19-1473; Rev 2; 8/04 ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors ____________________________Features The MAX3233E/MAX3235E are EIA/TIA-232 and V.28/V.24 communications interfaces with automatic shutdown/ wake-up features, high data-rate capabilities, and enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to ±15kV using IEC 1000-4-2 Air-Gap Discharge, to ±8kV using IEC 1000-4-2 Contact Discharge, and to ±15kV using the Human Body Model. The MAX3233E operates from a +3.3V supply; the MAX3235E operates from +5.0V. 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 following two conditions occur: either 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. ♦ ESD Protection for RS-232 I/O Pins ±15kV—Human Body Model ±8kV—IEC 1000-4-2, Contact Discharge ±15kV—IEC 1000-4-2, Air-Gap Discharge ♦ Latchup Free ♦ 1µA Supply Current ♦ AutoShutdown Plus—1997 EDN Magazine Innovation of the Year ♦ Single-Supply Operation +3.0V to +3.6V (MAX3233E) +4.5V to +5.5V (MAX3235E) ♦ 250kbps Guaranteed Data Rate ♦ 6V/µs Guaranteed Slew Rate ♦ Meets EIA/TIA-232 Specifications Down to 3.0V (MAX3233E) ♦ Internal Charge-Pump Capacitors The MAX3233E/MAX3235E have internal dual charge pumps requiring no external capacitors. Both transceivers have a proprietary low-dropout transmitter output stage that enables true RS-232 performance from a +3.0V to +3.6V supply for the MAX3233E or a +4.5V to +5.5V supply for the MAX3235E. These devices are guaranteed to operate up to 250kbps. Both are available in space-saving 20-pin wide SO or plastic DIP packages. ________________________Applications Subnotebook and Palmtop Computers Cellular Phones Battery-Powered Equipment Handheld Equipment Peripherals Embedded Systems _______________Ordering Information Pin Configuration/ Functional Diagram R2OUT INVALID T2IN T1IN FORCEON R1OUT T1OUT R1IN PART TEMP RANGE PIN-PACKAGE MAX3233ECWP 0°C to +70°C 20 SO MAX3233ECPP 0°C to +70°C 20 Plastic DIP MAX3233EEWP -40°C to +85°C 20 SO MAX3233EEPP -40°C to +85°C 20 Plastic DIP Ordering Information continued at end of data sheet. AutoShutdown Plus is a trademark of Maxim Integrated Products, Inc. VCC FORCEOFF 1 2 20 MAX3233E MAX3235E 19 3 18 4 17 5 16 6 CHARGE PUMP 15 7 14 8 13 9 12 10 11 R2IN T2OUT GND VC2C2+ C1C1+ V+ V+ SO/DIP †Co7; 4,7er pg. Typical Operating Circuit appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX3233E/MAX3235E † ________________General Description MAX3233E/MAX3235E ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors ABSOLUTE MAXIMUM RATINGS VCC to GND (MAX3233E).........................................-0.3V to +4V VCC to GND (MAX3235E).........................................-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 to GND ......................-0.3V to (VCC + 0.3V) Short-Circuit Duration T_OUT to GND ......................................................Continuous Continuous Power Dissipation (TA = +70°C) Wide SO (derate 10mW/°C above +70°C)..................800mW Plastic DIP (derate 11.11mW/°C above +70°C) .........889mW Operating Temperature Ranges MAX323_EC_P ...................................................0°C to +70°C MAX323_EE_P ................................................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) (Note 2) ...................+300°C Note 1: V+ and V- can have maximum magnitudes of 7V, but their absolute difference cannot exceed 13V. Note 2: Maximum reflow temperature is +220°C. Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VCC = +3.0V to +3.6V for MAX3233E, VCC = +4.5V to +5.5V for MAX3235E; 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 for MAX3233E, VCC = 5.0V for MAX3235E, 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, MAX3233E 2 VCC = 5.0V, MAX3235E 2.4 Transmitter Input Hysteresis V 0.5 Input Leakage Current T_IN, FORCEON, FORCEOFF Output Voltage Low IOUT = 1.6mA Output Voltage High IOUT = -1.0mA ±0.01 V ±1 µA 0.4 V 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 1.0 VCC = 5.0V, MAX3235E 0.8 1.3 1.5 2.4 VCC = 5.0V, MAX3235E 1.8 2.4 2 0.5 TA = +25°C 3 5 _______________________________________________________________________________________ V V VCC = 3.3V, MAX3233E Input Hysteresis Input Resistance +25 VCC = 3.3V, MAX3233E V V 7 kΩ ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors (VCC = +3.0V to +3.6V for MAX3233E, VCC = +4.5V to +5.5V for MAX3235E; 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 V Output Resistance VCC = V+ = V- = 0, transmitter outputs = ±2V 300 10M Ω Output Short-Circuit Current ±60 VOUT = ± 12V transmitters disabled Output Leakage Current VCC = 0 or +3.0V to 3.6V (MAX3233E) ±25 VCC = 0 or +4.5V to 5.5V (MAX3235E) ±25 mA µA ESD PROTECTION R_IN, T_OUT IEC1000-4-2 Air Discharge ±15 IEC1000-4-2 Contact Discharge ±8 Human Body Model ±15 kV AutoShutdown PLUS (FORCEON = GND, FORCEOFF = VCC) Receiver Input Threshold to INVALID Output High Figure 3a Receiver Input Threshold to INVALID Output Low Figure 3a INVALID Output Voltage Low IOUT = -1.6mA INVALID, Output Voltage High IOUT = -1.0mA Receiver Positive or Negative Threshold to INVALID High tINVH Figure 3b Receiver Positive or Negative Threshold to INVALID Low tINVL Figure 3b Receiver or Transmitter Edge to Transmitters Enabled tWU Figure 3b (Note 3) Receiver or Transmitter Edge to tAUTOSHDN Figure 3b (Note 3) Transmitters Shut Down Positive threshold Negative threshold 2.7 -2.7 -0.3 0.3 V 0.4 V VCC - 0.6 V 1 MAX3233E 70 MAX3235E 50 µs µs 100 15 V 30 µs 60 s Note 3: A transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic thresholds. _______________________________________________________________________________________ 3 MAX3233E/MAX3235E ELECTRICAL CHARACTERISTICS (continued) TIMING CHARACTERISTICS (VCC = +3.0V to +3.6V for MAX3233E, VCC = +4.5V to +5.5V for MAX3235E; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN RL = 3kΩ, CL = 1000pF, one transmitter switching Maximum Data Rate tPHL R_IN to R_OUT, CL = 150pF Receiver Propagation Delay tPLH TYP MAX UNITS 250 kbps MAX3233E 70 MAX3235E 100 MAX3233E 250 MAX3235E 150 ns Receiver Output Enable Time Normal operation 200 ns Receiver Output Disable Time Normal operation 200 ns 150 ns ⏐ tPHL - tPLH ⏐ Transmitter Skew (Note 4) ⏐ tPHL - tPLH ⏐ Receiver Skew MAX3233E 180 MAX3235E 50 ns ns VCC = 3.3V (MAX3233E), CL = 150pF 6 30 VCC = 5.0V (MAX3235E), to 1000pF TA = +25°C, Transition-Region Slew Rate = 3kΩ to 7kΩ, Note 2: A transmitter/receiver edge is defined asRaLtransition through the transmitter/receiver input logic thresholds. measured from +3Vpoints. to -3V CL = 150pF Note 3: Transmitter skew is measured at the transmitter zero cross 4 30 to 2500pF or -3V to +3V V/µs Note 4: Transmitter skew is measured at the transmitter zero crosspoints. __________________________________________Typical Operating Characteristics (VCC = +3.3V for MAX3233E, VCC = +5.0V for MAX3235E; 250kbps data rate; all transmitters loaded with 3kΩ and CL; TA = +25°C, unless otherwise noted.) OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE 2.5 0 -2.5 VOUT- -5.0 30 250kbps 25 20 120kbps 15 2000 3000 4000 LOAD CAPACITANCE (pF) 5000 SLEW RATE 10 8 SLEW RATE + 6 2 0 1000 12 20kbps 5 0 14 4 10 -7.5 -10.0 4 35 16 MAX3233E/35Etoc01 5.0 TRANSMITTER 1 AT DATA RATE TRANSMITTER 2 AT 1/16 DATA RATE 40 SLEW RATE (V/µs) VOUT+ 45 SUPPLY CURRENT (mA) 7.5 MAX3233E/35Etoc01 10.0 SLEW RATE vs. LOAD CAPACITANCE MAX3233E/35E toc02 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE TRANSMITTER OUTPUT VOLTAGE (V) MAX3233E/MAX3235E ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors 0 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 5000 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 5000 ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors PIN NAME 1 R2OUT 6 R1OUT 2 INVALID 3 T2IN 4 T1IN 5 FORCEON FUNCTION TTL/CMOS Receiver Outputs Invalid Signal Detector Output, active low. A logic high indicates that a valid RS-232 level is present on a receiver. TTL/CMOS Transmitter Outputs Force-On Input, active high. Drive high to override AutoShutdown Plus, keeping transmitters and receivers active (FORCEOFF must be high) (Table 1). 7 T1OUT 19 T2OUT 8 R1IN 20 R2IN 9 VCC 10 FORCEOFF 11, 12 V+ 13 C1+ Positive terminal of the internal voltage-doubling charge-pump capacitor. Leave unconnected or connect to an external 0.1µF capacitor. See Charge Pump Section. 14 C1- Negative terminal of the internal voltage-doubling charge-pump capacitor. Leave unconnected or connect to an external 0.1µF capacitor. See Charge Pump Section. 15 C2+ Positive terminal of the internal inverting charge-pump capacitor. Do not connect. 16 C2- Negative terminal of the internal inverting charge-pump capacitor. Do not connect. 17 V- 18 GND RS-232 Transmitter Outputs RS-232 Receiver Outputs Supply Voltage (MAX3233E = +3.3V, MAX3235E = +5.0V) Force-Off Input, active low. Drive low to shut down transmitters, receivers, and charge pump. This overrides AutoShutdown Plus and FORCEON (Table 1). +5.5V generated by the charge pump. Do not connect. -5.5V generated by the charge pump. Do not connect. Ground _______________________________________________________________________________________ 5 MAX3233E/MAX3235E ______________________________________________________________Pin Description MAX3233E/MAX3235E ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors _______________Detailed Description Dual Charge-Pump Voltage Converter The MAX3233E/MAX3235E’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), with no external capacitors. 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. POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER FORCEOFF FORCEON INVALID MAX3233E MAX3235E RS-232 Transmitters The transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The devices guarantee a 250kbps data rate with worstcase 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. 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. RS-232 Receivers The receivers convert RS-232 signals to CMOS-logic output levels. They feature inverting outputs that always remain active (Table 1). The MAX3233E/MAX3235E 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 2 and 3). AutoShutdown Plus Mode The devices achieve a 1µA supply current with Maxim’s AutoShutdown Plus feature, which operates when FORCEOFF is high and a FORCEON is low. When these devices do not sense a valid signal transition on any receiver or 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 CPU I/O CHIP WITH UART RS-232 Figure 1. Interface Under Control of PMU +0.3V R_IN -0.3V 80µs TIMER R INVALID ASSERTED IF ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 80µs. Figure 2a. INVALID Functional Diagram, INVALID Low +2.7V R_IN -2.7V 80µs TIMER R INVALID INVALID DEASSERTED IF ANY RECEIVER INPUT HAS BEEN ABOVE +2.7V OR BELOW -2.7V FOR 1µs. Figure 2b. INVALID Functional Diagram, INVALID High LapLink is a trademark of Traveling Software. 6 INVALID _______________________________________________________________________________________ ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors MAX3233E/MAX3235E Table 1. Output Control Truth Table FORCEON FORCEOFF VALID RECEIVER LEVEL Rx or Tx EDGE WITHIN 30sec T_OUT R_OUT Shutdown (Forced Off) X 0 X X High-Z Active Normal Operation (Forced On) 1 1 X X Active Active Normal Operation (AutoShutdown Plus) 0 1 X Yes Active Active Shutdown (AutoShutdown Plus) 0 1 X No High-Z Active Normal Operation INVALID* 1 Yes X Active Active Normal Operation INVALID* 1 X Yes Active Active Shutdown INVALID* 1 No No High-Z Active Normal Operation (AutoShutdown) INVALID* INVALID** Yes X Active Active Shutdown (AutoShutdown) INVALID* INVALID** No X High-Z Active OPERATION STATUS X = Don’t care * INVALID connected to FORCEON ** INVALID connected to FORCEON and FORCEOFF T_IN EDGE DETECT FORCEOFF FORCEOFF R_IN S 30sec TIMER EDGE DETECT AUTOSHDN* R FORCEON POWERDOWN* FORCEON AUTOSHDN * POWERDOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES. *AUTOSHDN IS ONLY AN INTERNAL SIGNAL. Figure 2c. AutoShutdown Plus Logic Figure 2d. Power-Down Logic 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. Figures 2a and 2b depict invalid and valid RS-232 receiver voltage levels. INVALID indicates the receiver input’s condition, and is independent of FORCEON and FORCEOFF states. Figure 2 and Tables 1 and 2 summarize the operating modes. FORCEON and FORCE- OFF 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, and the transmitter outputs are high impedance. The time required to exit shutdown is typically 100µs (Figure 7). _______________________________________________________________________________________ 7 By connecting FORCEON to INVALID, the device shuts down when no valid receiver level and no receiver or transmitter edge is detected for 30sec. It wakes up when a valid receiver level or receiver or transmitter edge is detected. By connecting FORCEON and FORCEOFF to INVALID, the device shuts down when no valid receiver level is detected and wakes up when a valid receiver level is detected. A system with AutoShutdown Plus may need time to wake up. Figure 4 shows a circuit that forces the transmitters on for 100ms, allowing enough time for another system to realize that the MAX3233E/ INVALID HIGH +2.7 RECEIVER INPUT LEVELS (V) MAX3233E/MAX3235E ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors INDETERMINATE MAX3235E is awake. If another 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. ±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs have extra protection against static electricity. Maxim’s engineers have developed state-of-the-art structures to protect these pins against ESD of ±15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD +0.3 0 Table 2. INVALID Truth Table INVALID LOW -0.3 INDETERMINATE RS-232 SIGNAL PRESENT AT ANY RECEIVER INPUT INVALID OUTPUT INVALID HIGH Yes High No Low -2.7 Figure 3a. Receiver Positive/Negative Thresholds for INVALID RECEIVER INPUTS INVALID } REGION TRANSMITTER INPUTS TRANSMITTER OUTPUTS INVALID OUTPUT VCC 0 tINVL tINVH tAUTOSHDN tAUTOSHDN tWU tWU V+ VCC 0 V- Figure 3b. AutoShutdown Plus, INVALID, and READY Timing Diagram 8 _______________________________________________________________________________________ ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors RC 50MΩ to 100MΩ MASTER SHDN LINE 0.1µF 1MΩ CHARGE CURRENT LIMIT RESISTOR FORCEOFF FORCEON HIGHVOLTAGE DC SOURCE MAX3233E MAX3235E Figure 4. AutoShutdown Plus Initial Turn-On to Wake Up Another System RC 1MΩ CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF Cs 150pF RD 330Ω DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST Figure 6a. IEC 1000-4-2 ESD Test Model ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to the following limits: RD 1500Ω DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR 1) ±15kV using the Human Body Model 2) ±8kV using the Contact Discharge method specified in IEC 1000-4-2 3) ±15kV using IEC 1000-4-2’s Air-Gap Discharge method ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test setup, test methodology, and test results. Figure 5a. Human Body ESD Test Model IP 100% 90% Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Figure 5b. Human Body Current Waveform event, Maxim’s E versions keep working without latchup, whereas competing RS-232 products can latch and must be powered down to remove latchup. Human Body Model Figure 5a shows the Human Body Model and Figure 5b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The MAX3233E/MAX3235E help you design equipment that meets Level 4 (the highest level) of IEC 1000-4-2, without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 1000-4-2 is higher peak current in IEC 1000-4-2, because series resistance is lower in the IEC 1000-4-2 model. Hence, the ESD withstand voltage measured to IEC 1000-4-2 is generally lower than _______________________________________________________________________________________ 9 MAX3233E/MAX3235E POWERMANAGEMENT UNIT VCC I CBYPASS 100% VCC 90% I PEAK MAX3233E/MAX3235E ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors MAX3233E MAX3235E T_ OUT T_ IN 10% R_ IN R_ OUT t r = 0.7ns to 1ns t 30ns 5kΩ FORCEON 1000pF 60ns VCC Figure 6b. IEC 1000-4-2 ESD Generator Current Waveform FORCEOFF GND Figure 8. Loopback Test Circuit 5V/div 0 FORCEON = FORCEOFF T1OUT 2V/div 0 manufacturing. Of course, all pins require this protection during manufacturing, not just RS-232 inputs and outputs. Therefore, after PC board assembly, the Machine Model is less relevant to I/O ports. __________Applications Information Charge Pumps 10V/div 0 T2OUT VCC = 3.3V 10µs/div Figure 7. Transmitter Outputs when Exiting Shutdown or Powering Up that measured using the Human Body Model. Figure 6a shows the IEC 1000-4-2 model, and Figure 6b shows the current waveform for the ±8kV, IEC 1000-4-2, Level 4, ESD contact-discharge test. The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized. Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during 10 The MAX3233E/MAX3235E do not require external capacitors to operate their internal charge pumps. The MAX3235E can be operated down to 3.0V by paralleling the internal C1 capacitor with an external 0.1µF. When using an external capacitor across the C1 terminals, check to confirm that the total supply voltage measured from V+ to V- does not exceed the absolute maximum voltage of 13V. With the external 0.1µF capacitor added, the MAX3235E should not be used with a supply greater than +3.9V. Power-Supply Decoupling In most applications, a 0.1µF VCC bypass capacitor is adequate. Connect bypass capacitors as close to the IC as possible. Transmitter Outputs when Exiting Shutdown Figure 7 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). ______________________________________________________________________________________ ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors High Data Rates Interconnection with 3V and 5V Logic The MAX3233E/MAX3235E 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 250kbps. For The MAX3233E/MAX3235E can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 3 for more information on possible combinations of interconnections. 5V/div T1IN 5V/div T1IN 5V/div 5V/div T1OUT T1OUT 5V/div R1OUT 5V/div R1OUT VCC = 3.3V (MAX3233E), VCC = 5.0V (MAX3235E) VCC = 3.3V (MAX3233E), VCC = 5.0V (MAX3235E) 2µs/div 2µs/div Figure 10. Loopback Test Result at 250kbps Figure 9. Loopback Test Result at 120kbps Table 3. Logic Family Compatibility with Various Supply Voltages DEVICE LOGIC POWER-SUPPLY VOLTAGE (V) VCC SUPPLY VOLTAGE (V) MAX3233E 3.3 3.3 Compatible with all CMOS families MAX3233E 5 3.3 Compatible with ACT and HCT CMOS, and with AC, HC, or CD4000 CMOS MAX3235E 3.3/5 5 Compatible with all TTL and CMOS families COMPATIBILITY ______________________________________________________________________________________ 11 MAX3233E/MAX3235E Figure 9, all transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 10, a single transmitter was driven at 250kbps, and all transmitters were loaded with an RS-232 receiver in parallel with 250pF. 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. MAX3233E/MAX3235E ±15kV ESD-Protected, 1µA, 250kbps, 3.3V/5V, Dual RS-232 Transceivers with Internal Capacitors Typical Operating Circuit PART VCC CBYPASS 9 0.1µF 13 C1+ 14 C115 16 C2+ MAX3235ECWP VCC 11, 12 MAX3235ECPP MAX3235EEWP MAX3235EEPP V+ MAX3233E MAX3235E V- 17 TEMP RANGE PIN-PACKAGE 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C 20 SO 20 Plastic DIP 20 SO 20 Plastic DIP ___________________Chip Information C2- 4 T1IN TTL/CMOS INPUTS Ordering Information (continued) T1OUT T2OUT 3 T2IN R1IN 6 R1OUT TTL/CMOS OUTPUTS 7 19 RS-232 INPUTS R2IN TRANSISTOR COUNT: 1129 Package Information 8 5kΩ 1 R2OUT RS-232 OUTPUTS For the latest package outline information, go to www.maxim-ic.com/packages. 20 5kΩ AUTOSHUTDOWN PLUS INVALID 2 FORCEOFF 10 FORCEON VCC 5 GND 18 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circu implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. it patent licenses are 12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.