19-1283; Rev 2; 1/98 ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown The MAX3221E/MAX3223E/MAX3243E are 3V-powered EIA/TIA-232 and V.28/V.24 communications interfaces with automatic shutdown/wakeup features, high datarate capabilities, and enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to ±15kV using IEC 1000-4-2 AirGap Discharge, to ±8kV using IEC 1000-4-2 Contact Discharge, and to ±15kV using the Human Body Model. The MAX3221E/MAX3223E/MAX3243E achieve a 1µA supply current with Maxim’s revolutionary AutoShutdown™ feature. They save power without changes to the existing BIOS or operating system by entering low-power shutdown mode when the RS-232 cable is disconnected, or when the transmitters of the connected peripherals are off. The transceivers have a proprietary low-dropout transmitter output stage, delivering true RS-232 performance from a +3.0V to +5.5V supply with a dual charge pump. The charge pump requires only four small 0.1µF capacitors for operation from a +3.3V supply. Each device is guaranteed to run at data rates of 250kbps while maintaining RS-232 output levels. The MAX3221E contains just one driver and one receiver, making it the smallest single-supply RS-232 transceiver. The MAX3223E has two drivers and two receivers. The MAX3243E is a complete 3-driver/5-receiver serial port ideal for notebook or subnotebook computers. It also includes two noninverting receiver outputs that are always active, allowing external devices to be monitored without forward biasing the protection diodes in circuitry that may be powered down. The MAX3221E, MAX3223E, and MAX3243E are available in space-saving SSOP packages. Features ♦ ESD Protection for RS-232 I/O Pins: ±15kV—Human Body Model ±8kV—IEC1000-4-2, Contact Discharge ±15kV—IEC1000-4-2, Air-Gap Discharge ♦ Latchup Free ♦ 1µA Supply Current ♦ 250kbps Guaranteed Data Rate ♦ 6V/µs Guaranteed Slew Rate ♦ Meets EIA/TIA-232 Specifications Down to 3.0V ♦ Smallest Single-Supply RS-232 Transceiver (MAX3221E) ♦ Guaranteed Mouse Driveability (MAX3243E) ♦ Small 0.1µF Capacitors Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX3221ECAE 0°C to +70°C 16 SSOP MAX3221EEAE -40°C to +85°C 16 SSOP MAX3223ECPP 0°C to +70°C 20 Plastic DIP MAX3223ECAP 0°C to +70°C 20 SSOP MAX3223EEPP -40°C to +85°C 20 Plastic DIP MAX3223EEAP -40°C to +85°C 20 SSOP MAX3243ECWI 0°C to +70°C 28 Wide SO MAX3243ECAI 0°C to +70°C 28 SSOP MAX3243EEWI -40°C to +85°C 28 Wide SO MAX3243EEAI -40°C to +85°C 28 SSOP Applications Selector Guide Notebook, Subnotebook, and Palmtop Computers Cellular Phones Battery-Powered Equipment Hand-Held Equipment Peripherals Printers PART NO. OF VCC RANGE DRIVERS/ (V) RECEIVERS AUTOSHUTDOWN MAX3221E 1/1 3.0 to 5.5 ✔ MAX3223E 2/2 3.0 to 5.5 ✔ MAX3243E 3/5 3.0 to 5.5 ✔ Pin Configurations appear at end of data sheet. Typical Operating Circuits appear at end of data sheet. AutoShutdown 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; 5,649,210; 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 408-737-7600 ext. 3468. MAX3221E/MAX3223E/MAX3243E † General Description MAX3221E/MAX3223E/MAX3243E ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown ABSOLUTE MAXIMUM RATINGS VCC to GND ..............................................................-0.3V to +6V V+ to GND (Note 1) ..................................................-0.3V to +7V V- to GND (Note 1) ...................................................+0.3V to -7V V+ + |V-| (Note 1) .................................................................+13V Input Voltages T_IN, EN, FORCEON, FORCEOFF to GND ............-0.3V to +6V R_IN to GND ......................................................................±25V Output Voltages T_OUT to GND................................................................±13.2V R_OUT, R2OUTB, INVALID to GND .........-0.3V to (VCC + 0.3V) Short-Circuit Duration T_OUT to GND .........................................................Continuous Continuous Power Dissipation (TA = +70°C) 16-Pin SSOP (derate 7.14mW/°C above +70°C) ...........571mW 20-Pin Plastic DIP (derate 11.11mW/°C above +70°C)....889mW 20-Pin SSOP (derate 8.00mW/°C above +70°C) ...........640mW 28-Pin Wide SO (derate 12.50mW/°C above +70°C)............1W 28-Pin SSOP (derate 9.52mW/°C above +70°C)............762mW Operating Temperature Ranges MAX32_ _EC_ _ ....................................................0°C to +70°C MAX32_ _EE_ _..................................................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 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 SYMBOL CONDITIONS MIN TYP MAX UNITS DC CHARACTERISTICS (VCC = 3.3V or 5.0V, TA = +25°C) Supply Current, AutoShutdown FORCEON = GND, FORCEOFF = VCC, all R_IN open 1.0 10 µA Supply Current, Shutdown FORCEOFF = GND 1.0 10 µA Supply Current, AutoShutdown Disabled FORCEON = FORCEOFF = VCC, no load 0.3 1 mA 0.8 V LOGIC INPUTS Input Logic Threshold Low T_IN, EN, FORCEON, FORCEOFF Input Logic Threshold High T_IN, EN, FORCEON, FORCEOFF VCC = 3.3V 2.0 VCC = 5.0V 2.4 Transmitter Input Hysteresis V 0.5 V T_IN, EN, FORCEON, FORCEOFF ±0.01 ±1 µA Output Leakage Current R_OUT receivers disabled ±0.05 ±10 µA Output Voltage Low IOUT = 1.6mA 0.4 V Output Voltage High IOUT = -1.0mA Input Leakage Current RECEIVER OUTPUTS VCC - 0.6 VCC - 0.1 V AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC) 2 Receiver Input Threshold to INVALID Output High Figure 5a Receiver Input Threshold to INVALID Output Low Figure 5a INVALID Output Voltage Low IOUT = 1.6mA INVALID Output Voltage High IOUT = -1.0mA Positive threshold Negative threshold 2.7 -2.7 -0.3 VCC - 0.6 _______________________________________________________________________________________ V 0.3 V 0.4 V V ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown (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 SYMBOL CONDITIONS MIN TYP MAX UNITS Receiver Positive or Negative Threshold to INVALID High tINVH VCC = 5V, Figure 5b 1 µs Receiver Positive or Negative Threshold to INVALID Low tINVL VCC = 5V, Figure 5b 30 µs Receiver or Transmitter Edge to Transmitters Enabled tWU VCC = 5V, Figure 5b 100 µs RECEIVER INPUTS Input Voltage Range -25 25 V Input Voltage Range -25 25 V Input Threshold Low TA = +25°C Input Threshold High TA = +25°C 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 Input Hysteresis 0.5 Input Resistance 3 5 V V 7 kΩ TRANSMITTER OUTPUTS Output Voltage Swing All transmitter outputs loaded with 3kΩ to ground ±5 ±5.4 Output Resistance VCC = V+ = V- = 0, TOUT = ±2V 300 10M Output Short-Circuit Current Output Leakage Current VOUT = ±12V, VCC = 0 or 3V to 5.5V, transmitters disabled V Ω ±60 mA ±25 µA MOUSE DRIVEABILITY (MAX3243E) 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 ESD PROTECTION R_IN, T_OUT IEC 1000-4-2 Air-Gap Discharge ±15 IEC 1000-4-2 Contact Discharge ±8 Human Body Model ±15 kV kV _______________________________________________________________________________________ 3 MAX3221E/MAX3223E/MAX3243E ELECTRICAL CHARACTERISTICS (continued) TIMING CHARACTERISTICS—MAX3221E/MAX3223E/MAX3243E (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 SYMBOL Maximum Data Rate tPHL Receiver Propagation Delay CONDITIONS MIN RL = 3kΩ, CL = 1000pF, one transmitter switching 250 TYP UNITS kbps 0.15 CL = 150pF tPLH MAX µs 0.15 Receiver Output Enable Time Normal operation 200 ns Receiver Output Disable Time Normal operation 200 ns (Note 3) 100 ns 50 ns Transmitter Skew tPHL - tPLH Receiver Skew tPHL - tPLH VCC = 3.3V, RL = 3kΩ to 7kΩ, TA = +25°C, measured from +3V to -3V or -3V to +3V Transition-Region Slew Rate CL = 150pF to 1000pF 6 30 V/µs CL = 150pF to 2500pF 4 30 Note 2: C1–C4 = 0.1µF, tested at 3.3V ±10%. C1 = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%. Note 3: Transmitter skew is measured at the transmitter zero cross points. Typical Operating Characteristics (VCC = +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ and CL, TA = +25°C, unless otherwise noted.) MAX3221E/MAX3223E TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE VOUT+ 4 3 2 14 1 0 -1 -2 -3 -4 -5 -6 SLEW RATE (V/µs) 12 T1 TRANSMITTING AT 250kbps T2 (MAX3223E) TRANSMITTING AT 15.6kbps -SLEW 10 +SLEW 8 6 4 2 VOUT- FOR DATA RATES UP TO 250kbps 0 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 4 16 MAX3221-TOC2 6 5 MAX3221E/MAX3223E SLEW RATE vs. LOAD CAPACITANCE MAX3221E-01 TRANSMITTER OUTPUT VOLTAGE (V) MAX3221E/MAX3223E/MAX3243E ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown 5000 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 5000 ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown 250kbps 35 30 120kbps 25 20 20kbps 15 10 T1 TRANSMITTING AT 250kbps T2 (MAX3223E) TRANSMITTING AT 15.6kbps 5 6 5 1 TRANSMITTER AT 250kbps 2 TRANSMITTERS AT 15.6kbps 2 1 0 -1 -2 -3 -4 VOUT- -5 -6 0 0 1000 2000 3000 4000 0 5000 1000 2000 3000 4000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) MAX3243E SLEW RATE vs. LOAD CAPACITANCE MAX3243E OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE 50 SUPPLY CURRENT (mA) 12 10 8 6 4 250kbps 40 120kbps 30 20kbps 20 10 2 0 5000 60 MAX3243E-05 14 SLEW RATE (V/µs) VOUT+ 4 3 MAX3243E-06 SUPPLY CURRENT (mA) 40 TRANSMITTER OUTPUT VOLTAGE (V) MAX3224E-03 45 MAX3224E-04 MAX3243E TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE MAX3221E/MAX3223E OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE T1 TRANSMITTING AT 250kbps T2 (MAX3223E) TRANSMITTING AT 15.6kbps 0 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 5000 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 5 MAX3221E/MAX3223E/MAX3243E Typical Operating Characteristics (continued) (VCC = +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ and CL, TA = +25°C, unless otherwise noted.) ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown MAX3221E/MAX3223E/MAX3243E Pin Description PIN NAME FUNCTION — EN Receiver Enable Control. Drive low for normal operation. Drive high to force the receiver outputs (R_OUT) into a high-impedance state. 2 28 C1+ 3 3 27 V+ +5.5V generated by the charge pump 4 4 24 C1- Negative terminal of the voltage doubler Charge-Pump Capacitor 5 5 1 C2+ Positive terminal of inverting Charge-Pump Capacitor 6 6 2 C2- Negative terminal of inverting Charge-Pump Capacitor 7 7 3 V- 8 9, 16 4–8 R_IN 9 10, 15 15–19 R_OUT 10 11 21 INVALID 11 12, 13 12, 13, 14 T_IN 12 14 23 FORCEON 13 8, 17 9, 10, 11 T_OUT — — 20 R2OUTB 14 18 25 GND Ground 15 19 26 VCC +3.0V to +5.5V Supply Voltage 16 20 22 FORCEOFF MAX3221E MAX3223E MAX3243E 1 1 2 Positive terminal of the voltage doubler Charge-Pump Capacitor -5.5V generated by the charge pump RS-232 Receiver Inputs TTL/CMOS Receiver Outputs Output of the Valid Signal Detector. INVALID is enabled high if a valid RS-232 level is present on any receiver input. TTL/CMOS Transmitter Inputs Drive high to override automatic circuitry keeping transmitters and charge pump on (FORCEOFF must be high) (Table 1). RS-232 Transmitter Outputs TTL/CMOS Noninverting Complementary Receiver Output. Always active. Force-Off Input, active low. Drive low to shut down transmitters, receivers (MAX3243E, except R2OUTB), and on-board charge pump. This overrides all automatic circuitry and FORCEON (Table 1). _______________Detailed Description Dual Charge-Pump Voltage Converter The MAX3221E/MAX3223E/MAX3243E’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), over the +3.0V to +5.5V VCC range. The charge pumps operate in discontinuous mode: if the output voltages are less than 5.5V, the charge pumps are enabled; 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. LapLink is a trademark of Traveling Software. 6 RS-232 Transmitters The transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. They guarantee a 250kbps data rate with worst-case loads of 3kΩ in parallel with 1000pF, providing compatibility with PC-to-PC communication software such as LapLink™. Transmitters can be paralleled to drive multiple receivers. The MAX3243E has been specifically designed to drive serial mice. Figure 1 shows a complete system connection. When FORCEOFF is driven to ground, or the AutoShutdown circuitry senses invalid voltage levels on all receiver inputs, the transmitters are disabled and the outputs are forced into a high-impedance state. When powered off or shut down, the output can be driven up to ±12V. The transmitter inputs do not have pull-up resistors. _______________________________________________________________________________________ ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown MAX3221E/MAX3223E/MAX3243E POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER VCC FORCEOFF FORCEON INVALID PROTECTION DIODE MAX3243E PREVIOUS RS-232 VCC I Rx 5k UART Tx CPU I/O CHIP WITH UART GND SHDN = GND RS-232 a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE RECEIVER OUTPUT IN SHUTDOWN. VCC TO LOGIC µP TRANSITION DETECTOR Figure 1. Interface Under Control of PMU I PROTECTION DIODE RS-232 Receivers The MAX3221E/MAX3223E/MAX3243E’s receivers convert RS-232 signals to CMOS-logic output levels. All receivers have inverting three-state outputs and can be active or inactive. In shutdown (FORCEOFF = low) or in AutoShutdown, the MAX3221E/MAX3223E’s receivers are active (Table 1). Drive EN high to place the receiver(s) in a high-impedance state. The MAX3243E’s receivers are high-impedance when the part is in shutdown (FORCEOFF = low). The MAX3243E features an extra, always-active complementary output (R2OUTB). R2OUTB monitors receiver activity while the other receivers are highimpedance. This allows Ring Indicator to be monitored without forward biasing other devices connected to the receiver outputs. This is ideal for systems where VCC drops to 0 in shutdown to accommodate peripherals such as UARTs (Figure 2). MAX3243E R2OUTB VCC Rx THREE-STATED UART 5k Tx GND b) R2IN R2OUT T1IN T1OUT FORCEOFF = GND NEW MAX3243E: IN SHUTDOWN, R2OUTB IS USED TO MONITOR EXTERNAL DEVICES AND R2OUT IS THREE STATED, ELIMINATING A CURRENT PATH THROUGH THE UART'S PROTECTION DIODE. Figure 2. The MAX3243E detects RS-232 activity when the UART and interface are shut down. _______________________________________________________________________________________ 7 MAX3221E/MAX3223E/MAX3243E ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown Table 1. Output Control Truth Table FORCEON FORCEOFF EN (MAX3221E/ MAX3223E) VALID RECEIVER LEVEL T_OUT R_OUT (MAX3221E/ MAX3223E) R_OUT (MAX3243E) R2OUTB (MAX3243E) Shutdown (Forced Off) X 0 0 X High-Z Active High-Z Active X 0 1 X High-Z High-Z High-Z Active Normal Operation (Forced On) 1 1 0 X Active Active Active Active 1 1 1 X Active High-Z Active Active Normal Operation (AutoShutdown) 0 1 0 Yes Active Active Active Active 0 1 1 Yes Active High-Z Active Active Shutdown (AutoShutdown) 0 1 0 No High-Z Active High-Z Active 0 1 1 No High-Z High-Z High-Z Active OPERATION STATUS X = Don’t Care +2.7V +0.3V R_IN -0.3V 30µs COUNTER R TO MAX32_ _E POWER SUPPLY AND TRANSMITTERS R_IN INVALID * TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1µA IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30µs. -2.7V 30µs COUNTER R TO MAX32_ _E POWER SUPPLY INVALID * TRANSMITTERS ARE ENABLED IF: ANY RECEIVER INPUT IS GREATER THAN +2.7V OR LESS THAN -2.7V. ANY RECEIVER INPUT HAS BEEN BETWEEN +0.3V AND -0.3V FOR LESS THAN 30µs. Figure 3a. MAX32_ _E Entering 1µA Supply Mode via AutoShutdown Figure 3b. MAX32__E with Transmitters Enabled Using AutoShutdown The MAX3221E/MAX3223E/MAX3243E feature an INVALID output that is enabled low when no valid RS-232 signal levels have been detected on all receiver inputs. INVALID is functional in any mode (Figures 3 and 5). signal levels on all receiver inputs for 30µs, the onboard charge pump and drivers are shut off, reducing supply current to 1µA. This occurs if the RS-232 cable is disconnected or the connected peripheral transmitters are turned off. The device turns on again when a valid level is applied to any RS-232 receiver input. As a result, the system saves power without changes to the existing BIOS or operating system. AutoShutdown The MAX3221E/MAX3223E/MAX3243E achieve a 1µA supply current with Maxim’s new AutoShutdown feature, which operates when FORCEON is low and FORCEOFF is high. When these devices sense no valid 8 _______________________________________________________________________________________ 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown™ POWER DOWN FORCEON INVALID Table 2. INVALID Truth Table RS-232 SIGNAL PRESENT AT ANY RECEIVER INPUT INVALID OUTPUT Yes High No Low INVALID IS AN INTERNALLY GENERATED SIGNAL THAT IS USED BY THE AUTOSHUTDOWN LOGIC AND APPEARS AS AN OUTPUT OF THE DEVICE. MAX3221E/MAX3223E/MAX3243E FORCEOFF POWER DOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES. Figure 3c. MAX32_ _E AutoShutdown Logic TRANSMITTERS ENABLED, INVALID HIGH MASTER SHDN LINE 0.1µF 1M FORCEOFF FORCEON MAX3221E MAX3223E MAX3243E +2.7V RECEIVER INPUT LEVELS POWERMANAGEMENT UNIT INDETERMINATE +0.3V 0 AUTOSHUTDOWN, TRANSMITTERS DISABLED, 1µA SUPPLY CURRENT, INVALID LOW -0.3V INDETERMINATE -2.7V TRANSMITTERS ENABLED, INVALID HIGH Figure 4. AutoShutdown with Initial Turn-On to Wake Up a Mouse or Another System Table 2 and Figure 3c summarize the MAX3221E/ MAX3223E/MAX3243E operating modes. FORCEON and FORCEOFF override AutoShutdown. When neither control is asserted, the IC selects between these states automatically, based on receiver input levels. Figures 3a, 3b, and 5a depict valid and invalid RS-232 receiver levels. Figure 5 shows the input levels and timing diagram for AutoShutdown operation. A mouse or other system with AutoShutdown may need time to wake up. Figure 4 shows a circuit that forces the transmitters on for 100ms, allowing enough time for the other system to realize that the MAX3221E/MAX3223E/ MAX3243E are awake. If the other system transmits valid RS-232 signals within that time, the RS-232 ports on both systems remain enabled. a) RECEIVER INPUT VOLTAGE (V) VCC INVALID OUTPUT (V) 0 Software-Controlled Shutdown tINVL tINVH tWU V+ VCC 0 When shut down, the device’s charge pumps are off, V+ is pulled to VCC, V- is pulled to ground, and the transmitter outputs are high impedance. The time required to exit shutdown is typically 100µs (Figure 5b). If direct software control is desired, INVALID can be used to indicate DTR or Ring Indicator signal. Connect FORCEOFF and FORCEON together to disable AutoShutdown so the line acts like a SHDN input. INVALID REGION V- b) Figure 5. AutoShutdown Trip Levels _______________________________________________________________________________________ 9 RC 1M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF RC 50M to 100M RD 1500Ω CHARGE CURRENT LIMIT RESISTOR DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR HIGHVOLTAGE DC SOURCE Cs 150pF RD 330Ω DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST Figure 7a. IEC1000-4-2 ESD Test Model Figure 6a. Human Body ESD Test Models I IP 100% 90% Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) 100% 90% AMPERES I PEAK MAX3221E/MAX3223E/MAX3243E ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Figure 6b. Human Body Model Current Waveform ±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the MAX3221E/MAX3223E/MAX3243E 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 an ESD event, Maxim’s E versions keep working without latchup, whereas competing RS-232 products can latch and must be powered down to remove 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) ±15kV using the Human Body Model 2) ±8kV using the contact-discharge method specified in IEC1000-4-2 3) ±15kV using IEC1000-4-2’s air-gap method 10 10% t r = 0.7ns to 1ns t 30ns 60ns Figure 7b. IEC1000-4-2 ESD Generator Current Waveform 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 6a shows the Human Body Model, and Figure 6b 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. IEC1000-4-2 The IEC1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The MAX3221E/ MAX3223E/MAX3243E help you design equipment that meets Level 4 (the highest level) of IEC1000-4-2, without the need for additional ESD-protection components. ______________________________________________________________________________________ ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown Table 3. Required Capacitor Values The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized. Table 4. Logic Family Compatibility with Various Supply Voltages Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. Of course, all pins require this protection during manufacturing, not just RS-232 inputs and outputs. Therefore, after PC board assembly, the Machine Model is less relevant to I/O ports. ___________Applications Information VCC (V) C1, CBYPASS (µF) C2, C3, C4 (µF) 0.22 3.0 to 3.6 0.22 3.15 to 3.6 0.1 0.1 4.5 to 5.5 0.047 0.33 3.0 to 5.5 0.22 1 SYSTEM POWERSUPPLY VOLTAGE (V) VCC SUPPLY VOLTAGE (V) COMPATIBILITY 3.3 3.3 Compatible with all CMOS families. 5 5 5 3.3 Compatible with all TTL and CMOS-logic families. Compatible with ACT and HCT CMOS, and with TTL. Incompatible with AC, HC, or CD4000 CMOS. Capacitor Selection The capacitor type used for C1–C4 is not critical for proper operation; either polarized or nonpolarized capacitors may be used. The charge pump requires 0.1µF capacitors for 3.3V operation. For other supply voltages, refer to Table 3 for required capacitor values. Do not use values smaller than those listed in Table 3. 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 larger nominal value. The capacitor’s equivalent series resistance (ESR) usually rises at low temperatures and influences the amount of ripple on V+ and V-. Power-Supply Decoupling In most circumstances, a 0.1µF VCC bypass capacitor is adequate. In applications that are sensitive to powersupply noise, use a capacitor of the same value as the charge-pump capacitor C1. Connect bypass capacitors as close to the IC as possible. FORCEON = FORCEOFF T2OUT 5V/div 2V/div T1OUT VCC = 3.3V C1–C4 = 0.1µF 40µs/div Figure 8. Transmitter Outputs Exiting Shutdown or Powering Up Transmitter Outputs when Exiting Shutdown Figure 8 shows two transmitter outputs when exiting shut down mode. As they become active, the two transmitter outputs are shown going to opposite RS-232 levels (one transmitter output 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, and are enabled only when the magnitude of Vexceeds approximately -3V. ______________________________________________________________________________________ 11 MAX3221E/MAX3223E/MAX3243E The major difference between tests done using the Human Body Model and IEC1000-4-2 is higher peak current in IEC1000-4-2, because series resistance is lower in the IEC1000-4-2 model. Hence, the ESD withstand voltage measured to IEC1000-4-2 is generally lower than that measured using the Human Body Model. Figure 7a shows the IEEE1000-4-2 model and Figure 7b shows the current waveform for the ±8kV IEC1000-4-2 Level 4 ESD contact-discharge test. High Data Rates The MAX3221E/MAX3223E/MAX3243E maintain the RS232 ±5.0V minimum transmitter output voltage even at high data rates. Figure 9 shows a transmitter loopback test circuit. Figure 10 shows a loopback test result at 120kbps, and Figure 11 shows the same test at 250kbps. For Figure 10, all three transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 11, a single transmitter was driven at 250kbps, and all three transmitters were loaded with an RS-232 receiver in parallel with 1000pF. VCC 0.1µF VCC C1+ V+ C3 C1 C1C2+ C2 C2- MAX3221E MAX3223E MAX3243E V- T1IN 5V/div T1OUT 5V/div C4 T_ OUT T_ IN R_ IN R_ OUT 0V Mouse Driveability (MAX3243E) The MAX3243E has been specifically designed to power serial mice while operating from low-voltage power supplies. It has been tested with leading mouse brands such as Logitech and Microsoft. When tested, the MAX3243E successfully drove all serial mice and met their respective current and voltage requirements. The MAX3243E’s regulated dual charge pump ensures the transmitters will supply at least ±5V during worst-case conditions. Figure 12a shows the transmitter outputs under increasing load current. The AutoShutdown feature does not work with a mouse, so FORCEOFF and FORCEON should be connected to VCC. Figure 12b (on the following page) shows a mouse driver test circuit. To achieve mouse driveability with 1µA supply current when the port is inactive, use parts with the AutoShutdown Plus feature (such as the MAX3244E and MAX3245E). EN (MAX3221/3E) 5k 5V/div R1OUT VCC = 3.3V 1000pF VCC FORCEOFF GND 2µs/div Figure 11. Loopback Test Result at 250kbps 5V/div T1IN 5V/div T1OUT 5V/div R1OUT VCC = 3.3V 6 5 4 VOUT+ VCC = 3.0V 3 2 1 MAX2343E-FIG15 Figure 9. Loopback Test Circuit TRANSMITTER OUTPUT VOLTAGE (V) MAX3221E/MAX3223E/MAX3243E ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown VOUT+ 0 -1 -2 VCC -3 -4 -5 -6 VOUTVOUT- 0 1 2 3 4 5 6 7 8 9 10 LOAD CURRENT PER TRANSMITTER (mA) 2µs/div Figure 10. Loopback Test Result at 120kbps 12 Figure 12a. Transmitter Output Voltage vs. Load Current per Transmitter ______________________________________________________________________________________ ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown MAX3221E/MAX3223E/MAX3243E +3.3V 26 0.1µF 28 C1 0.1µF 24 1 C2 0.1µF 2 LOGIC INPUTS VCC 27 C1+ V+ C3 0.1µF C1C2+ COMPUTER SERIAL PORT 3 MAX3243E V- C4 0.1µF C2- 14 T1IN T1OUT 9 +V 13 T2IN T2OUT 10 +V 12 T3IN T3OUT 11 -V 20 R2OUTB 19 R1OUT GND R1IN 4 R2IN 5 R3IN 6 R4IN 7 R5IN 8 Tx 5k 18 R2OUT LOGIC OUTPUTS 5k 17 R3OUT RS-232 INPUTS 5k 16 R4OUT 5k 15 VCC VCC TO POWERMANAGEMENT UNIT 23 22 21 R5OUT SERIAL MOUSE 5k FORCEON FORCEOFF INVALID GND 25 Figure 12b. Mouse Driver Test Circuit ______________________________________________________________________________________ 13 MAX3221E/MAX3223E/MAX3243E ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown Interconnection with 3V and 5V Logic HCT CMOS. See Table 4 for more information on possible combinations of interconnections. The MAX3221E/MAX3223E/MAX3243E can directly interface with various 5V logic families, including ACT and Table 5. ±15kV ESD-Protected, 3.0V to 5.5V Powered RS-232 Transceivers from Maxim PART Supply Voltage Range (V) No. of Tx/Rx Human Body Model (kV) IEC 1000-4-2 Contact Discharge (kV) IEC 1000-4-2 Air-Gap Discharge (kV) Guaranteed Data Rate (kbps) MAX3241E +3.0 to +5.5 3/5 300 — MAX3243E +3.0 to +5.5 3/5 1 — — ±15 ±8 ±15 250 Yes ±15 ±8 ±15 MAX3244E +3.0 to +5.5 3/5 1 Yes 250 — ±15 ±8 ±15 MAX3245E +3.0 to +5.5 3/5 1 250 Yes — ±15 ±8 ±15 1Mbps MAX3232E +3.0 to +5.5 2/2 300 — — ±15 ±8 ±15 250 MAX3222E +3.0 to +5.5 MAX3223E +3.0 to +5.5 2/2 300 — — ±15 ±8 ±15 250 2/2 1 — Yes ±15 ±8 ±15 MAX3224E 250 +3.0 to +5.5 2/2 1 Yes — ±15 ±8 ±15 250 MAX3225E +3.0 to +5.5 2/2 1 Yes — ±15 ±8 ±15 1Mbps MAX3221E +3.0 to +5.5 1/1 1 — Yes ±15 ±8 ±15 250 MAX3226E +3.0 to +5.5 1/1 1 Yes — ±15 ±8 ±15 250 MAX3227E +3.0 to +5.5 1/1 1 Yes — ±15 ±8 ±15 1Mbps Supply AutoAutoCurrent Shutdown Shutdown (µA) Plus ___________________Chip Information MAX3221E TRANSISTOR COUNT: 269 MAX3223E TRANSISTOR COUNT: 339 MAX3243E TRANSISTOR COUNT: 476 14 ______________________________________________________________________________________ ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown +3.3V 15 0.1µF CBYPASS 2 C1+ C1 0.1µF 4 C15 C2 0.1µF 6 VCC 3 V+ C3 0.1µF MAX3221E C2+ 7 V- C4 0.1µF C2- 11 T1IN +3.3V CBYPASS 28 C1+ C1 0.1µF T1OUT 13 24 1 C2 0.1µF R1IN 8 9 R1OUT 2 5k 12 TO POWERMANAGEMENT UNIT INVALID 10 1 EN FORCEOFF 16 FORCEON GND LOGIC INPUTS MAX3243E V- 2 C1+ 4 6 C1- MAX3223E C2+ V- C3 0.1µF 7 14 T1IN T1OUT 9 13 T2IN T2OUT 10 12 T3IN T3OUT 11 R1IN 4 R2IN 17 R3OUT R3IN 6 5k 15 R5OUT 23 R1IN 16 R2IN RS-232 INPUTS INVALID 11 1 EN FORCEOFF 20 FORCEON GND VCC 9 TO POWERMANAGEMENT UNIT 5k RS-232 INPUTS R4IN 7 RS-232 OUTPUTS 5k 5 5k 16 R4OUT T2OUT 8 10 R2OUT RS-232 OUTPUTS 5k T1OUT 17 TTL/CMOS OUTPUTS 14 LOGIC OUTPUTS C4 0.1µF C2- 15 R1OUT C4 0.1µF C2- 18 R2OUT 3 V+ 12 T2IN 3 5k VCC 13 T1IN TTL/CMOS INPUTS C2+ 19 0.1µF C3 0.1µF C1- 19 R1OUT 5 C2 0.1µF 27 V+ 20 R2OUTB +3.3V C1 0.1µF VCC VCC 14 CBYPASS 26 0.1µF 22 R5IN 8 5k FORCEON FORCEOFF 21 INVALID GND 25 TO POWERMANAGEMENT UNIT VCC 18 ______________________________________________________________________________________ 15 MAX3221E/MAX3223E/MAX3243E Typical Operating Circuits MAX3221E/MAX3223E/MAX3243E ±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps, RS-232 Transceivers with AutoShutdown Pin Configurations TOP VIEW EN 1 EN 1 V+ 3 C1- 4 19 VCC 15 VCC V+ 3 18 GND 14 GND C1- 4 13 T1OUT C2+ 5 12 FORCEON C2- 6 16 FORCEOFF C1+ 2 MAX3221E C2+ 5 C2- 6 V- 7 17 T1OUT MAX3223E 10 INVALID 16 R1IN 15 R1OUT V- 7 11 T1IN 14 FORCEON T2OUT 8 13 T1IN R2IN 9 12 T2IN 9 R1OUT R1IN 8 20 FORCEOFF C1+ 2 R2OUT 10 11 INVALID SSOP DIP/SSOP C2+ 1 28 C1+ C2- 2 27 V+ V- 3 26 VCC R1IN 4 25 GND R2IN 5 R3IN 6 MAX3243E 24 C123 FORCEON R4IN 7 22 FORCEOFF R5IN 8 21 INVALID T1OUT 9 20 R2OUTB T2OUT 10 19 R1OUT T3OUT 11 18 R2OUT T3IN 12 17 R3OUT T2IN 13 16 R4OUT T1IN 14 15 R5OUT SO/SSOP 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 © 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.