0 1.0 2.0 10 A mA CONDITIONS MIN TYP MAX UNITS
LOGIC INPUTS AND RECEIVER OUTPUTS T_IN, EN, SHDN, MBAUD VCC = 3.3V VCC = 5.0V T_IN, EN, SHDN, MBAUD Receivers disabled IOUT = 1.6mA IOUT = -1.0mA VCC - 0.6 VCC - 0.1 2.0 2.4 0.01 0.05 1.0 10 0.4 0.8 V V A A V V
2
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3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +5.5V, C1-C4 = 0.1F (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Input Hysteresis Input Resistance TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current VOUT = 12V, VCC = 0V or 3V to 5.5V, transmitters disabled All transmitter outputs loaded with 3k to ground VCC = V+ = V- = 0V, TOUT = 2V 5.0 300 5.4 10M 35 60 25 V mA A TA = +25C 3 CONDITIONS MIN TYP 0.3 5 7 MAX UNITS V k
MAX3222/MAX3232/MAX3237/MAX3241
MOUSE DRIVEABILITY (MAX3241) Transmitter Output Voltage T1IN = T2IN = GND, T3IN = VCC, T3OUT loaded with 3k 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 = 0.1F (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Maximum Data Rate Receiver Propagation Delay Receiver Output Enable Time Transmitter Skew Receiver Skew CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching R_IN to R_OUT, CL = 150pF Normal operation tPHL tPLH MIN 120 TYP 235 0.3 0.3 200 200 300 300 CL = 150pF to 1000pF CL = 150pF to 2500pF 6 4 30 V/s 30 MAX UNITS kbps s ns ns ns ns
Receiver Output Disable Time Normal operation
| tPHL - tPLH | | tPHL - tPLH |
VCC = 3.3V, RL = 3k to 7k, +3V to -3V or -3V to +3V, TA = +25C, one transmitter switching
Transition-Region Slew Rate
_______________________________________________________________________________________
3
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
TIMING CHARACTERISTICS--MAX3237
(VCC = +3.0V to +5.5V, C1-C4 = 0.1F (Note 2), TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching, MBAUD = GND Maximum Data Rate VCC = 3.0V to 4.5V, RL = 3k, CL = 250pF, one transmitter switching, MBAUD = VCC VCC = 4.5V to 5.5V, RL = 3k, CL = 1000pF, one transmitter switching, MBAUD = VCC Receiver Propagation Delay Receiver Output Enable Time R_IN to R_OUT, CL = 150pF Normal operation tPHL tPLH MIN 250 1000 1000 0.15 0.15 200 200 100 25 50 CL = 150pF to 1000pF MBAUD = GND MBAUD = VCC 6 24 4 30 150 30 V/s s ns ns ns ns ns kbps TYP MAX UNITS
Receiver Output Disable Time Normal operation Transmitter Skew Receiver Skew
| tPHL - tPLH |, MBAUD = GND | tPHL - tPLH |, MBAUD = VCC | tPHL - tPLH |
Transition-Region Slew Rate
VCC = 3.3V, RL = 3 to 7k, +3V to -3V or -3V to +3V, TA = +25C
CL = 150pF to 2500pF, MBAUD = GND
Note 2: MAX3222/MAX3232/MAX3241: C1-C4 = 0.1F tested at 3.3V 10%; C1 = 0.047F, C2-C4 = 0.33F tested at 5.0V 10%. MAX3237: C1-C4 = 0.1F tested at 3.3V 5%; C1-C4 = 0.22F tested at 3.3V 10%; C1 = 0.047F, C2-C4 = 0.33F tested at 5.0V 10%. Note 3: Transmitter input hysteresis is typically 250mV.
__________________________________________Typical Operating Characteristics
(VCC = +3.3V, 235kbps data rate, 0.1F capacitors, all transmitters loaded with 3k, TA = +25C, unless otherwise noted.)
MAX3222/MAX3232 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3222-01
MAX3222/MAX3232 SLEW RATE vs. LOAD CAPACITANCE
20 18 SLEW RATE (V/s) 16 14 12 10 8 6 4 2 0 5000 150 1000 2000 3000 4000 5000 5 0 +SLEW -SLEW FOR DATA RATES UP TO 235kbps
MAX3222-02
MAX3222/MAX3232 SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA
35 235kbps SUPPLY CURRENT (mA) 30 25 120kbps 20 15 20kbps 10
MAX3222-03
TRANSMITTER OUTPUT VOLTAGE (V)
6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0 1000 2000 3000
22
40
VOUT+
VOUT-
4000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
4
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3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.3V, 235kbps data rate, 0.1F capacitors, all transmitters loaded with 3k, TA = +25C, unless otherwise noted.)
MAX3241 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3222-04
MAX3222/MAX3232/MAX3237/MAX3241
MAX3241 SLEW RATE vs. LOAD CAPACITANCE
MAX3222-05
MAX3241 SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA
40 SUPPLY CURRENT (mA) 35 30 25 20 15 10 5 0 5000 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) 20kbps 120kbps 235kbps
MAX3222-06
7.5 TRANSMITTER OUTPUT VOLTAGE (V) VOUT+ 5.0 2.5 0 -2.5 -5.0 -7.5 0 1000 2000 3000 4000 VOUT-
24 22 20 SLEW RATE (V/s) 18 16 14 12 10 8 6 4 +SLEW ALL OUTPUTS LOADED WITH 3k +CL 0.1F CHARGE-PUMP CAPACITORS FOR ALL DATA RATES UP TO 235kbps 0 1000 2000 3000 4000
45
1 TRANSMITTER AT 235kbps 2 TRANSMITTERS AT 30kbps
-SLEW
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3237 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (MBAUD = GND)
MAX3222-07
MAX3237 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (MBAUD = VCC)
TRANSMITTER OUTPUT VOLTAGE (V) 1Mbps 5.0 2.5 0 -2.5 -5.0 -7.5 2Mbps 1.5Mbps 2 1Mbps 0 0 500 1000 1500 2000 0 LOAD CAPACITANCE (pF) 1 TRANSMITTER AT FULL DATA RATE 4 TRANSMITTERS AT 1/16 DATA RATE 3k + CL LOAD, EACH OUTPUT VCC = 3.3V 2Mbps 1.5Mbps
MAX3222-08
MAX3237 SLEW RATE vs. LOAD CAPACITANCE (MBAUD = GND)
MAX3222-09
7.5 TRANSMITTER OUTPUT VOLTAGE (V) 5.0 2.5 0 -2.5 -5.0 -7.5 0 1000 2000 3000 4000
7.5
12 10 SLEW RATE (V/s) +SLEW 8 6 4 1 TRANSMITTER AT 240kbps 4 TRANSMITTERS AT 15kbps 3k + CL LOADS VCC = 3.3V 1000 2000 3000 4000 -SLEW
1 TRANSMITTER AT 240kbps 4 TRANSMITTERS AT 15kbps 3k + CL LOADS VCC = 3.3V
5000
5000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
MAX3237 SLEW RATE vs. LOAD CAPACITANCE (MBAUD = VCC)
MAX3222-10
MAX3237 SUPPLY CURRENT vs. LOAD CAPACITANCE (MBAUD = GND)
MAX3222-11
MAX3237 SKEW vs. LOAD CAPACITANCE (tPLH - tPHL)
60 50 40 1 TRANSMITTER AT 512kbps 4 TRANSMITTERS AT 32kbps 3k + CL LOADS VCC = 3.3V MBAUD = VCC MAX AVERAGE; 10 PARTS SKEW (ns)
MAX3222-12
70 60 SLEW RATE (V/s) 50 40 30 20 10 0 0 -SLEW, 1Mbps +SLEW, 1Mbps -SLEW, 2Mbps +SLEW, 2Mbps
60 50 SUPPLY CURRENT (mA) 40 30 20kbps 20 10 0 1 TRANSMITTER AT FULL DATA RATE 4 TRANSMITTERS AT 1/16 DATA RATE 3k + CL LOADS VCC = 3.3V 0 1000 2000 3000 4000 240kbps 120kbps
70
30 20 10 0 0
1 TRANSMITTER AT FULL DATA RATE 4 TRANSMITTERS AT 1/16 DATA RATE 3k + CL LOAD EACH OUTPUT VCC = 3.3V 500 1000 1500 2000
MIN
5000
500
1000
1500
2000
2500
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
_______________________________________________________________________________________
5
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
______________________________________________________________Pin Description
PIN MAX3222 MAX3232 DIP/SO 1 2 3 4 5 6 7 8, 15 9, 14 10, 13 11, 12 16 17 18 -- -- -- SSOP 1 2 3 4 5 6 7 8, 17 9, 16 10, 15 12, 13 18 19 20 11, 14 -- -- -- 1 2 3 4 5 6 7, 14 8, 13 9, 12 10, 11 15 16 -- -- -- -- 13 28 27 25 1 3 4 5, 6, 7, 10, 12 8, 9, 11 18, 20, 21 17, 19, 22, 23, 24 2 26 14 -- 15 16 23 28 27 24 1 2 3 9, 10, 11 4-8 15-19 12, 13, 14 25 26 22 -- -- 20, 21 EN C1+ V+ C1C2+ C2VT_OUT R_IN R_OUT T_IN GND VCC SHDN N.C. MBAUD R_OUTB Receiver Enable. Active low. Positive Terminal of Voltage-Doubler Charge-Pump Capacitor +5.5V Generated by the Charge Pump Negative Terminal of Voltage-Doubler Charge-Pump Capacitor Positive Terminal of Inverting Charge-Pump Capacitor Negative Terminal of Inverting Charge-Pump Capacitor -5.5V Generated by the Charge Pump RS-232 Transmitter Outputs RS-232 Receiver Inputs TTL/CMOS Receiver Outputs TTL/CMOS Transmitter Inputs Ground +3.0V to +5.5V Supply Voltage Shutdown Control. Active low. No Connection MegaBaud Control Input. Connect to GND for normal operation; connect to VCC for 1Mbps transmission rates. Noninverting Complementary Receiver Outputs. Always active. MAX3237 MAX3241 NAME FUNCTION
6
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3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
_______________Detailed Description
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. 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 pullup resistors. Connect unused inputs to GND or VCC.
MAX3222/MAX3232/MAX3237/MAX3241
MAX3237 MegaBaud Operation
In normal operating mode (MBAUD = GND), the MAX3237 transmitters guarantee a 250kbps data rate with worst-case loads of 3k in parallel with 1000pF. This provides compatibility with PC-to-PC communication software, such as LaplinkTM. 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 3k 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 3k in parallel with 1000pF.
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 3k in parallel with 1000pF, providing compatibility with PC-toPC communication software (such as LapLinkTM). Typically, these three devices can operate at data rates of 235kbps. Transmitters can be paralleled to drive multiple receivers or mice.
LapLink is a trademark of Traveling Software.
VCC 0.1F VCC
VCC 0.1F VCC
C1+ C1 C1C2+ C2 C2T_ IN
V+ C3 C1
C1+ C1-
V+ C3
MAX3222 MAX3232 MAX3237 MAX3241
VC4 T_ OUT C2
C2+ C2T_ IN
MAX3222 MAX3232 MAX3237 MAX3241
VC4 T_ OUT
R_ OUT 0V VCC EN* 5k SHDN* GND
R_ IN 0V VCC
R_ OUT EN* 5k SHDN* GND
R_ IN
3k
2500pF
7k
150pF
* MAX3222/MAX3241 ONLY
MINIMUM SLEW-RATE TEST CIRCUIT Figure 1. Slew-Rate Test Circuits _______________________________________________________________________________________ 7 MAXIMUM SLEW-RATE TEST CIRCUIT
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
RS-232 Receivers
VCC
VCC Rx PROTECTION DIODE UART Tx GND SHDN = GND
PREVIOUS RS-232
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).
5k
MAX3222/MAX3237/MAX3241 Shutdown Mode
Supply current falls to less than 1A 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 100s, 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.
a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE RECEIVER OUTPUT IN SHUTDOWN.
VCC TO P LOGIC TRANSITION DETECTOR
MAX3222/MAX3237/MAX3241 Enable Control
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.
MAX3237 MAX3241
R1OUTB VCC Rx PROTECTION DIODE UART Tx GND T1IN SHDN = GND R1OUT EN = VCC 5k T1OUT R1IN
__________Applications Information
Capacitor Selection
The capacitor type used for C1-C4 is not critical for proper operation; polarized or nonpolarized capacitors can be used. The charge pump requires 0.1F 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-.
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
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3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
Table 1. MAX3222/MAX3237/MAX3241 Shutdown and Enable Control Truth Table
SHDN 0 0 1 1 EN 0 1 0 1 T_OUT High-Z High-Z Active Active R_OUT Active High-Z Active High-Z R_OUTB (MAX3237/ MAX3241) Active Active Active Active
Power-Supply Decoupling
In most circumstances, a 0.1F 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.
MAX3222/MAX3232/MAX3237/MAX3241
Operation Down to 2.7V
Transmitter outputs will meet EIA/TIA-562 levels of 3.7V with supply voltages as low as 2.7V.
Transmitter Outputs when Exiting Shutdown
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 3k 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.
Table 2. Required Minimum Capacitor Values
VCC (V) C1 (F) C2, C3, C4 (F)
MAX3222/MAX3232/MAX3241 3.0 to 3.6 4.5 to 5.5 3.0 to 5.5 MAX3237 3.0 to 3.6 3.15 to 3.6 4.5 to 5.5 3.0 to 5.5 0.22 0.1 0.047 0.22 0.22 0.1 0.33 1.0 0.1 0.047 0.1 0.1 0.33 0.47
Mouse Driveability
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.
5V/div
T2
2V/div
T1
50s/div VCC = 3.3V C1-C4 = 0.1F
Figure 3. Transmitter Outputs when Exiting Shutdown or Powering Up _______________________________________________________________________________________ 9
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
TRANSMITTER OUTPUT VOLTAGE (V)
4 3 2 1 0 -1 -2 -3 -4 -5 -6 0
VCC = 3.0V
T1
VOUT+
VOUT+
T2
VCC
T3
VOUTVOUT-
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
0.1F 26 VCC 27 C3 COMPUTER SERIAL PORT 3 C4
28 C1 24
C1+ C1-
V+
C2
1 C2+ 2 C214 T1IN 13 T2IN
MAX3241
V-
T1OUT 9 +V T2OUT 10 +V T3OUT 11 -V GND R1IN 4 5k 5k 5k 5k 5k SHDN GND 25 R2IN 5 R3IN 6 R4IN 7 MOUSE R5IN 8 22 Tx
VCC
12 T3IN 21 R1OUTB
20 R2OUTB 19 R1OUT 18 R2OUT 17 R3OUT 16 R4OUT 15 R5OUT 23 EN
Figure 4b. Mouse Driver Test Circuit 10 ______________________________________________________________________________________
MAX3222-04
6 5
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
VCC 0.1F
T1IN
5V/div
VCC C1+ C1 C1C2+ C2 C2V+ C3
T1OUT
5V/div
R1OUT
5V/div
MAX3222 MAX3232 MAX3237 MAX3241
VC4 5s/div VCC = 3.3V T_ OUT
T_ IN
Figure 6. MAX3241 Loopback Test Result at 120kbps
R_ OUT 0V VCC EN* R_ IN 5k
1000pF T1IN 5V/div
SHDN*
GND T1OUT 5V/div
* MAX3222/MAX3241 ONLY
R1OUT
5V/div
Figure 5. Loopback Test Circuit
VCC = 3.3V
2s/div
Figure 7. MAX3241 Loopback Test Result at 235kbps
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.
+5V 0V +5V 0V -5V +5V 0V R_OUT 150pF 200ns/div
VCC = 3.3V
T_IN
T_OUT = R_IN 5k + 250pF
Figure 8. MAX3237 Loopback Test Result at 1000kbps (MBAUD = VCC) ______________________________________________________________________________________ 11
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
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) 3.3 5 MAX32_ _ VCC SUPPLY VOLTAGE (V) 3.3 5
COMPATIBILITY
Compatible with all CMOS families. Compatible with all TTL and CMOS-logic families. Compatible with ACT and HCT CMOS, and with TTL. Incompatible with AC, HC, and CD4000 CMOS.
5
3.3
__________________________________________________Typical Operating Circuits
+3.3V 0.1F C1 0.1F 2 C1+ 4 5 C2 0.1F 6 C117 VCC V+ 3 C3* 0.1F 0.1F +3.3V 0.1F 1 C1+ 3 4 C4 0.1F 0.1F 5 C1C2+ C2T1OUT 14 RS-232 OUTPUTS 10 T2IN T2OUT 7 16 VCC V+ 2 C3* 0.1F 6 C4 0.1F
MAX3222
C2+ C2V-
7
MAX3232
V-
12 T1IN TTL/CMOS INPUTS 11 T2IN
T1OUT 15 RS-232 OUTPUTS T2OUT 8 TTL/CMOS INPUTS
11 T1IN
13 R1OUT TTL/CMOS OUTPUTS 10 R2OUT 1 EN GND 16
R1IN 14 5k R2IN 9 5k SHDN 18 RS-232 INPUTS TTL/CMOS OUTPUTS
12 R1OUT
R1IN 13 5k RS-232 INPUTS
9 R2OUT
R2IN 8 5k
GND 15
PIN NUMBERS REFER TO DIP/SO PACKAGES.
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
SEE TABLE 2 FOR CAPACITOR SELECTION
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
12
______________________________________________________________________________________
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
_____________________________________Typical Operating Circuits (continued)
MAX3222/MAX3232/MAX3237/MAX3241
0.1F +3.3V 26 28 C1+ 0.1F 25 C11 0.1F 3 C2+ C2T1 T2 T1OUT 5 T2OUT 6 T3OUT 7 RS-232 OUTPUTS VCC V+ 27 0.1F 24 C1C2+ C2T1OUT 9 T2OUT 10 T3OUT 11 4 0.1F 0.1F 1 2 0.1F 0.1F 28 C1+ 26 VCC V+ C3* 0.1F 27
MAX3237
V-
MAX3241
V-
3 C4 0.1F
24 T1IN 23 T2IN LOGIC INPUTS 22 T3IN 19 T4IN 17 T5IN 16 R1OUTB
14 T1IN 13 T2IN 12 T3IN 21 R1OUTB 20 R2OUTB
TTL/CMOS INPUTS
RS-232 OUTPUTS
T3 T4 T5
T4OUT 10 T5OUT 12 19 R1OUT 5k 18 R2OUT R2IN 5k 17 R3OUT 5k 16 R4OUT R4IN 7 5k 15 R5OUT MBAUD 15 14 23 EN GND 25 SHDN 5k 22 R5IN 8 R3IN 6 RS-232 INPUTS 5 R1IN 4
21 R1OUT
R1 5k
R1IN 8 TTL/CMOS OUTPUTS R2IN 5k 9 RS-232 INPUTS
LOGIC UTPUTS
20 R2OUT
R2
18 R3OUT
R3 5k
R3IN 11
13 EN GND 2
SHDN
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
* C3 CAN BE RETURNED TO EITHER VCC OR GROUND.
______________________________________________________________________________________
13
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
_____________________________________________Pin Configurations (continued)
TOP VIEW
EN 1 C1+ 2 V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 T2OUT 8 R2IN 9 R2OUT 10 20 SHDN 19 VCC 18 GND 17 T1OUT C1+ 1 V+ 2 C1- 3 C2+ 4 C2- 5 V- 6 T2OUT 7 R2IN 8
16 VCC 15 GND 14 T1OUT
MAX3222
16 R1IN 15 R1OUT 14 N.C. 13 T1IN 12 T2IN 11 N.C.
MAX3232
13 R1IN 12 R1OUT 11 T1IN 10 T2IN 9 R2OUT
DIP/SO/TSSOP SSOP/TSSOP
C2+ GND C2VT1OUT T2OUT T3OUT R1IN R2IN
1 2 3 4 5 6 7 8 9
28 C1+ 27 V+ 26 VCC 25 C124 T1IN
C2+ C2VR1IN R2IN R3IN R4IN R5IN T1OUT
1 2 3 4 5 6 7 8 9
28 C1+ 27 V+ 26 VCC 25 GND 24 C1-
MAX3237
23 T2IN 22 T3IN 21 R1OUT 20 R2OUT 19 T4IN 18 R3OUT 17 T5IN 16 R1OUTB 15 MBAUD
MAX3241
23 EN 22 SHDN 21 R1OUTB 20 R2OUTB 19 R1OUT 18 R2OUT 17 R3OUT 16 R4OUT 15 R5OUT
T4OUT 10 R3IN 11 T5OUT 12 EN 13 SHDN 14
T2OUT 10 T3OUT 11 T3IN 12 T2IN 13 T1IN 14
SSOP
SO/SSOP/TSSOP
14
______________________________________________________________________________________
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
Ordering Information (continued)
PART MAX3222EUP MAX3222EAP MAX3222EWN MAX3222EPN MAX3222C/D MAX3232CUE MAX3232CSE MAX3232CWE MAX3232CPE MAX3232EUE MAX3232ESE TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C 0C to +70C 0C to +70C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 20 TSSOP 20 SSOP 18 SO 18 Plastic DIP Dice* 16 TSSOP 16 Narrow SO 16 Wide SO 16 Plastic DIP 16 TSSOP 16 Narrow SO PART MAX3232EWE MAX3232EPE MAX3237CAI MAX3237EAI MAX3241CUI MAX3241CAI MAX3241CWI MAX3241EUI MAX3241EAI MAX3241EWI TEMP RANGE -40C to +85C -40C to +85C 0C to +70C -40C to +85C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 16 Wide SO 16 Plastic DIP 28 SSOP 28 SSOP 28 TSSOP 28 SSOP 28 SO 28 TSSOP 28 SSOP 28 SO
MAX3222/MAX3232/MAX3237/MAX3241
* Dice are tested at TA = +25C, DC parameters only.
______3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim
POWERSUPPLY VOLTAGE (V) 3.0 to 3.6 1.8 to 4.25 2.7 to 5.25 3.0 to 3.6 2.7 to 3.6 3.0 to 5.5 3.0 to 5.5 3.0 to 5.5 3.0 to 5.5 No. OF TRANSMITTERS/ RECEIVERS 3/5 2/2 3/5 2/2 3/5 2/2 2/2 2/2 5/3 No. OF RECEIVERS ACTIVE IN SHUTDOWN 5 2 5 2 5 2 2 N/A 3 GUARANTEED DATA RATE (kbps) 120 120 230 230 235 120 120 120 250/1000 EIA/ TIA-232 OR 562 232 232 562 562 232 232 232 232 232
PART
FEATURES
MAX212 MAX218 MAX562 MAX563 MAX3212 MAX3222 MAX3223 MAX3232 MAX3237
Drives mice Operates directly from batteries without a voltage regulator Wide supply range 0.1F capacitors AutoShutdown, complementary receiver, drives mice, transient detection 0.1F capacitors 0.1F capacitors, AutoShutdown 0.1F capacitors 0.1F capacitors, 1 complementary receiver, MegaBaud operation 0.1F capacitors, 2 complementary receivers, drives mice 0.1F capacitors, AutoShutdown, complementary receiver, drives mice
MAX3241
3.0 to 5.5
3/5
5
120
232
MAX3243
3.0 to 5.5
3/5
1
120
232
______________________________________________________________________________________
15
3.0V to 5.5V, Low-Power, up to 1Mbps, True RS-232 Transceivers Using Four 0.1F External Capacitors
MAX3222/MAX3232/MAX3237/MAX3241
___________________Chip Topography
MAX3222
V+ C1+ EN SHDN V CC
___________________Chip Information
PART MAX3222 TRANSISTOR COUNT 339 339 1212 894
GND
MAX3232 MAX3237
C1C2+ T1OUT 0.127" (3.225mm) C2R1IN
MAX3241
VR1OUT
T2OUT R2IN R2OUT 0.087" (2.209mm)
T2IN T1IN
TRANSISTOR COUNT: 339 SUBSTRATE CONNECTED TO GND
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
TSSOP4.40mm.EPS
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 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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