19-0306; Rev 4; 10/96 MA AXISA 1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown General Description The MAX3221/MAX3223/MAX3243 achieve 1pA supply current with Maxim's revolutionary AutoShutdown fea- ture. 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 3V- powered EIA/TIA-232 and V.28/V.24 communications interfaces intended for notebook computer applica- tions. 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 pro- vides compatibility with popular software for communi- cating with personal computers. The MAX3221/MAX3223/MAX3243 require only 0.1uF 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 Features @ 1pA Supply Current Achieved with AutoShutdown Small 0.1pF Capacitors @ True RS-232 Operation from Vcc = 3.0V to 5.5V @ Meets ElA/TIA-562 Specifications Down to 2.7V # Guaranteed 120kbps Data Rate @ 6V/us Min Guaranteed Slew Rate Smallest Single-Supply RS-232 Transceiver (MAX3221) # Guaranteed Mouse Driveability (MAX3243) Applications Notebook, Subnotebook, and Palmtop Computers Battery-Powered Equipment Hand-Held Equipment sEPZEXVIW/ECTEXVW/ICCEXVUWN 5.0V-only systems that require true RS-232 performance. Peripherals The MAX3221 is a 1-driver/1-receiver 16-pin SSOP ver- sion of the 20-pin MAX3223 (2-driver/2-receiver). The Printers MAX3243 3-driver/5-receiver, complete serial port is idea] for notebook or subnotebook computers. The MAX3243 includes one complementary always-active receiver. This receiver can monitor an external device Ordering Information (such as a modem) in shutdown, without forward bias- ing the protection diodes in a UART that may have Vcc PART TEMP.RANGE PIN-PACKAGE completely removed. MAX3221CAE OC to +70C 16 SSOP MAX3221EAE -40C to +85C 16 SSOP MAX3223CPP 0C to +70C 20 Plastic DIP MAX3223CAP OC to +70C 20 SSOP Selector Guide MAX3223EPP -40C to +85C 20 Plastic DIP MAX3223EAP ~40C to +85C 20 SSOP PART Rx |Vcc RANGE (V) | AuteShutdown MAX3243CWi OC to +70C 2B Wide SO MAX322 1 1 1 3.0 to .5 Yes MAX3243CAl OPC to +70C 28 SSOP MAX3223 2 2 3.010 5.5 Yes MAX3243EW! -40C to +85C 28 Wide SO MAX3243 3 5 3.0 to 5.5 Yes MAX3243EAI ~40C to +85C 28 SSOP AutoShutdown is a trademark of Maxim Integrated Products. Pin Contigurations appeer at end of data sheet. Typical Operating Circuits appear at end of data sheet. * 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 penaing. MAAXILMA Maxim Integrated Products 2-123 For free samples & the latest literature: http:/;www.maxim-ic.com, or phone 1-800-998-8800MAX3221/MAX3223/MAX3243 2-124 1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown ABSOLUTE MAXIMUM RATINGS VCC veccccceecesscscercereesesseeeseestateesenrees V+ (Note 1)... V- (Note 1)... V+ + IV-L (Note 1) ccc eee Input Voltages Output Voltages TOUT oo eccccccceeeteteteeteeees R_OUT, INVALID oe Short-Circuit Duration dev actateeeterenessaty -0.3V to +6V Continuous Power Dissipation (Ta = +70C) -0.3V to +7V 16-Pin SSOP (derate 7.14mW/C above +70C) ...0...... 571mW .+0.3V to -7V 20-Pin Plastic DIP (derate 11.41mW/C above +70C)....889mW ceeds eet es eeascaetsteeesees +13V 20-Pin SSOP (derate 8.COmW/C above +70C) ...........640mW 28-Pin Wide SO (derate 12.50mMW/C above +70C)............ Iw (MAX3223) ......-0.3V to +6V 28-Pin SSOP (derate 9.52mW/C above +70C) ........... 762mW bev deteneee re eeceeaeneoneceenaes +25V Operating Temperature Ranges MAX32_ Co ec cccescceceseteteterecsersestntrens 10C to +70C doce eveeneaentenevaees +13.2V MAX32_ Eo ee eccccseeeereccees 40C to +85C betteeeeees -0.3V to (Vec + 0.3V) baieettsetetteettenteeaes Continuous Storage Temperature Range ......... Lead Temperature (soldering, 10sec) Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V. 66C to +150C 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 .5V, C1-C4 = 0.1pF (Note 2), Ta = TMIN to TMax, unless otherwise noted. Typical values are at Ta = +25C.) PARAMETER [ CONDITIONS | MIN TYP MAX | UNITS DC CHARACTERISTICS Ail R_IN open, FORCEON = GND, Supply Current, AutoShutdown Veo = 3.av| FOR FF = Vcc 1.0 10 HA Supply Current, Shutdown or 5.0V, FORCEOFF = GND 1.0 10 pA Supply Current, Ta = +25ClT EORCEON = FORCEOFF = Vcc, 04 10 mA AutoShutdown Disabled no load . , LOGIC INPUTS AND RECEIVER OUTPUTS Input Logic Threshald Low T_IN, FORCEON, FORCEOFF, EN (MAX3223) 0.8 Vv input Logic Threshold High TIN, EN, FORCEON, FORCEOFF = | Wee =38V|_ 2.0 v mput Logie mnvesnoren"'g en Vec=5.0V| 24 Input Leakage Current T_IN, EN, FORCEON, FORCEOFF +0.01 1.0 uA Output Leakage Current Receivers disabled +0.05 +10 HA Output Voltage Low lout = 1.6mA 0.4 Vv Output Voltage High flout = -4.0mA Voc -0.6 Vec-0.1 Vv AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = Vcc) Receiver Input Thresholds to Figure Positive threshald 27 v Transmitters Enabled gure Negative threshold -2.7 Receiver Input Thresholds to . | Transmitters Disabled 1pA supply current, Figure 5 0.3 0.3 INVALID Output Voltage Low lout = 1.6mA 0.4 Vv INVALID Output Voltage High lout = -1.0mA Voc - 0.6 v Receiver Threshold to : 250 Transmitters Enabled (twu) Figure pS Receiver Positive or Negative . cai 1 Ss Threshold to INVALID High (tiny) | F'gure S Receiver Positive or Negative . 30 5 Threshold to INVALID Low (tinvL) Figure S H PAAXIAA1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown ELECTRICAL CHARACTERISTICS (continued) (Voc = 3.0V to 5.5V, C104 = 0. 1pF (Note 2), Ta = TMIN to TMax, unless otherwise noted. Typical values are at Ta = +25C.) = PARAMETER CONDITIONS | MIN TYP MAX | UNITS RECEIVER INPUTS Input Voltage Range -25 25 Vv 8 Veco =3.3V| 06 1.2 Input Threshold Low Ta = +26C P Veco =5.0V| 0.8 1.5 V N . Vcc =3.3V 15 2.4 Input Threshold High Ta = +25C P 9 Voc = 5.0V 18 2.4 v > input Hysteresis 0.3 v Input Resistance Ta = +25C 3 5 7 kQ e TRANSMITTER OUTPUTS Output Voltage Swing All transmitter outputs loaded with 3kQ ta ground +5.0 5.4 Vv ) Output Resistance Vec = V+ = V- = OV, transmitter output = +2V 300 10M Q N Output Short-Circuit Current +35 +60 mA e VouT = 12V, Vcc = OV or 3.0V to 5.5V, Output Leakage Current transmitters disabled +25 pA 2 MOUSE DRIVEABILITY (MAX3243) T1IN = T2IN = GND, T3IN = Vcc, Transmitter Output Voitage T30UT loaded with 3kQ to GND, TIOUT and +5 V T2OUT loaded with 2.5mA each G TIMING CHARACTERISTICS ND Maximum Data Rate Ry = 3kQ, CL = 1000pF, one transmitter switching 120 235 kbps a . . Receiver input to receiver output. tPHL 0.3 Receiver Propagation Delay CL = 150pF PLH a4 us Receiver Output Enable Time Normal! operation 200 ns Receiver Output Disable Time Normal operation 200 ns Transmitter Skew | tPHL- tPLH | 100 500 ns Receiver Skew | PHL ~ (PLH | 200 1000 ns Voc = 3.3V, _ AL. = 3k to 7k, Ci = 200pF to 2500pF 4 8.0 30 Transition-Region Slew Rate Ta = +25C, Vius measured from +3V to -3V or -3V to +3V CL = 200pF to 1000pF 6 30 Note 2: Ci-C4 = 0. iF, tested at 3.3V 410%. C1 = 0.047uF, C2-C4 = 0.33yF, tested at 5.0V +10%. PRAXLIA 2-125MAX3221/MAX3223/MAX3243 1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown Typical Operating Characteristics (Vcc = 3.3V, 235kbps data rate, 0. 1uF capacitors, all transmitters loaded with 3kQ, Ta = +25C, unless otherwise noted.) MAX3221/MAX3223 MAX3221/MAX3223 TRANSMITTER OUTPUT VOLTAGE SLEW RATE vs. LOAD CAPACITANCE vs. LOAD CAPACITANCE 6 22 = 5 20 Sg 4 18 e 3 = 16 2 2 a i 1 S 14 & wv 12 5 0a <= oS < 10 el 2 4 E 2 a = 4 6 on = -4 4 T FOR DATAAATES UP TO 235kbps Fos 2 6 0 1000 2000 3000 4000 S000 1505001000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) MAX3243 MAX3243 TRANSMITTER OUTPUT VOLTAGE SLEW RATE vs, LOAD CAPACITANCE vs. LOAD CAPACITANCE in 24 S 2 w 5.0 Ss an 25 a & 1 TRANSMITTER AT 235kbps = 6 = 2 AT Pr 2 4 cc = 2 = 4 E 2s a iy ao = 50 8 E 6 75 4 0 1000 2000 3000 4000 5000 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF} LOAD CAPACITANCE (9F) 2-126 SUPPLY CURRENT (mA) MAX3223 SUPPLY CURRENT (mA) MAX3221/MAX3223 SUPPLY CURRENT ys. LOAD CAPACITANCE WHEN TRANSMITTING DATA 40 35 35 0 = ~ 30 5G a S 25 205 7 20 15 & uw 15 10 8 10 5 3 5 0 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) MAX2243 SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA 45 40 36 30 25 20 15 10 5 Qa 0 1000 2000 3000 = 4000 5000 LOAD CAPACITANCE (pF) MA AXISA1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown Pin Description PIN MAX3221 | MAX3223 | MAX3243 NAME FUNCTION i { _ EN Receiver Enable Control. Drive low for normal operation. Drive high to force the receiver outputs into a high-Z state. 5 5 4 C2+ Positive terminal of inverting charge-pump capacitor 6 6 2 C2- Negative terminal of inverting charge-pump capacitor 7 7 3 V- -5.5V generated by the charge pump 8 9,16 4-8 R_IN RS-232 Receiver Inputs 13 8, 17 9, 10, 11 T_OUT RS-232 Transmitter Outputs 11 12, 13 12, 13, 14 T_IN TTLICMOS Transmitter Inputs 9 10, 15 15-19 R_OUT TTLICMOS Receiver Outputs 20 R20OUTB Noninverting Receiver Outputactive in shutdown 40 4 24 TNVAUID Output of oer inp sero"! indicates if a valid RS-232 level is pres- 0 | 20 | 2 [FORCEOE | Drvelow te sat don ravers ances Power supp. Ts oer 42 14 23 FORCEON PORCEOFE set be heh) (Table) keeping transmitters on 4 4 24 C1- Negative terminal of the voltage doubler charge-pump capacitor 14 18 25 GND Ground 15 19 26 Vec +3.0V to +5.5V Supply Voltage 3 3 27 V+ +5.5V generated by the charge pump 2 2 28 Ci+ Positive terminal of the voltage doubler charge-pump capacitor Detailed Description RS-232 Transmitters Dual Charge-Pump Voltage Converter The MAX3221/MAX3223/MAX3243s 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; 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 1s a trademark of Traveling Software. The transmitters are inverting level translators that con- vert CMOS-logic levels to 5.0V EIA/TIA-232 levels. They guarantee a 120kbps data rate with worst-case loads of 3kQ in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as Laplink). Typically, the MAX3221/MAX3223/MAX3243 can oper- ate at data rates of 235kbps. Transmitters can be paral- leled to drive multiple receivers or mice (MAX3243). Figure 1 shows a complete system connection. When FORCEOFF is driven to ground, or the Auto- Shutdown circuitry senses invalid voltage levels at all receiver inputs, the transmitters are disabled and the outputs are forced into a high-impedance state. EVPCEXVW/ESCEXVAN/IECSCEXVN 2-127 MAAKUIMAMAX3221/MAX3223/MAX3243 1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown 2-128 POWER FORCEOFF MANAGEMENT UNIT OR FORCEON KEYBOARD mUATD CONTROLLER INVALID q MAXLSA MAX3243 Dp > vo cPU + CHIP <q] WITH UART RS-232 a = = Figure 1. interface Under Control of PMU 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 shut- down (FORCEOFF = low) or in AutoShutdown, the MAX3221/MAX3223's receivers are active (Table 1). Driving EN high places the receiver(s) in a high-imped- ance state. The MAX3243's receivers are high imped- ance when the part is shut down. The MAX3243 has an always-active complementary output (R2OUTB). R2OUTB is an extra output that mon- itors 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 OV in shutdown to accommodate peripherals, such as UARTs (Figure 2). . Vcc PROTECTION = DIODE f PREVIOUS Voc y RS-232 aa +! + UART 5k Tx > GND SHDN = GND L = (@) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE RECEIVER OUTPUT IN SHUTDOWN. Voc 1 m | tose Ha TRANSITION DETECTOR LL tL = 4 MAXIM - MAX3243 PROTECTION DIODE / R20UTB Veco y Rx R20UT THREE-STATED UART 5k x THIN > = GND FORCEOFF = GND L (Bb) New Max3243: IN SHUTOOWN, R2OUTB IS USED 10 MONITOR EXTERNAL DEVICES AND R2OUT IS THREE STATED, ELIMINATING A CURRENT PATH 22 THROUGH THE UART'S PROTECTION DIODE. R2IN TIQUT Figure 2. The MAX3243 detects RS-232 activity when the UART and interface are shut down. MRAXLIA1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown Table 1a. MAX3221/MAX3223 FORCEOFF and Enable Control Truth Table FORCEOFF EN T_OUT R_OUT 0 0 High-Z Active 0 1 High-Z High-Z 1 0 Active* Active 1 1 Active* High-Z TO MAX32__ 40.3V. - RIN POWER SUPPLY Tos] AND TRANSMITTERS > COUNTERL~ INVALID 03V R * TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1,A IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30s. Table 1b. MAX3243 FORCEOFF Control Truth Table FORCEOFF T_OUT R_OUT R20UTB 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. AutoShuidown A 1pA supply current is achieved with Maxim's new Auto- Shutdown 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 30us, the on-board power supply and drivers are shut off, reducing supply current to 1A. 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 assert- ed, the IC selects between these states automaticaily 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 Figure 3a. MAX32__ Entering 1A Supply Mode via AutoShutdown 42.7V: > RIN TO MAX32___ : as POWER SUPPLY > p COUNTERL- INVALID -2V R TRANSMITTERS ARE ENABLED {F; 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 30us. Figure 3b. MAX32__ with Transmitters Enabled Using AutoShutdown FORCEOFF POWER DOWN FORCEON INVALID INVALID iS AN INTERNALLY GENERATED SIGNAL THAT 1S 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. EPCEXVW/ESTEXVW/IECEXVN Figure 3c. AutoShutdown Logic MASTER SHON LINE POWER MANAGEMENT UNIT FORCEOFF FORCEON AMAAXILAA MAX3221 MAX3223 MAX3243 Figure 4, AutoShutdown with Initial Turn-On to Wake Up a Mouse or Another Syste MAAXILIA 2-129MAX3221/MAX3223/MAX3243 1p:A Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown Table 2. AutoShutdown Logic 2-130 RS-232 SIGNAL FORCEON PRESENT AT FORCEOFF INPUT INPUT INVALID OUTPUT TRANSCEIVER STATUS RECEIVER INPUT Yes H X H Normal Operation No H H L Normai Operation (Forced On) No H L L Shutdown (AutoaShutdown) Yes L xX H Shutdown (Forced Off) No L x t Shutdown (Farced Off) other systern 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 devices 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 100ps (Figure 5b). Software-Controlled Shutdown lf direct software control is desired, INVALID can be used to indicate DTR or Ring Indicator signal. Tie FORCEOFF and FORCEON together to bypass Auto- Shutdown so the line acts like a SHDN input. Applications Information Capacitor Selection The capacitor type used for C1-C4 is not critical for prop- er operation; either polarized or nonpolarized capacitors may be used. The charge pump requires 0.1pyF capaci- tors 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 capac- itor values (e.g., by a factor of 2) reduces ripple on the transmitter outputs and slightly reduces power consump- tion. 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 exces- sively 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-. TRANSMITTERS ENABLED, INVALID HIGH +2.7V | wm al > 4 5 & +0aV = gy -{ AUTOSHUTDOWN, TRANSMITTERS DISABLED, & 1A SUPPLY CURRENT, INVALID LOW m -0.V STS eT i : oe -2N TRANSMITTERS ENABLED, INVALID HIGH _ a RECEIVER INPUT VOLTAGE ) INVALID t 1 1 ! 1 i f l \ + | \ tiv, | < ee tivit I ~, | | a- wy 1 {b) 1 1 Figure 5. AutoShutdown Trip Levels MAAXLIA1p:A Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown 5V/div R 2vidiv 1 Vec = 3.3V Ci-~C4 = 0.1m F TRANSMITTER OUTPUT VOLTAGE (V) Ane owonrm = OHH KN WRN OD 0 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 0.1pF bypass capacitor is adequate. In applications that are sensitive to power- supply 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 shut- down mode. As they become active, the two transmitter outputs are shown going to opposite RS-232 levels. Each transmitter is loaded with 3kQ in parallel with 2500pF. The transmitter outputs display no ringing or undesirable tran- sients as they come out of shutdown. Note that the trans- mitters 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. Mouse Driveability (MAX3243) The MAX3243 has been specifically designed to power serial mice while operating from low-voltage power sup- plies. It has been tested with samples of ten major mouse models from six manufacturers including the leading three: Logitech (5 models), Mouse Systems, and SAAXLAA 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 i20kbps, and Figure 10 shows the same test at 240kbps. For Figure 9, all three transmitters were driv- en simultaneously at 120kbps into RS-232 loads in par- allel 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. interconnection with 3V and 5V Logic The MAX3221/MAX3223/MAX3243 can directly inter- face with various 5V logic families, including ACT and HCT CMOS. See Tabie 4 for more information on possi- ble combinations of interconnections. EPCEXVW/ECTEXUW/LECEXVINN 2-131MAX3221/MAX3223/MAX3243 1p:A Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown 33V z ap taF 26 = hey Nee a atl Pls os O-tuF 2A Tc ot O.ApF ANAXLM L 1 3 MAX324. ce [Eo 3243 -vFL a OlpF O.1pF weeT 2. e gg THIN eS iourfi9 r Loaic | . 43 [TaN T20uT fio weuts 9 ~ 12 | T3iN > T30UT 911 > Ee a 29 J R20UTB < | co 19 J RIOUT < AUN 4 oy 2 18 | R20ur < = pangs LOGIC < 8k OUTPUTS s 17 | ROUT = RINGG | as-232 < oC SP INPUTS 5k _ 18 | OUT 0 = pany? 5k 45 | RSOUT < = png i 23 5k oo FORCEON Vee 22 1 EGRCEOFF TO POWER af MANAGEMENT ~dS4f) INVALID GND UNIT E COMPUTER SERIAL PORT SERIAL MOUSE Figure 7b. Mouse Driver Test Circuit 2-132 MAAXIAA1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown Ct+ Ve 2 > : x $ He hk Tz] TI [7 C2+ MAX3221 ve TI 2. MAX3243 mr Jon > TOUT LS] pour HN LIN EN (MAX3221/3) 5 co Vcc f FORCEOFF 1000pF i} " + Table 3. Required Capacitor Values Vec ct C2, C3, C4 (V) (uF) (uF) 3.0 to 3.6 0.1 O1 4.5 to 5.5 0.047 0.33 3.0 to 5.5 0.1 0.47 Table 4. Logic Family Compatibility with Various Supply Voltages SYSTEM POWER- Vcc SUPPLY SUPPLY VOLTAGE COMPATIBILITY VOLTAGE () (V) Compatible with all CMOS 3.3 33 families. 5 5 Compatible with all TTL and CMOS-logic families. Compatible with ACT and 5 33 HCT CMOS, and with TTL. , Incompatible with AC, HC, or CD4000 CMOS. Figure 8. Loopback Test Circuit tn LE Lev TOUT i i _f| SVidiv RIOUT reo 7> [OL fT swe Voc = 3.3V. 120kbps C1-C4 = 0.1pF THN | oo ood Svidiv RIOUT TT BE OLY wntiv Qusidiv Veo = 3.3V, 235kbps Ct-C4 = 0.(pF Figure 9. Loopback Test Result at 120kbps MAXIMA Figure 10. Loopback Test Result at 235kbps 2-133 EVPEEXVW/ESCZTEXVW/IECEXVNMAX3221/MAX3223/MAX3243 1A Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown Typical Operating Circuits 3.3V ra i | 15 C5 ape tHe . = 20 cts * 3 cit V+ FT a + 63 OtuF L__4T 4. MA AXLAN TD ope 43V 5 MAX3221 > 7 > 96 eT C2+ V O.1pF ce a 6 shone =a Voc 27 O.ApF C2- at cel Ct+ Ve 1, a 11 THIN Traut 413 O1yF T_ 24 O.1uF pee Sou c* ANAXIM | oe i 9] RtouT ain [3 ce | MAXseAS Pa ~ <t O1uF TD 2B oy, Te OnE 5k Til - 3 pp N > TOUT [9 EN INVALID TO POWER Logic 43 | T2N q20uT f10,_ | RS-232 ye MMO Sm MANAGEMENT wneuts } J Pom outputs UN 12 | FORCEON FORCEOFF H16 La T30uT Jy | GND = 20 | RZOUTB a" -apieon | ~ 49 | RI0UT RINGS = 3.3V fut ac ~ cs cone 1 5k = Voc es = 2 3 4g | R20UT = RINGS Ct _ ~<a ciel . PJs 03 < omF C4] ,, AAAXIA TL olue Losi 5k 5 cme MAX3223 \ 7 OUTPUTS 17 | R30UT = pin Is RS-232 @& . oi : | P INPUTS otuF TSF oo. rE 5k apt > Trout 17 16 | R40UT = RAIN? TTYCMAS RS-232 7 INPUTS pl tan roour {8 OUTPUTS > A 23 5k 15 F R1OUT RIIN | 16 co FORCEON ca TTLICMOS 5k RS-232 "22 | apeence ~ OUTPUTS INPUTS Vet FORGEOFF __ 10] R20UT = RN] g 01 ~ ;~ TO POWER <-21] (NVALIO GND 5k MANAGEMENT UNIT Tas = RUAN TO POWER 1] EN INVALID [11s eanaGeMeNT UNIT 44] FORCEON FORCEOFF [20 cy GND p Yee is 2-134 MAAXILSA1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown 3V-Powered EIA/TIA-232 and EIA/TIA-562 Transceivers from Maxim GUAR. Supeny No. OF Recrivens | ANTEED | ElAmIA- PART TRANSMITTERS/ DATA 232 FEATURES VOLTAGE RE ACTIVE IN ) CEIVERS SHUTDOWN RATE OR 562 (kbps) MAX212 3.0 to 3.6 3/5 5 120 232 Drives mice MAX218 1.8 to 4.25 2/2 2 420 232 Operates directly from batteries without a voltage regulator MAX562 2.7 to 5.25 3/5 5 230 562 230kbps guaranteed data rate MAX563 3.0 to 3.6 2/2 2 120 562 0.1pF capacitors AutoShutdown, complementary MAX3212 2.7 03.6 3/5 5 235 232 receiver, drives mice, transient detection MAX3221 3.0 to 5.5 1A 1 120 232 0.1uF capacitors, 16-pin SSOP MAX3222 3.0 to 5.5 2/2 2 120 232 0.1pF capacitors, MAX242 pinout MAX3223 3.0 to 5.5 2/2 2 120 232 0.1pF capacitors, AutoShutdown MAX3232 3.0 to 5.5 al2 NIA 120 232 0.1pF capacitors, MAX232 pinout 0.1pF capacitors, 2 complemen- MAX3241 3.0 to 5.5 3/5 5 120 232 tary receivers, drives mice 0.1pF capacitors, AutoShutdown MAX3243 3.0 to 5.5 3/5 { 120 232 complementary receiver, drives mice MAAXKILAA 2-135 EPCEXVW/ECCEXVW/ICCEXUWNMAX3221/MAX3223/MAX3243 1pA Supply Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown Pin Configurations TOP VIEW ae ee ow aN Ly] [16] FORCEOFE cae [7] EN [| [20] FORCEOFE ots [2 5] voc c2- [3 cts [| 19] Voc E) Anareian [i] on v-3 ve [3] a} GND ci- [4] = maxze21 fia] tout Rin (4 ct-[4] pAnaxiaa [iz] Tout ca [5 /t2] FORCEON RON [5 |] AAAXIAA - cae [5] MAx3223 ig] rtin c2- [6 jit} THN rain [| MAXS248 o2- [6 15] RiOUT ve 10] INVALID naw [7 | v- 7] 14] FORCEON nin [8 [3] Riout RSW [3 Teout [3] THN Trout [8 RIN TaN ssop (a La 2 we T20UT [10] r2ouT [9] ii] VALI T30UT fi Tat fig DIP/SSOP TaN THIN [ta] SO/SSOP Chip Information MAX3221 TRANSISTOR COUNT: 269 MAX3223 TRANSISTOR COUNT: 339 MAX3243 TRANSISTOR COUNT: 476 2-136 MAAXISA