19-0306; Rev 6; 3/99 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown The MAX3221/MAX3223/MAX3243 require only 0.1µF capacitors in 3.3V operation, and can operate from input voltages ranging from +3.0V to +5.5V. They are ideal for 3.3V-only systems, mixed 3.3V and 5.0V systems, or 5.0V-only systems that require true RS-232 performance. The MAX3221 is a 1-driver/1-receiver 16-pin SSOP version of the 20-pin MAX3223 (2-driver/2-receiver). The MAX3243 3-driver/5-receiver, complete serial port is ideal for notebook or subnotebook computers. The MAX3243 includes one complementary always-active receiver. This receiver can monitor an external device (such as a modem) in shutdown, without forward biasing the protection diodes in a UART that may have VCC completely removed. MAX3221 Tx 1 Rx 1 ♦ Small 0.1µF Capacitors ♦ True RS-232 Operation from VCC = +3.0V to +5.5V ♦ Meets EIA/TIA-562 Specifications Down to 2.7V ♦ Guaranteed 120kbps Data Rate ♦ 6V/µs Min Guaranteed Slew Rate ♦ Smallest Single-Supply RS-232 Transceiver (MAX3221) ♦ Guaranteed Mouse Driveability (MAX3243) ♦ Small TSSOP Package (MAX3223/MAX3243) ________________________Applications Notebook, Subnotebook, and Palmtop Computers Battery-Powered Equipment Hand-Held Equipment Peripherals Printers ______________Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX3221CAE 0°C to +70°C 16 SSOP 0°C to +70°C 16 TSSOP MAX3221CUE† MAX3221EAE -40°C to +85°C MAX3221EUE† -40°C to +85°C 16 SSOP 16 TSSOP 0°C to +70°C 20 Plastic DIP MAX3223CAP 0°C to +70°C 20 SSOP MAX3223CUP 0°C to +70°C 20 TSSOP Yes MAX3223EPP -40°C to +85°C 20 Plastic DIP -40°C to +85°C 20 SSOP 20 TSSOP VCC RANGE (V) AutoShutdown 3.0 to 5.5 ♦ 1µA Supply Current Achieved with AutoShutdown MAX3223CPP _____________________Selector Guide PART ____________________________Features MAX3223 2 2 3.0 to 5.5 Yes MAX3223EAP MAX3243 3 5 3.0 to 5.5 Yes MAX3223EUP -40°C to +85°C MAX3243CWI 0°C to +70°C 28 Wide SO MAX3243CAI 0°C to +70°C 28 SSOP MAX3243CUI 0°C to +70°C 28 TSSOP MAX3243EWI -40°C to +85°C 28 Wide SO MAX3243EAI -40°C to +85°C 28 SSOP MAX3243EUI -40°C to +85°C 28 TSSOP Pin Configurations appear at end of data sheet. Typical Operating Circuits appear at end of data sheet. †Future product—contact factory for availability. 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; 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. MAX3221/MAX3223/MAX3243* _______________General Description The MAX3221/MAX3223/MAX3243 achieve 1µA supply current with Maxim’s revolutionary AutoShutdown™ feature. When the MAX3221/MAX3223/MAX3243 do not sense a valid signal level on their receiver inputs, the on-board power supply and drivers shut down. This occurs if the RS-232 cable is disconnected or if the transmitters of the connected peripheral are turned off. The system 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. The MAX3221/MAX3223/MAX3243 transceivers are 3Vpowered EIA/TIA-232 and V.28/V.24 communications interfaces intended for notebook computer applications. A proprietary, high-efficiency, dual charge-pump power supply and a low-dropout transmitter combine to deliver true RS-232 performance from a single +3.0V to +5.5V supply. A guaranteed data rate of 120kbps provides compatibility with popular software for communicating with personal computers. MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown ABSOLUTE MAXIMUM RATINGS 16-Pin SSOP (derate 7.14mW/°C above +70°C) ...........571mW 16-Pin TSSOP (derate 6.70mW/°C above +70°C) .........533mW 20-Pin Plastic DIP (derate 11.11mW/°C above +70°C)....889mW 20-Pin SSOP (derate 8.00mW/°C above +70°C) ...........640mW 20-Pin TSSOP DIP (derate 7.00mW/°C above +70°C).....559mW 28-Pin Wide SO (derate 12.50mW/°C above +70°C) ............1W 28-Pin SSOP (derate 9.52mW/°C above +70°C) ...........762mW 28-Pin TSSOP (derate 8.70mW/°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, FORCEOFF, FORCEON, EN (MAX3223) ......-0.3V to +6V R_IN ...................................................................................±25V Output Voltages T_OUT.............................................................................±13.2V R_OUT, INVALID ......................................-0.3V to (VCC + 0.3V) Short-Circuit Duration T_OUT ......................................................................Continuous Continuous Power Dissipation (TA = +70°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 CONDITIONS MIN TYP MAX UNITS 1.0 10 µA 1.0 10 µA 0.3 1.0 mA 0.8 V DC CHARACTERISTICS Supply Current, AutoShutdown Supply Current, Shutdown Supply Current, AutoShutdown Disabled All R_IN open, FORCEON = GND, VCC = 3.3V FORCEOFF = VCC or 5.0V, FORCEOFF = GND TA = +25°C FORCEON = FORCEOFF = V , CC no load LOGIC INPUTS AND RECEIVER OUTPUTS Input Logic Threshold Low T_IN, FORCEON, FORCEOFF, EN (MAX3223) VCC = 3.3V 2.0 VCC = 5.0V 2.4 Input Logic Threshold High T_IN, EN, FORCEON, FORCEOFF Input Leakage Current T_IN, EN, FORCEON, FORCEOFF ±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 AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC) Positive threshold Receiver Input Thresholds to Transmitters Enabled Figure 5 Receiver Input Thresholds to Transmitters Disabled 1µA supply current, Figure 5 INVALID Output Voltage Low IOUT = 1.6mA INVALID Output Voltage High IOUT = -1.0mA Receiver Threshold to Transmitters Enabled (tWU) Receiver Positive or Negative Threshold to INVALID High (tINVH) Receiver Positive or Negative Threshold to INVALID Low (tINVL) 2 Negative threshold 2.7 -2.7 -0.3 VCC - 0.6 V 0.3 V 0.4 V V Figure 5 250 µs Figure 5 1 µs Figure 5 30 µs _______________________________________________________________________________________ 1µA Supply-Current, True +3V to +5.5V 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 CONDITIONS MIN TYP MAX UNITS 25 V RECEIVER INPUTS Input Voltage Range -25 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 0.3 Input Resistance TA = +25°C 3 5 V 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, transmitter output = ±2V 300 10M Output Short-Circuit Current Output Leakage Current ±35 VOUT = ±12V, VCC = 0V or 3.0V to 5.5V, transmitters disabled V Ω ±60 mA ±25 µA MOUSE DRIVEABILITY (MAX3243) Transmitter Output Voltage T1IN = T2IN = GND, T3IN = VCC, T3OUT loaded with 3kΩ to GND, T1OUT and T2OUT loaded with 2.5mA each ±5 RL = 3kΩ, CL = 1000pF, one transmitter switching 120 V TIMING CHARACTERISTICS Maximum Data Rate 235 tPHL 0.3 tPLH 0.3 kbps Receiver Propagation Delay Receiver input to receiver output, CL = 150pF Receiver Output Enable Time Normal operation 200 ns Receiver Output Disable Time Normal operation 200 ns Transmitter Skew Receiver Skew Transition-Region Slew Rate µs tPHL - tPLH MAX3221/MAX3223 200 MAX3243 200 tPHL - tPLH MAX3221/MAX3223 100 MAX3243 100 500 8.0 30 VCC = 3.3V, RL = 3kΩ to 7kΩ, TA = +25°C, measured from +3V to -3V or -3V to +3V CL = 200pF to 2500pF 4 1000 ns ns V/µs CL = 200pF to 1000pF 6 30 Note 2: C1–C4 = 0.1µF, tested at 3.3V ±10%. C1 = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%. _______________________________________________________________________________________ 3 MAX3221/MAX3223/MAX3243 ELECTRICAL CHARACTERISTICS (continued) __________________________________________Typical Operating Characteristics (VCC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, TA = +25°C, unless otherwise noted.) 20 18 SLEW RATE (V/µs) 4 3 2 1 0 -1 -2 -3 MAX3221/3223-02 VOUT+ 16 14 -SLEW 12 10 +SLEW 8 6 -4 4 VOUT- FOR DATA RATES UP TO 235kbps 35 35 30 235kbps 30 25 25 20 120kbps 20 15 15 10 20kbps 10 5 2 1000 2000 3000 4000 4000 MAX3243 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE MAX3243 SLEW RATE vs. LOAD CAPACITANCE 22 20 1 TRANSMITTER AT 235kbps 2 TRANSMITTERS AT 30kbps -2.5 VOUT- -5.0 18 14 12 +SLEW ALL OUTPUTS LOADED WITH 3kΩ +CL 0.1µF CHARGE-PUMP CAPACITORS FOR ALL DATA RATES UP TO 235kbps 6 4 -7.5 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 5000 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 2000 3000 4000 5000 MAX3243 SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA -SLEW 8 1000 LOAD CAPACITANCE (pF) 16 10 0 0 5000 MAX3221/3223-05 24 SLEW RATE (V/µs) 5.0 0 3000 LOAD CAPACITANCE (pF) VOUT+ 0 5 2000 LOAD CAPACITANCE (pF) 7.5 2.5 0 150 500 1000 5000 MAX3221/3223-04 0 45 235kbps 40 35 30 MAX3221/3223-06 -6 SUPPLY CURRENT (mA) -5 4 MAX3221/3223-03 40 MAX3223 SUPPLY CURRENT (mA) 22 MAX3221/3223-01 TRANSMITTER OUTPUT VOLTAGE (V) 6 5 MAX3221/MAX3223 SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA MAX3221/MAX3223 SLEW RATE vs. LOAD CAPACITANCE 120kbps 25 20 20kbps 15 10 5 0 5000 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 5000 MAX3221 SUPPLY CURRENT (mA) MAX3221/MAX3223 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE TRANSMITTER OUTPUT VOLTAGE (V) MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown PIN NAME FUNCTION — EN Receiver Enable Control. Drive low for normal operation. Drive high to force the receiver outputs into a high-Z state. 5 1 C2+ Positive terminal of inverting charge-pump capacitor 6 2 C2- Negative terminal of inverting charge-pump capacitor 7 7 3 V- 8 9, 16 4–8 R_IN 13 8, 17 9, 10, 11 T_OUT 11 12, 13 12, 13, 14 T_IN TTL/CMOS Transmitter Inputs 9 10, 15 15–19 R_OUT TTL/CMOS Receiver Outputs — — 20 R2OUTB Noninverting Receiver Output—active in shutdown 10 11 21 INVALID Output of the valid signal detector. Indicates if a valid RS-232 level is present on receiver inputs logic “1”. 16 20 22 FORCEOFF Drive low to shut down transmitters and on-board power supply. This overrides all automatic circuitry and FORCEON (Table 1). 12 14 23 FORCEON Drive high to override automatic circuitry keeping transmitters on (FORCEOFF must be high) (Table 1). 4 4 24 C1- Negative terminal of the voltage doubler charge-pump capacitor 14 18 25 GND Ground 15 19 26 VCC +3.0V to +5.5V Supply Voltage 3 3 27 V+ +5.5V generated by the charge pump 2 2 28 C1+ MAX3221 MAX3223 MAX3243 1 1 5 6 -5.5V generated by the charge pump RS-232 Receiver Inputs RS-232 Transmitter Outputs Positive terminal of the voltage doubler charge-pump capacitor _______________Detailed Description Dual Charge-Pump Voltage Converter The MAX3221/MAX3223/MAX3243’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 (V CC) 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; 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. They guarantee a 120kbps data rate with worst-case loads of 3kΩ in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as Laplink™). Typically, the MAX3221/MAX3223/MAX3243 can operate at data rates of 235kbps. Transmitters can be paralleled to drive multiple receivers or mice (MAX3243). Figure 1 shows a complete system connection. When FORCEOFF is driven to ground, or the AutoShutdown circuitry senses invalid voltage levels at all receiver inputs, the transmitters are disabled and the outputs are forced into a high-impedance state. LapLink is a trademark of Traveling Software. _______________________________________________________________________________________ 5 MAX3221/MAX3223/MAX3243 ______________________________________________________________Pin Description MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown POWER MANAGEMENT UNIT OR KEYBOARD CONTROLLER FORCEOFF VCC FORCEON INVALID PROTECTION DIODE PREVIOUS RS-232 MAX3243 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 µP LOGIC TRANSITION DETECTOR Figure 1. Interface Under Control of PMU I PROTECTION DIODE RS-232 Receivers The MAX3221/MAX3223/MAX3243’s receivers convert RS-232 signals to CMOS-logic output levels. All receivers have one inverting three-state output. In shutdown (FORCEOFF = low) or in AutoShutdown, the MAX3221/MAX3223’s receivers are active (Table 1). Driving EN high places the receiver(s) in a high-impedance state. The MAX3243’s receivers are high impedance when the part is shut down. The MAX3243 has an always-active complementary output (R2OUTB). R2OUTB is an extra output that monitors receiver activity while the other receivers are high impedance. This allows Ring Indicator to be monitored without forward biasing other devices connected to the receiver outputs. This is ideal for systems where VCC is set to 0V in shutdown to accommodate peripherals, such as UARTs (Figure 2). 6 MAX3243 R2OUTB VCC Rx THREE-STATED UART 5k Tx GND (b) R2IN R2OUT T1IN FORCEOFF = GND NEW MAX3243: 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 MAX3243 detects RS-232 activity when the UART and interface are shut down. _______________________________________________________________________________________ T1OUT 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown FORCEOFF EN T_OUT R_OUT 0 0 High-Z Active 0 1 High-Z 1 0 Active* High-Z Active 1 1 Active* High-Z MAX3221/MAX3223/MAX3243 Table 1a. MAX3221/MAX3223 FORCEOFF and Enable Control Truth Table +0.3V R_IN 30µs COUNTER R -0.3V TO MAX32_ _ POWER SUPPLY AND TRANSMITTERS INVALID * TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1µA IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30µs. Figure 3a. MAX32_ _ Entering 1µA Supply Mode via AutoShutdown Table 1b. MAX3243 FORCEOFF Control Truth Table FORCEOFF T_OUT R_OUT R2OUTB 0 High-Z High-Z Active 1 Active* Active* Active *Note: If the part is in AutoShutdown mode (FORCEOFF = VCC, FORCEON = GND), it is shut down if no valid RS-232 levels are present on all receiver inputs. AutoShutdown A 1µA supply current is achieved with Maxim’s new AutoShutdown feature, which operates when FORCEON is low and FORCEOFF is high. When the MAX3221/MAX3223/MAX3243 sense no valid signal levels on all receiver inputs for 30µs, the on-board power supply 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 system 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. When using AutoShutdown, the INVALID output is high when the device is on and low when the device is shut down. Because INVALID indicates the receiver inputs’ condition, it can be used in any mode (Figure 3). Table 2 and Figure 3c summarize the MAX3221/ MAX3223/MAX3243 operating modes. FORCEON and FORCEOFF override the automatic circuitry and force the transceiver into its normal operating state or into its low-power standby state. 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. 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 +2.7V R_IN TO MAX32_ _ POWER SUPPLY 30µs COUNTER R -2.7V 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 3b. MAX32_ _ with Transmitters Enabled Using AutoShutdown FORCEOFF POWER DOWN FORCEON INVALID INVALID IS AN INTERNALLY GENERATED SIGNAL THAT IS USED BY THE AUTOSHUTDOWN LOGIC AND APPEARS AS AN OUTPUT OF THE DEVICE. POWER DOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES. Figure 3c. AutoShutdown Logic POWER MANAGEMENT UNIT MASTER SHDN LINE 0.1µF 1M FORCEOFF FORCEON MAX3221 MAX3223 MAX3243 Figure 4. AutoShutdown with Initial Turn-On to Wake Up a Mouse or Another System _______________________________________________________________________________________ 7 Table 2. AutoShutdown Logic RS-232 SIGNAL PRESENT AT RECEIVER INPUT FORCEOFF INPUT Yes No FORCEON INPUT INVALID OUTPUT H X H Normal Operation H H L Normal Operation (Forced On) TRANSCEIVER STATUS No H L L Shutdown (AutoShutdown) Yes L X H Shutdown (Forced Off) No L X L Shutdown (Forced Off) other system to realize that the MAX3221/MAX3223/ MAX3243 is awake. If the other system outputs valid RS-232 signals within that time, the RS-232 ports on both systems remain enabled. When shut down, the device’s charge pumps are turned off, V+ decays to VCC, V- decays to ground, and the transmitter outputs are disabled (high impedance). The time required to exit shutdown is typically 100µs (Figure 5b). TRANSMITTERS ENABLED, INVALID HIGH RECEIVER INPUT LEVELS MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown +2.7V INDETERMINATE +0.3V 0V -0.3V INDETERMINATE Software-Controlled Shutdown If direct software control is desired, INVALID can be used to indicate DTR or Ring Indicator signal. Tie FORCEOFF and FORCEON together to bypass AutoShutdown so the line acts like a SHDN input. AUTOSHUTDOWN, TRANSMITTERS DISABLED, 1µA SUPPLY CURRENT, INVALID LOW -2.7V TRANSMITTERS ENABLED, INVALID HIGH (a) ___________Applications Information 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-. 8 RECEIVER INPUT VOLTAGE (V) INVALID REGION VCC INVALID OUTPUT (V) 0 tINVL tINVH tWU V+ VCC 0 V- (b) Figure 5. AutoShutdown Trip Levels _______________________________________________________________________________________ 2V/div T1 50µs/div 4 3 T1 0 -1 T2 VOUT+ -2 -3 VCC VOUT- T3 VOUT- -4 -5 -6 0 VCC = +3.3V C1–C4 = 0.1µF VOUT+ VCC = 3.0V 2 1 MAX3222-04 T2 6 5 1 2 3 4 5 6 7 LOAD CURRENT PER TRANSMITTER (mA) Figure 6. Transmitter Outputs when Exiting Shutdown or Powering Up 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 the charge-pump capacitor C1. Connect bypass capacitors as close to the IC as possible. Transmitter Outputs when Exiting Shutdown Figure 6 shows two transmitter outputs when exiting shutdown mode. As they become active, the two transmitter outputs are shown going to opposite RS-232 levels. 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. Figure 7a shows the MAX3243’s transmitter output voltage vs. current per transmitter. Figure 7b is a mouse driver test circuit. Figure 7a. MAX3243 Transmitter Output Voltage vs. Load Current per Transmitter Microsoft. The MAX3243 successfully drove all serial mice and met their respective current and voltage requirements. Figure 7a shows the transmitter outputs under increasing load current. The MAX3243’s switching regulator ensures the transmitters will supply at least ±5V during worst-case conditions. The AutoShutdown feature does not work with a mouse, so FORCEOFF and FORCEON should be connected to VCC. High Data Rates The MAX3221/MAX3223/MAX3243 maintain the RS-232 ±5.0V minimum transmitter output voltage even at high data rates. Figure 8 shows a transmitter loopback test circuit. Figure 9 shows a loopback test result at 120kbps, and Figure 10 shows the same test at 235kbps. For Figure 9, all three transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 10, a single transmitter was driven at 235kbps, but all three transmitters were loaded with an RS-232 receiver in parallel with 1000pF. Mouse Driveability (MAX3243) Interconnection with 3V and 5V Logic The MAX3243 has been specifically designed to power serial mice while operating from low-voltage power supplies. It has been tested with samples of ten major mouse models from six manufacturers including the leading three: Logitech (5 models), Mouse Systems, and The MAX3221/MAX3223/MAX3243 can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 4 for more information on possible combinations of interconnections. _______________________________________________________________________________________ 9 MAX3221/MAX3223/MAX3243 5V/div TRANSMITTER OUTPUT VOLTAGE (V) 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown +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 MAX3243 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 23 VCC TO POWER MANAGEMENT UNIT 22 21 R5OUT SERIAL MOUSE 5k FORCEON FORCEOFF INVALID GND 25 Figure 7b. Mouse Driver Test Circuit 10 ______________________________________________________________________________________ 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown VCC (V) 0.1µF VCC C1+ V+ C3 C1 C1 (µF) C2, C3, C4 (µF) 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 C1C2+ MAX3221 MAX3223 MAX3243 C2 C2- R_ IN R_ OUT VCC C4 T_ OUT T_ IN 0V V- EN (MAX3221/3) FORCEOFF 5k Table 4. Logic Family Compatibility with Various Supply Voltages SYSTEM POWERSUPPLY VOLTAGE (V) VCC SUPPLY VOLTAGE (V) 3.3 3.3 5 5 5 3.3 1000pF GND 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, or CD4000 CMOS. Figure 8. Loopback Test Circuit T1IN 5V/div T1IN 5V/div T1OUT 5V/div T1OUT 5V/div R1OUT 5V/div R1OUT 5V/div 5µs/div VCC = +3.3V, 120kbps C1–C4 = 0.1µF Figure 9. Loopback Test Result at 120kbps 2µs/div VCC = +3.3V, 235kbps C1–C4 = 0.1µF Figure 10. Loopback Test Result at 235kbps ______________________________________________________________________________________ 11 MAX3221/MAX3223/MAX3243 Table 3. Required Capacitor Values VCC MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown __________________________________________________Typical Operating Circuits +3.3V 15 0.1µF C5 2 C1+ C1 0.1µF 4 C15 C2 0.1µF 6 VCC 3 V+ MAX3221 C2+ V- C3 0.1µF 28 C1+ C1 0.1µF T1OUT 13 24 1 C2 0.1µF R1IN 8 9 R1OUT 2 5k 1 EN 12 INVALID 10 FORCEOFF 16 FORCEON GND TO POWER MANAGEMENT UNIT LOGIC INPUTS TTL/CMOS INPUTS C2+ MAX3243 V- 2 C1+ 4 C1- 6 14 T1IN T1OUT 9 13 T2IN T2OUT 10 12 T3IN T3OUT 11 MAX3223 C2+ V- C3 0.1µF 7 C2- 13 T1IN T1OUT 17 12 T2IN T2OUT 8 LOGIC OUTPUTS C4 0.1µF 17 R3OUT R3IN 6 5k R4IN 7 RS-232 OUTPUTS 5k 23 R1IN 16 RS-232 INPUTS VCC R2IN 9 TO POWER MANAGEMENT UNIT 5k 1 EN INVALID 11 FORCEOFF 20 FORCEON GND 22 R5IN 8 5k FORCEON FORCEOFF 21 INVALID GND 25 TO POWER MANAGEMENT UNIT VCC 18 12 5 5k 16 R4OUT 5k 14 R2IN 15 R5OUT 10 R2OUT RS-232 OUTPUTS R1IN 4 18 R2OUT 3 V+ TTL/CMOS OUTPUTS C4 0.1µF 5k VCC 15 R1OUT 3 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 C5 26 0.1µF C4 0.1µF C2- 11 T1IN +3.3V 7 ______________________________________________________________________________________ RS-232 INPUTS 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown PART POWERSUPPLY VOLTAGE (V) No. OF TRANSMITTERS/ RECEIVERS No. OF RECEIVERS ACTIVE IN SHUTDOWN GUARANTEED DATA RATE (kbps) EIA/TIA232 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 2 230 120 562 562 230kbps guaranteed data rate 0.1µF capacitors MAX3212 2.7 to 3.6 3/5 5 235 232 AutoShutdown, complementary receiver, drives mice, transient detection MAX3221 MAX3222 MAX3223 MAX3232 3.0 to 5.5 3.0 to 5.5 3.0 to 5.5 3.0 to 5.5 1/1 2/2 2/2 2/2 1 2 2 N/A 120 120 120 120 232 232 232 232 0.1µF capacitors, 16-pin SSOP 0.1µF capacitors, MAX242 pinout 0.1µF capacitors, AutoShutdown 0.1µF capacitors, MAX232 pinout 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 ______________________________________________________________________________________ 13 MAX3221/MAX3223/MAX3243 ______3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown __________________________________________________________Pin Configurations TOP VIEW EN 1 EN 1 16 FORCEOFF C1+ 2 15 VCC V+ 3 14 GND C1- 4 MAX3221 13 T1OUT V+ 3 18 GND C2+ 5 12 FORCEON C2- 6 11 T1IN C2- 6 V- 7 10 INVALID C2+ 1 28 C1+ C2- 2 27 V+ V- 3 26 VCC R1IN 4 25 GND R2IN 5 MAX3243 R3IN 6 16 R1IN 15 R1OUT 14 FORCEON 13 T1IN R2IN 9 12 T2IN R2OUT 10 SSOP/TSSOP 17 T1OUT MAX3223 T2OUT 8 9 R1OUT R1IN 8 19 VCC C1- 4 C2+ 5 V- 7 20 FORCEOFF C1+ 2 11 INVALID DIP/SSOP/TSSOP 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/TSSOP ___________________Chip Information MAX3221 TRANSISTOR COUNT: 269 MAX3223 TRANSISTOR COUNT: 339 MAX3243 TRANSISTOR COUNT: 476 14 ______________________________________________________________________________________ 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown TSSOP.EPS SSOP.EPS ______________________________________________________________________________________ 15 MAX3221/MAX3223/MAX3243 ________________________________________________________Package Information SOICW.EPS ___________________________________________Package Information (continued) PDIPN.EPS MAX3221/MAX3223/MAX3243 1µA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown 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.