19-1289; Rev 1; 3/98 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus ____________________________Features ♦ 1µA Supply Current The MAX3225/MAX3227/MAX3245 also feature MegaBaud™ operation, guaranteeing 1Mbps for highspeed applications such as communicating with ISDN modems. The MAX3224/MAX3226/MAX3244 guarantee 250kbps operation. The transceivers have a proprietary low-dropout transmitter output stage enabling true RS232 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. The MAX3224–MAX3227 feature a logic-level output (READY) that asserts when the charge pump is regulating and the device is ready to begin transmitting. All devices are available in a space-saving SSOP package. ________________________Applications Notebook, Subnotebook, and Palmtop Computers ♦ AutoShutdown Plus—EDN Innovation of the Year ♦ Guaranteed Data Rate: 250kbps (MAX3224/3226/3244) 1Mbps (MAX3225/3227/3245) ♦ Guaranteed Slew Rate: 6V/µs (MAX3224/3226/3244) 24V/µs (MAX3225/3227/3245) ♦ Meets EIA/TIA-232 Specifications Down to 3.0V ♦ Guaranteed Mouse Driveability (MAX3244/3245) ♦ Ready-to-Transmit Logic-Level Output _______________Ordering Information TEMP. RANGE PIN-PACKAGE MAX3224CPP PART 0°C to +70°C 20 Plastic DIP MAX3224CAP MAX3224EPP MAX3224EAP 0°C to +70°C -40°C to +85°C -40°C to +85°C 20 SSOP 20 Plastic DIP 20 SSOP MAX3225CPP MAX3225CAP MAX3225EPP MAX3225EAP 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C 20 Plastic DIP 20 SSOP 20 Plastic DIP 20 SSOP Ordering Information continued at end of data sheet. Cellular Phones Battery-Powered Equipment _____________________ Selector Guide Hand-Held Equipment Peripherals PART NO. OF GUARANTEED AUTOREADY DRIVERS/ DATA RATE SHUTDOWN OUTPUT RECEIVERS (bps) PLUS Printers MAX3224 2/2 250k ✔ ✔ MAX3225 2/2 1M ✔ ✔ MAX3226 1/1 250k ✔ ✔ ✔ MAX3227 1/1 1M ✔ MAX3244 3/5 250k — ✔ MAX3245 3/5 1M — ✔ AutoShutdownPlus and MegaBaud are trademarks 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. MAX3224–MAX3227/MAX3244/MAX3245 † ________________General Description The MAX3224–MAX3227/MAX3244/MAX3245 are 3Vpowered EIA/TIA-232 and V.28/V.24 communications interfaces with automatic shutdown/wakeup features and high data-rate capabilities. All devices achieve a 1µA supply current using Maxim’s revolutionary AutoShutdown Plus™ feature. These devices automatically enter a low-power shutdown mode when the RS-232 cable is disconnected or the transmitters of the connected peripherals are inactive, and the UART driving the transmitter inputs is inactive for more than 30 seconds. They turn on again when they sense a valid transition at any transmitter or receiver input. AutoShutdown Plus saves power without changes to the existing BIOS or operating system. MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus 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, FORCEON, FORCEOFF to GND ................ -0.3V to +6V R_IN to GND ....................................................................±25V Output Voltages T_OUT to GND.............................................................±13.2V R_OUT, INVALID, READY 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 12.5mW/°C above +70°C)........... 1W 28-Pin SSOP (derate 9.52mW/°C above +70°C) .........762mW Operating Temperature Ranges MAX32_ _C_ _....................................................0°C to +70°C MAX32_ _E_ _ ..................................................-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 = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; 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 Plus FORCEON = GND, FORCEOFF = VCC, all R_IN idle, all T_IN idle 1 10 µA Supply Current, Shutdown FORCEOFF = GND 1 10 µA Supply Current, AutoShutdown Plus Disabled FORCEON = FORCEOFF = VCC, no load 0.3 1 mA 0.8 V LOGIC INPUTS AND RECEIVER OUTPUTS Input Logic Threshold Low T_IN, FORCEON, FORCEOFF Input Logic Threshold High T_IN, FORCEON, FORCEOFF VCC = 3.3V 2 VCC = 5.0V 2.4 Transmitter Input Hysteresis V 0.5 V Input Leakage Current T_IN, FORCEON, FORCEOFF ±0.01 ±1 µA Output Leakage Current R_OUT (MAX3244/MAX3245), receivers disabled ±0.05 ±10 µA Output Voltage Low IOUT = 1.6mA 0.4 V Output Voltage High IOUT = -1.0mA VCC - 0.6 VCC - 0.1 V RECEIVER INPUTS Input Voltage Range -25 Input Threshold Low TA = +25°C Input Threshold High TA = +25°C 0.6 1.2 VCC = 5.0V 0.8 1.5 1.5 2.4 VCC = 5.0V 1.8 2.4 2 0.5 TA = +25°C 3 5 _______________________________________________________________________________________ V V VCC = 3.3V Input Hysteresis Input Resistance +25 VCC = 3.3V V V 7 kΩ 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus (VCC = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS TRANSMITTER OUTPUTS Output Voltage Swing All transmitter outputs loaded with 3kΩ to ground ±5 ±5.4 Output Resistance VCC = V+ = V- = 0, transmitter outputs = ±2V 300 10M Output Short-Circuit Current VCC = 0 or 3V to 5.5V, VOUT = ±12V, Transmitters disabled Output Leakage Current V Ω ±60 mA ±25 µA MOUSE DRIVEABILITY (MAX3244/MAX3245) T1IN = T2IN = GND, T3IN = VCC, T3OUT loaded with 3kΩ to GND, T1OUT and T2OUT loaded with 2.5mA each AUTOSHUTDOWN PLUS (FORCEON = GND, FORCEOFF = VCC) Transmitter Output Voltage Receiver Input Threshold to INVALID Output High Figure 4a Receiver Input Threshold to INVALID Output Low Figure 4a INVALID, READY (MAX3224–MAX3227) Output Voltage Low IOUT = -1.6mA INVALID, READY (MAX3224–MAX3227) Output Voltage High IOUT = -1.0mA ±5 V Positive threshold Negative threshold 2.7 -2.7 -0.3 V 0.3 V 0.4 V VCC - 0.6 V Receiver Positive or Negative Threshold to INVALID High tINVH VCC = 5V, Figure 4b 1 µs Receiver Positive or Negative Threshold to INVALID Low tINVL VCC = 5V, Figure 4b 30 µs Receiver or Transmitter Edge to Transmitters Enabled tWU VCC = 5V, Figure 5b (Note 2) 100 µs Receiver or Transmitter Edge to tAUTOSHDN VCC = 5V, Figure 5b (Note 2) Transmitters Shutdown 15 30 60 sec _______________________________________________________________________________________ 3 MAX3224–MAX3227/MAX3244/MAX3245 ELECTRICAL CHARACTERISTICS (continued) MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus TIMING CHARACTERISTICS—MAX3224/MAX3226/MAX3244 (VCC = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL Maximum Data Rate Receiver Propagation Delay CONDITIONS MIN RL = 3kΩ, CL = 1000pF, one transmitter switching tPHL tPLH TYP MAX 250 kbps 0.15 R_IN to R_OUT, CL = 150pF UNITS µs 0.15 Receiver Output Enable Time Normal operation (MAX3244 only) 200 ns Receiver Output Disable Time Normal operation (MAX3244 only) 200 ns (Note 3) 100 ns 50 ns Transmitter Skew tPHL - tPLH Receiver Skew tPHL - tPLH VCC = 3.3V, TA = +25°C, RL = 3kΩ to 7kΩ, measured from +3V to -3V or -3V to +3V Transition-Region Slew Rate CL = 150pF to 1000pF 6 30 CL = 150pF to 2500pF 4 30 V/µs TIMING CHARACTERISTICS—MAX3225/MAX3227/MAX3245 (VCC = +3V to +5.5V, C1–C4 = 0.1µF, tested at 3.3V ±10%; CL = 0.047µF, C2–C4 = 0.33µF, tested at 5.0V ±10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL Maximum Data Rate Receiver Propagation Delay tPHL tPLH CONDITIONS MIN RL = 3kΩ, CL = 1000pF, one transmitter switching 250 VCC = 3.0V to 4.5V, RL = 3kΩ, CL = 250pF, one transmitter switching 1000 VCC = 4.5V to 5.5V, RL = 3kΩ, CL = 1000pF, one transmitter switching 1000 TYP MAX kbps 0.15 R_IN to R_OUT, CL = 150pF UNITS µs 0.15 Receiver Output Enable Time Normal operation (MAX3245 only) 200 ns Receiver Output Disable Time Normal operation (MAX3245 only) 200 ns (Note 3) 25 ns 50 ns Transmitter Skew tPHL - tPLH Receiver Skew tPHL - tPLH Transition-Region Slew Rate VCC = 3.3V, TA = +25°C, RL = 3kΩ to 7kΩ, CL = 150pF to 1000pF, measured from +3V to -3V or -3V to +3V 24 Note 2: A transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic thresholds. Note 3: Transmitter skew is measured at the transmitter zero cross points. 4 _______________________________________________________________________________________ 150 V/µs 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus +SLEW 8 6 VOUT3000 4000 5000 10 1000 2000 3000 4000 0 5000 MAX3225/MAX3227 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE 60 80 -SLEW 50 +SLEW 40 30 1 TRANSMITTER AT 1Mbps 1 TRANSMITTER AT 62.5kbps (MAX3225) 1000 1500 2000 2500 0 500 MAX3225/MAX3227 TRANSMITTER SKEW vs. LOAD CAPACITANCE 20 AVERAGE; 10 PARTS 15 20 1000 1500 2000 LOAD CAPACITANCE (pF) 2500 3000 1000 1500 MAX3224-06 2000 MAX3224–MAX3227 READY TURN-OFF TIME vs. TEMPERATURE 200 MAX3224-08 26 0 500 MAX3224–MAX3227 READY TURN-ON TIME vs. TEMPERATURE 28 22 0 LOAD CAPACITANCE (pF) 30 5 1Mbps 0 32 24 30 2500 34 10 500 2000 180 READY TURN-OFF TIME (ns) 25 1500 36 READY TURN-ON TIME (µs) 30 1000 38 MAX3224-07 1 TRANSMITTER AT 512kbps 1 TRANSMITTER AT 30kbps (MAX3225) LOAD = 3kΩ + CL 1.5Mbps 40 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) 50 50 10 0 500 2Mbps 60 20 10 -7.5 70 2500 MAX3224-09 1Mbps 1 TRANSMITTER AT FULL DATA RATE 1 TRANSMITTER AT 1/16 DATA RATE (MAX3225) LOAD = 3kΩ + CL 90 SUPPLY CURRENT (mA) 70 5000 100 MAX3224-05 MAX3224-04 80 -5.0 0 4000 MAX3225/MAX3227 SLEW RATE vs. LOAD CAPACITANCE 20 35 3000 MAX3225/MAX3227 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 1 TRANSMITTER AT FULL DATA RATE 1 TRANSMITTER AT 1/16 DATA RATE (MAX3225) LOAD = 3kΩ + CL 1.5Mbps 1Mbps 2Mbps 40 2000 LOAD CAPACITANCE (pF) 1.5Mbps 45 1000 LOAD CAPACITANCE (pF) 2.5 0 T1 TRANSMITTING AT 250kbps T2 (MAX3224) TRANSMITTING AT 15.6kbps 5 0 0 2Mbps -2.5 20kbps 15 LOAD CAPACITANCE (pF) 5.0 0 MAX3224-03 20 0 2000 120kbps 25 2 7.5 TRANSMITTER SKEW (ns) 30 FOR DATA RATES UP TO 250kbps 1000 250kbps 35 4 0 TRANSMITTER OUTPUT VOLTAGE (V) -SLEW 10 40 SUPPLY CURRENT (mA) SLEW RATE (V/µs) 0 -1 -2 -3 -4 -5 -6 14 12 T1 TRANSMITTING AT 250kbps T2 (MAX3224) TRANSMITTING AT 15.6kbps 45 MAX3224-02 VOUT+ 4 3 2 1 16 MAX3224-01 6 5 MAX3224/MAX3226 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE MAX3224/MAX3226 SLEW RATE vs. LOAD CAPACITANCE SLEW RATE (V/µs) TRANSMITTER OUTPUT VOLTAGE (V) MAX3224/MAX3226 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 160 140 120 100 80 60 40 20 0 -40 -20 0 20 40 60 TEMPERATURE (°C) 80 100 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) _______________________________________________________________________________________ 5 MAX3224–MAX3227/MAX3244/MAX3245 __________________________________________Typical Operating Characteristics (VCC = +3.3V, 250kbps data rate, C1–C4 = 0.1µF, all transmitters loaded with 3kΩ and CL, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = +3.3V, 250kbps data rate, C1–C4 = 0.1µF, all transmitters loaded with 3kΩ and CL, TA = +25°C, unless otherwise noted.) 10 8 6 4 1000 2000 3000 4000 0 1000 2000 3000 4000 60 SLEW RATE (V/µs) 1Mbps 1 TRANSMITTER AT FULL DATA RATE 2 TRANSMITTERS AT 1/16 DATA RATE 2Mbps 1.5Mbps 1Mbps 4000 50 40 30 20 -5.0 10 -7.5 1 TRANSMITTER AT 1Mbps 2 TRANSMITTERS AT 62.5kbps 0 400 800 1200 1600 2000 0 400 800 1200 1600 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) MAX3245 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE MAX3245 TRANSMITTER SKEW vs. LOAD CAPACITANCE 50 MAX3224-15 100 90 45 80 2000 MAX3224-16 0 40 70 2Mbps 60 1.5Mbps 50 40 30 1Mbps TRANSMITTER SKEW (ns) SUPPLY CURRENT (mA) 3000 MAX3224-14 MAX3224-13 TRANSMITTER OUTPUT VOLTAGE (V) 70 2Mbps 1.5Mbps 2000 MAX3245 SLEW RATE vs. LOAD CAPACITANCE 5.0 2.5 1000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) 7.5 -2.5 0 5000 MAX3245 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 35 30 25 20 15 10 20 1 TRANSMITTER AT FULL DATA RATE 2 TRANSMITTERS AT 1/16 DATA RATE 10 5 0 0 0 400 800 1200 1600 LOAD CAPACITANCE (pF) 6 20kbps 20 0 5000 LOAD CAPACITANCE (pF) 0 120kbps 30 0 0 250kbps 40 10 2 VOUT- 1 TRANSMITTER AT 250kbps 2 TRANSMITTERS AT 15.6kbps 50 SUPPLY CURRENT (mA) 1 0 -1 -2 -3 -4 -5 -6 12 SLEW RATE (V/µs) 1 TRANSMITTER AT 250kbps 2 TRANSMITTERS AT 15.6kbps 60 MAX3224-11 VOUT+ 4 3 2 14 MAX3224-10 6 5 MAX3244 OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE MAX3244 SLEW RATE vs. LOAD CAPACITANCE MAX3224-12 MAX3244 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE TRANSMITTER OUTPUT VOLTAGE (V) MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus 2000 0 1000 2000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 3000 5000 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus PIN MAX3224 MAX3225 MAX3226 MAX3227 MAX3244 MAX3245 NAME FUNCTION 1 1 — READY 2 2 28 C1+ 3 3 27 V+ +5.5V generated by the charge pump 4 4 24 C1- Negative Terminal of 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, 17 13 9–11 T_OUT 9, 16 8 4–8 R_IN 10, 15 9 15–19 R_OUT 11 10 21 INVALID 12, 13 11 12–14 T_IN 14 12 23 FORCEON 18 14 25 GND Ground 19 15 26 VCC +3.0V to +5.5V Single Supply Voltage 20 16 22 FORCEOFF — — 20 R2OUTB Ready to Transmit Output, active high. READY is enabled high when V- goes below -4V and the device is ready to transmit. Positive Terminal of Voltage-Doubler Charge-Pump Capacitor -5.5V generated by the charge pump RS-232 Transmitter Outputs RS-232 Receiver Inputs TTL/CMOS Receiver Outputs Valid Signal Detector Output, active low. A logic high indicates that a valid RS-232 level is present on a receiver input. TTL/CMOS Transmitter Inputs Force-On Input, active high. Drive high to override AutoShutdown Plus, keeping transmitters and receivers on (FORCEOFF must be high) (Table 1). Force-Off Input, active low. Drive low to shut down transmitters, receivers (except R2OUTB), and charge pump. This overrides AutoShutdown Plus and FORCEON (Table 1). TTL/CMOS Noninverting Complementary Receiver Outputs. Always active. _______________Detailed Description Dual Charge-Pump Voltage Converter The READY output (MAX3224–MAX3227) is low when the charge pumps are disabled in shutdown mode. The READY signal asserts high when V- goes below -4V. The MAX3224–MAX3227/MAX3244/MAX3245’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 range. The charge pump operates in discontinuous mode: if the output voltages are less than 5.5V, the charge pump is enabled; if the output voltages exceed 5.5V, the charge-pump is disabled. Each charge pump requires a flying capacitor (C1, C2) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies. The transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The MAX3224/MAX3226/MAX3244 guarantee a 250kbps data rate (1Mbps for the MAX3225/MAX3227/ MAX3245) 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. Figure 1 shows a complete system connection. RS-232 Transmitters LapLink is a trademark of Traveling Software. _______________________________________________________________________________________ 7 MAX3224–MAX3227/MAX3244/MAX3245 Pin Description MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER FORCEOFF VCC FORCEON INVALID PROTECTION DIODE MAX3244 MAX3245 PREVIOUS RS-232 VCC I Rx 5k UART Tx CPU GND I/O CHIP WITH UART 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 When FORCEOFF is driven to ground or when the AutoShutdown Plus circuitry senses that all receiver and transmitter inputs are inactive for more than 30sec, the transmitters are disabled and the outputs go into a highimpedance state. When powered off or shut down, the outputs can be driven to ±12V. The transmitter inputs do not have pull-up resistors. Connect unused inputs to GND or VCC. R2OUTB VCC Rx 5k Tx GND b) R2IN R2OUT THREE-STATED UART RS-232 Receivers The receivers convert RS-232 signals to CMOS-logic output levels. The MAX3224–MAX3227 feature inverting outputs that always remain active (Table 1). The MAX3244/MAX3245 have inverting three-state outputs that are high impedance when shut down (FORCEOFF = GND) (Table 1). MAX3244 MAX3245 T1IN T1OUT FORCEOFF = GND NEW MAX3244/MAX3245: 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 MAX3244/MAX3245 detect RS-232 activity when the UART and interface are shut down. 8 _______________________________________________________________________________________ 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus RECEIVER OR TRANSMITTER EDGE WITHIN 30sec T_OUT R_OUT (MAX3224/ MAX3225/ MAX3226/ MAX3227) R_OUT (MAX3244/ MAX3245) R2OUTB (MAX3244/ MAX3245) FORCEON FORCEOFF VALID RECEIVER LEVEL Shutdown (Forced Off) X 0 X X High-Z Active High-Z Active Normal Operation (Forced On) 1 1 X X Active Active Active Active Normal Operation (AutoShutdown Plus) 0 1 X Yes Active Active Active Active Shutdown (AutoShutdown Plus) 0 1 X No High-Z Active Active Active Normal Operation INVALID* 1 Yes X Active Active Active Active Normal Operation INVALID* 1 X Yes Active Active Active Active Shutdown INVALID* 1 No No High-Z Active Active Active Normal Operation (AutoShutdown) INVALID* INVALID** Yes X Active Active Active Active Shutdown (AutoShutdown) INVALID* INVALID** No X High-Z Active High-Z Active OPERATION STATUS X = Don’t care * INVALID connected to FORCEON ** INVALID connected to FORCEON and FORCEOFF The MAX3244/MAX3245 feature an extra, always active, noninverting output, R2OUTB. R2OUTB output monitors receiver activity while the other receivers are high impedance, allowing Ring Indicator applications to be monitored without forward biasing other devices connected to the receiver outputs. This is ideal for systems where V CC is set to ground in shutdown to accommodate peripherals such as UARTs (Figure 2). The MAX3224–MAX3227/MAX3244/MAX3245 feature an INVALID output that is enabled low when no valid RS-232 voltage levels have been detected on all receiver inputs. Because INVALID indicates the receiver input’s condition, it is independent of FORCEON and FORCEOFF states (Figures 3 and 4). AutoShutdown Plus Mode The MAX3224–MAX3227/MAX3244/MAX3245 achieve a 1µA supply current with Maxim’s AutoShutdown Plusfeature, which operates when FORCEOFF is high and a FORCEON is low. When these devices do not sense a valid signal transition on any receiver and transmitter input for 30sec, the on-board charge pumps are shut down, reducing supply current to 1µA. This occurs if the RS-232 cable is disconnected or if the connected peripheral transmitters are turned off, and the UART driving the transmitter inputs is inactive. The system turns on again when a valid transition is applied to any RS-232 receiver or transmitter input. As a result, the system saves power without changes to the existing BIOS or operating system. _______________________________________________________________________________________ 9 MAX3224–MAX3227/MAX3244/MAX3245 Table 1. Output Control Truth Table +0.3V T_IN R_IN 30µs TIMER R -0.3V INVALID R_IN EDGE DETECT Figure 3a. INVALID Functional Diagram, INVALID Low FORCEOFF S 30sec TIMER EDGE DETECT INVALID ASSERTED IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30µs. AUTOSHDN R FORCEON Figure 3c. AutoShutdown Plus Logic +2.7V FORCEOFF POWERDOWN* FORCEON R_IN 30µs TIMER R -2.7V AUTOSHDN INVALID INVALID DEASSERTED IF ANY RECEIVER INPUT HAS BEEN BETWEEN +2.7V AND -2.7V FOR LESS THAN 30µs. Figure 3b. INVALID Functional Diagram, INVALID High * POWERDOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES. Figure 3d. Power-Down Logic Table 2. INVALID Truth Table INVALID HIGH RS-232 SIGNAL PRESENT AT ANY RECEIVER INPUT INVALID OUTPUT Yes High No Low Figures 3a and 3b depict valid and invalid RS-232 receiver voltage levels. INVALID indicates the receiver input’s condition, and is independent of FORCEON and FORCEOFF states. Figure 3 and Tables 1 and 2 summarize the operating modes of the MAX3224– MAX3227/MAX3244/MAX3245 devices. FORCEON and FORCEOFF override AutoShutdown Plus circuitry. When neither control is asserted, the IC selects between these states automatically based on the last receiver or transmitter input edge received. When shut down, the device’s charge pumps turn off, V+ is pulled to VCC, V- is pulled to ground, the transmitter outputs are high impedance, and READY (MAX3224–MAX3227) is driven low. The time required to exit shutdown is typically 100µs (Figure 8). 10 +2.7V RECEIVER INPUT LEVELS MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus INDETERMINATE +0.3V 0 INVALID LOW -0.3V INDETERMINATE -2.7V INVALID HIGH Figure 4a. Receiver Positive/Negative Thresholds for INVALID By connecting FORCEON to INVALID, the MAX3224– MAX3227/MAX3244/MAX3245 shut down when no valid receiver level and no receiver or transmitter edge is detected for 30sec, and wake up when a valid receiver level or receiver or transmitter edge is detected. By connecting FORCEON and FORCEOFF to INVALID, the MAX3224–MAX3227/MAX3244/MAX3245 shutdown when no valid receiver level is detected and wake up ______________________________________________________________________________________ 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus INVALID } REGION TRANSMITTER INPUTS TRANSMITTER OUTPUTS INVALID OUTPUT VCC tINVL tINVH 0 tAUTOSHDN tAUTOSHDN tWU tWU *VCC OUTPUT 0 V+ VCC 0 V- *MAX3224–MAX3227 Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram POWERMANAGEMENT UNIT MASTER SHDN LINE 0.1µF 1M FORCEOFF FORCEON MAX3224 MAX3225 MAX3226 MAX3227 MAX3244 MAX3245 Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a Mouse or Another System when a valid receiver level is detected (same functionality as AutoShutdown feature on MAX3221/MAX3223/ MAX3243). A mouse or other system with AutoShutdown Plus may need time to wake up. Figure 5 shows a circuit that forces the transmitters on for 100ms, allowing enough time for the other system to realize that the MAX3244/ MAX3245 is awake. If the other system outputs valid RS-232 signal transitions within that time, the RS-232 ports on both systems remain enabled. Software-Controlled Shutdown If direct software control is desired, use INVALID to indicate DTR or Ring Indicator signal. Tie FORCEOFF and FORCEON together to bypass the AutoShutdown Plus so the line acts like a SHDN input. ______________________________________________________________________________________ 11 MAX3224–MAX3227/MAX3244/MAX3245 RECEIVER INPUTS MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus __________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 0.1µF capacitors for 3.3V operation. For other supply voltages, see 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, C4, and CBYPASS, 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), which usually rises at low temperatures, 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 charge-pump capacitor C1. Connect bypass capacitors as close to the IC as possible. High Data Rates The MAX3224/MAX3226/MAX3244 maintain the RS-232 ±5.0V minimum transmitter output voltage even at high data rates. Figure 7 shows a transmitter loopback test circuit. Figure 8 shows a loopback test result at 120kbps, and Figure 9 shows the same test at 250kbps. For Figure 8, all transmitters were driven FORCEON = FORCEOFF 5V/div 0 T1OUT 2V/div 0 Figure 6. Transmitter Outputs when Exiting Shutdown or Powering Up VCC CBYPASS C1, CBYPASS (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 0.22 1 VCC C1+ V+ C3* C1 C1C2+ C2 C2- MAX3224 MAX3225 MAX3226 MAX3227 MAX3244 MAX3245 5k FORCEON FORCEOFF C4 R_ IN R_ OUT VCC V- T_ OUT T_ IN Table 3. Required Minimum Capacitance Values VCC (V) READY 5µs/div 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 (one transmitter input 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. Note that the transmitters are enabled only when the magnitude of V- exceeds approximately -3V. T2OUT VCC = 3.3V C1–C4 = 0.1µF 5V/div 0 GND *C3 CAN BE RETURNED TO VCC OR GND. Figure 7. Loopback Test Circuit 12 ______________________________________________________________________________________ 1000pF 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus T1IN Mouse Driveability The MAX3244/MAX3245 are specifically designed to power serial mice while operating from low-voltage power supplies. They have been tested with leading mouse brands from manufacturers such as Microsoft and Logitech. The MAX3244/MAX3245 successfully drove all serial mice tested and met their respective current and voltage requirements. The MAX3244/ MAX3245 dual charge pump ensures the transmitters will supply at least ±5V during worst-case conditions. Figure 11a shows the transmitter output voltages under increasing load current. Figure 11b shows a typical mouse connection. 5V/div T1IN 5V/div 5V/div T1OUT 5V/div 5V/div R1OUT T1OUT R1OUT 5V/div VCC = 3.3V VCC = 3.3V 200ns/div 2µs/div 5V/div T1IN 5V/div T1OUT 5V/div R1OUT VCC = 3.3V 2µs/div Figure 9. MAX3224/MAX3226/MAX3244 Loopback Test Result at 250kbps Figure 10. MAX3225/MAX3227/MAX3245 Loopback Test Result at 1Mbps TRANSMITTER OUTPUT VOLTAGE (V) Figure 8. MAX3224/MAX3226/MAX3244 Loopback Test Result at 120kbps 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 VOUT+ VCC = 3.0V VOUT+ VCC VOUTVOUT- 0 1 2 3 4 5 6 7 8 9 10 LOAD CURRENT PER TRANSMITTER (mA) Figure 11a. MAX324_ Transmitter Output Voltage vs. Load Current per Transmitter ______________________________________________________________________________________ 13 MAX3224–MAX3227/MAX3244/MAX3245 simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 9, a single transmitter was driven at 250kbps, and all transmitters were loaded with an RS-232 receiver in parallel with 250pF. The MAX3225/MAX3227/MAX3245 maintain the RS-232 ±5.0V minimum transmitter output voltage at data rates up to 1Mbps (MegaBaud). Figure 10 shows a loopback test result with a single transmitter driven at 1Mbps and all transmitters loaded with an RS-232 receiver in parallel with 250pF. MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus +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+ MAX3244 MAX3245 COMPUTER SERIAL PORT 3 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 POWERMANAGEMENT UNIT 22 21 R5OUT SERIAL MOUSE 5k FORCEON FORCEOFF INVALID GND 25 Figure 11b. Mouse Driver Test Circuit 14 ______________________________________________________________________________________ 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus Table 4. Logic Family Compatibility with Various Supply Voltages SYSTEM POWER-SUPPLY VOLTAGE (V) VCC SUPPLY VOLTAGE (V) 3.3 3.3 5 5 5 3.3 COMPATIBILITY Compatible with all CMOS families Compatible with all TTL and CMOS families Compatible with ACT and HCT CMOS, and with AC, HC, or CD4000 CMOS Table 5. 3.0V to 5.5V Powered RS-232 Transceivers from Maxim PART SUPPLY VOLTAGE RANGE (V) NO. OF Tx/Rx SUPPLY CURRENT (µA) AUTOSHUTDOWN PLUS AUTOSHUTDOWN GUARANTEED DATA RATE (bps) MAX3241 +3.0 to +5.5 3/5 300 — — 120k MAX3243 +3.0 to +5.5 3/5 1 — Yes 120k MAX3244 +3.0 to +5.5 3/5 1 Yes — 250k MAX3245 +3.0 to +5.5 3/5 1 Yes — 1M MAX3232 +3.0 to +5.5 2/2 300 — — 120k MAX3222 +3.0 to +5.5 2/2 300 — — 120k MAX3223 +3.0 to +5.5 2/2 1 — Yes 120k MAX3224 +3.0 to +5.5 2/2 1 Yes — 250k MAX3225 +3.0 to +5.5 2/2 1 Yes — 1M MAX3221 +3.0 to +5.5 1/1 1 — Yes 120k MAX3226 +3.0 to +5.5 1/1 1 Yes — 250k MAX3227 +3.0 to +5.5 1/1 1 Yes — 1M ______________________________________________________________________________________ 15 MAX3224–MAX3227/MAX3244/MAX3245 Interconnection with 3V and 5V Logic The MAX3224–MAX3227/MAX3244/MAX3245 can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 4 for more information on possible combinations of interconnections. Table 5 lists other Maxim 3.0V to 5.5V powered transceivers. MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus ___________________________________________________Typical Operating Circuits +3.3V +3.3V 15 0.1µF CBYPASS 2 C1+ C1 0.1µF 4 C15 C2 0.1µF 6 C2+ 3 V+ MAX3226 MAX3227 V- 9 R1OUT C3 0.1µF C1 0.1µF C4 0.1µF C2 0.1µF 7 C2- 11 T1IN 12 27 V+ C3 0.1µF 24 C11 2 C2+ MAX3244 MAX3245 V- 3 C4 0.1µF C2- 14 T1IN T1OUT 9 R1IN 8 13 T2IN T2OUT 10 12 T3IN T3OUT 11 AUTOSHUTDOWN INVALID 10 PLUS FORCEOFF 16 FORCEON 28 C1+ VCC T1OUT 13 5k 1 READY 26 CBYPASS 0.1µF VCC GND TO POWERMANAGEMENT UNIT VCC 22 FORCEOFF 23 FORCEON AUTOSHUTDOWN PLUS INVALID 21 20 R2OUTB 14 19 R1OUT R1IN 4 +3.3V CBYPASS C1 0.1µF 2 C1+ 4 5 C2 0.1µF 6 C1C2+ VCC MAX3224 MAX3225 V- C3 0.1µF R3IN 6 C4 0.1µF 5k 16 R4OUT T1OUT 17 R4IN 7 5k RS-232 OUTPUTS T2OUT 8 15 R5OUT R5IN 8 5k R1IN 16 15 R1OUT TTL/CMOS OUTPUTS RS-232 INPUTS 5k R2IN 10 R2OUT 9 GND 25 5k 1 READY 14 AUTOSHUTDOWN PLUS INVALID 11 FORCEOFF 20 FORCEON GND TO POWERMANAGEMENT UNIT VCC 18 16 5 5k 17 R3OUT 7 C2- 12 T2IN R2IN 18 R2OUT 3 V+ 13 T1IN TTL/CMOS INPUTS 5k 19 0.1µF ______________________________________________________________________________________ 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus READY 1 C1+ 2 V+ 3 C1- 4 C2+ 5 MAX3226 MAX3227 C2- 6 V- 7 R1IN 8 16 FORCEOFF C2+ 1 28 C1+ 15 VCC C2- 2 27 V+ 14 GND V- 3 26 VCC 13 T1OUT R1IN 4 25 GND 12 FORCEON R2IN 5 R3IN 6 10 INVALID R4IN 7 22 FORCEOFF 9 R1OUT 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 20 FORCEOFF C1+ 2 19 VCC V+ 3 18 GND C1- 4 C2+ 5 23 FORCEON 17 T1OUT MAX3224 MAX3225 C2- 6 SO/SSOP 16 R1IN 15 R1OUT V- 7 T2OUT 24 C1- 11 T1IN SSOP READY 1 MAX3244 MAX3245 14 FORCEON 8 13 T1IN R2IN 9 12 T2IN R2OUT 10 11 INVALID DIP/SSOP __Ordering Information (continued) ___________________Chip Information PIN-PACKAGE MAX3224 MAX3226CAE 0°C to +70°C 16 SSOP TRANSISTOR COUNT: 1129 MAX3226EAE -40°C to +85°C 16 SSOP MAX3225 MAX3227CAE 0°C to +70°C 16 SSOP TRANSISTOR COUNT: 1129 MAX3227EAE MAX3244CWI MAX3244CAI -40°C to +85°C 0°C to +70°C 0°C to +70°C 16 SSOP 28 Wide SO 28 SSOP MAX3244EWI MAX3244EAI MAX3245CWI MAX3245CAI -40°C to +85°C -40°C to +85°C 0°C to +70°C 0°C to +70°C 28 Wide SO 28 SSOP 28 Wide SO 28 SSOP MAX3245EWI MAX3245EAI -40°C to +85°C -40°C to +85°C 28 Wide SO 28 SSOP PART TEMP. RANGE MAX3226 TRANSISTOR COUNT: 1129 MAX3227 TRANSISTOR COUNT: 1129 MAX3244/MAX3245 TRANSISTOR COUNT: 1335 ______________________________________________________________________________________ 17 MAX3224–MAX3227/MAX3244/MAX3245 ___________________________________________________________ Pin Configurations ________________________________________________________Package Information SSOP.EPS MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus 18 ______________________________________________________________________________________ 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus SOICW.EPS ______________________________________________________________________________________ 19 MAX3224–MAX3227/MAX3244/MAX3245 ___________________________________________Package Information (continued) ___________________________________________Package Information (continued) PDIPN.EPS MAX3224–MAX3227/MAX3244/MAX3245 1µA Supply Current, 1Mbps, 3.0V to 5.5V, RS-232 Transceivers with AutoShutdown Plus 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. 20 ____________________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.