19-4343; Rev 0; 10/08 3Mbps RS-232 Transceivers with Low-Voltage Interface ♦ Data Rate Up to 3Mbps ♦ Low-Voltage Logic Interface ♦ +3V to +5.5V Supply Voltage ♦ AutoShutdown Plus ♦ 1µA Shutdown Current Functional Diagrams 1.62V to VCC VL GPS Systems POS Systems Industrial Systems Communication Systems Portable Devices Data Cables VCC C1+ V+ C1 C3 C1- MAX13234E MAX13235E C2+ V- C2 C4 C2T1IN T1OUT T2IN T2OUT RS-232 OUTPUTS TTL/CMOS INPUTS R1OUT TTL/CMOS OUTPUTS R2OUT Wireless Modules CBYPASS2 CBYPASS1 Applications Telematics 3.0V to 5.5V LOGIC-LEVEL TRANSLATION The MAX13234E–MAX13237E are +3V to +5.5V powered EIA/TIA-232 and V.28/V.24 communications interfaces with high data-rate capabilities (up to 3Mbps), a flexible logic voltage interface, and enhanced electrostatic discharge (ESD) protection. All receiver inputs and transmitter outputs are protected to ±15kV IEC 61000–4-2 Air Gap Discharge, ±8kV IEC 61000-4-2 Contact Discharge, and ±15kV Human Body Model. The MAX13234E/MAX13235E have two receivers and two transmitters, while the MAX13236E/MAX13237E have a single receiver and transmitter. The transmitters have a low-dropout transmitter output stage, delivering true RS-232 performance from a +3V to +5.5V supply based on a dual charge pump. The charge pump requires only four small 0.1µF capacitors for operation from a +3.3V supply. All devices achieve a 1µA supply current using Maxim’s AutoShutdown Plus™ feature. These devices automatically enter a low-power shutdown mode when the RS-232 cable is disconnected or the devices driving the transmitter and receiver inputs are inactive for more than 30s. The MAX13234E–MAX13237E are available in spacesaving TQFN and TSSOP packages and operate over the -40°C to +85°C extended temperature range. Features R1IN 5kΩ RS-232 INPUTS R2IN FORCEOFF 5kΩ FORCEON READY GND Functional Diagrams continued at end of data sheet. AutoShutdown Plus is a registered trademark of Maxim Integrated Products, Inc. Ordering Information/Selector Guide DRIVERS/ RECEIVERS MAXIMUM DATA RATE TEMP RANGE PIN-PACKAGE MAX13234EEUP+ 2x2 250kbps -40°C to +85°C 20 TSSOP MAX13234EETP+ 2x2 250kbps -40°C to +85°C 20 TQFN-EP* MAX13235EEUP+ 2x2 3Mbps -40°C to +85°C 20 TSSOP MAX13235EETP+ 2x2 3Mbps -40°C to +85°C 20 TQFN-EP* MAX13236EETE+ 1x1 250kbps -40°C to +85°C 16 TQFN-EP* MAX13237EETE+ 1x1 3Mbps -40°C to +85°C 16 TQFN-EP* PART +Denotes a lead-free/RoHS-compliant package. *EP = Exposed pad. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX13234E–MAX13237E General Description MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) VCC ...................................................................... -0.3V to +6.0V VL ......................................................................... -0.3V to +6.0V V+ ........................................................................ -0.3V to +7.0V V- ......................................................................... +0.3V to -7.0V (V+) + |(V-)| ..................................................................... +13.0V T_IN, FORCEOFF, FORCEON ..................... -0.3V to (VL + 0.3V) R_IN ................................................................................... ±25V T_OUT.............................................................................. ±13.2V R_OUT, READY ........................................... -0.3V to (VL + 0.3V) Short-Circuit Duration T_OUT to GND ......................................................... Continuous Continuous Power Dissipation (TA = +70°C) 16-Pin TQFN (derate 20.8mW/°C above +70°C) ..... 1666mW 20-Pn TSSOP (derate 10.9mW/°C above +70°C) ...... 879mW 20-Pin TQFN (derate 21.3mW/°C above +70°C) ..... 1702mW Junction-to-Case Thermal Resistance (θJC) (Note 1) 16-Pin TQFN ................................................................. 2°C/W 20-Pin TSSOP ............................................................. 20°C/W 20-Pin TQFN ................................................................. 2°C/W Junction-to-Ambient Thermal Resistance (θJA) (Note 1) 16-Pin TQFN ............................................................... 30°C/W 20-Pin TSSOP ............................................................. 73°C/W 20-Pin TQFN ............................................................... 29°C/W Operating Temperature Range MAX1323x Operating Temperature Range .... -40°C to +85°C MAX1323x Operating Temperature Range .. -40°C to +105°C Storage Temperature Range ........................... -65°C to +160°C Lead Temperature (soldering, 10s) .................................+300ºC Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. 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, VL = +1.62V to VCC, TA = -40°C to +85°C, C1–C4 = 0.1µF, VCC = VL, tested at 3.3V ±10%. Typical values are at TA = +25°C.) (Note 2) PARAMETER Supply Voltage Logic Supply Voltage SYMBOL MAX UNITS VCC CONDITIONS MIN 3 5.5 V VL 1.62 VCC V mA FORCEOFF = FORCEON = VL, no loads VCC Supply Current VCC Shutdown Current VL Supply Current VL Shutdown Current ICC ICCSH IL ILSH TYP 0.3 1 VL = 0V 1 10 AutoShutDown Plus, FORCEOFF = VL, FORCEON = GND, all R_IN idle, all T_IN idle. 1 10 FORCEOFF = GND 1 10 µA VCC = +5.5V 1 10 µA FORCEOFF = GND 1 10 µA 1/3 x VL V µA LOGIC INPUTS (T_IN, FORCEON, FORCEOFF, Referred to VL) Input Threshold Low VIL Tested at room temperature only Input Threshold High VIH Tested at room temperature only Input Hysteresis 2/3 x VL V 60 Input Leakage Current ±0.01 mV ±1 µA 0.4 V RECEIVER OUTPUTS (READY) Output-Voltage Low VOL IOUT = 0.8mA Output-Voltage High VOH IOUT = -0.5mA 2 VL - 0.6 VL - 0.1 _______________________________________________________________________________________ V 3Mbps RS-232 Transceivers with Low-Voltage Interface (VCC = +3V to +5.5V, VL = +1.62V to VCC, TA = -40°C to +85°C, C1–C4 = 0.1µF, VCC = VL, tested at 3.3V ±10%. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS +25 V RECEIVER INPUTS Input-Voltage Range -25 Input Threshold Low VIL TA = +25°C Input Threshold High VIH TA = +25°C VCC = +3.3V 0.6 1.2 VCC = +5V 0.8 1.5 V VCC = +3.3V 1.5 2.4 VCC = +5V 1.8 2.4 Input Hysteresis 0.5 Input Resistance 3 5 V V 7 kΩ TRANSMITTER OUTPUTS Output-Voltage Swing All transmitter outputs loaded with 3kΩ to GND ±5 ±5.4 V Output Resistance VCC = V+ = V- = 0V, transmitter outputs = ±2V 300 10M Ω Output Short-Circuit Current VCC = 0V or +3V to +5.5V, VOUT = ±12V, transmitters disabled Output Leakage Current -60 +60 mA -25 +25 µA 2.7 V AutoShutdown Plus (FORCEON = GND, FORCEOFF = VL) Positive threshold, Figure 1 Receiver Input Threshold Valid Level Receiver Input Threshold Invalid Level Receiver or Transmitter Edge-toTransmitters Enabled Receiver or Transmitter Edge-toTransmitters Shutdown tWU Negative threshold, Figure 1 -2.7 Figure 1 -0.3 VL = 5V, Figure 1 (Note 3) tAUTOSHDN VL = 5V, Figure 1 (Note 3) V +0.3 100 15 30 V µs 60 s TIMING CHARACTERISTICS (MAX13234E/MAX13236E) RL = 3kΩ, CL = 1000pF, one transmitter switching Maximum Data Rate 250 kbps Receiver Propagation Delay tRPHL, tRPLH CL = 150pF, Figures 2, 3 0.15 µs Transmitter Skew |tTPHL tTPLH| Figures 4, 5 (Note 4) 100 ns Receiver Skew |tRPHL tRPLH| Figures 2, 3 50 ns _______________________________________________________________________________________ 3 MAX13234E–MAX13237E ELECTRICAL CHARACTERISTICS (continued) MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface ELECTRICAL CHARACTERISTICS (continued) (VCC = +3V to +5.5V, VL = +1.62V to VCC, TA = -40°C to +85°C, C1–C4 = 0.1µF, VCC = VL, tested at 3.3V ±10%. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL Transition-Region Slew Rate CONDITIONS MIN VCC = +3.3V, TA = +25°C, RL = 3kΩ to 7kΩ, measured from +3V to -3V or -3V to +3V, one transmitter switching, CL = 150pF to 1000pF 6 TYP MAX UNITS 30 V/µs TIMING CHARACTERISTICS (MAX13235E/MAX13237E) Maximum Data Rate Receiver Propagation Delay tRPHL, tRPLH RL = 3kΩ, CL = 250pF, one transmitter switching 1 RL = 3kΩ, CL = 150pF, one transmitter switching 3 Mbps CL = 150pF, Figures 2, 3 0.15 µs Transmitter Skew |tTPHL – tTPLH| Figures 4, 5 (Note 4) 25 ns Receiver Skew |tRPHL – tRPLH| Figures 2, 3 50 ns Transition-Region Slew Rate VCC = +3.3V, TA = +25°C, RL = 3kΩ to 7kΩ, measured from T_OUT = +3V to -3V or -3V to +3V, one transmitter switching, CL = 150pF to 1000pF 24 150 V/µs ESD PROTECTION R_IN, T_OUT to GND Human Body Model ±15 IEC 61000-4-2 Air Discharge ±15 IEC 61000-4-2 Contact Discharge ±8 Note 2: All devices are 100% production tested at TA = +85°C. All temperature limits are guaranteed by design. Note 3: A transmitter/receiver edge is defined as a transition through the transmitter/receiver input-logic thresholds. Note 4: Transmitter skew is measured at the transmitter zero cross points. 4 _______________________________________________________________________________________ kV 3Mbps RS-232 Transceivers with Low-Voltage Interface RECEIVER INPUTS TRANSMITTER INPUTS TRANSMITTER OUTPUTS tAUTOSHDN VCC READY tWU tAUTOSHDN tWU 0 V+ V+ VCC 0 VV- Figure 1. AutoShutdown Plus, and READY Timing Diagram T_IN T_OUT R_IN R_OUT CL Figure 2. Receiver Test Circuit _______________________________________________________________________________________ 5 MAX13234E–MAX13237E Test Circuits/Timing Diagram MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface Test Circuits/Timing Diagram (continued) R_IN tR, tF ≤ 10ns 1.3V tRPHL 1.7V tRPLH VOH R_OUT VOL VL/2 VL/2 Figure 3. Receiver Propagation Delay T_IN T_OUT VO RL CL Figure 4. Transmitter Test Circuit VL tR, tF ≤ 10ns VL/2 T_IN 0 VL/2 tTPHL tTPLH VO 3V 3V 0 0 T_OUT -3V -3V -VO tF SRF = 6/tF SRR = 6/tR tR Figure 5. Transmitter Propagation Delay 6 _______________________________________________________________________________________ 3Mbps RS-232 Transceivers with Low-Voltage Interface TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 0 MAX13234E/MAX13236E RL = 3kΩ T1 AT 250kbps -2 MAX13234E toc02 2 0 MAX13235E/MAX13237E RL = 3kΩ T1 AT 3Mbps -2 12 MAX13234E/MAX13236E RL = 3kΩ 11 10 SLEW RATE (V/μs) OUTPUT VOLTAGE (V) 2 V+ 4 OUTPUT VOLTAGE (V) V+ 4 SLEW RATE vs. LOAD CAPACITANCE 6 MAX13234E toc01 6 9 MAX13234E toc03 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE SR+ 8 7 SR- 6 -4 V- -6 500 1000 1500 2000 2500 50 100 150 200 250 0 300 2000 SLEW RATE vs. LOAD CAPACITANCE VCC SUPPLY CURRENT vs. LOAD CAPACITANCE VCC SUPPLY CURRENT vs. LOAD CAPACITANCE SR+ 50 20 15 10 100 150 200 250 30 25 20 15 5 0 300 MAX13235E 10 0 40 RL = 3kΩ T1 AT 3Mbps T2 AT 187.5kbps 35 5 45 500 1000 1500 2000 50 2500 100 150 200 250 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) TRANSMITTER SKEW vs. LOAD CAPACITANCE TRANSMITTER SKEW vs. LOAD CAPACITANCE READY TURN-ON TIME vs. TEMPERATURE 70 50 30 7 6 5 4 3 2 300 100 MAX13234E toc09 MAX13235E/MAX13237E RL = 3kΩ 1 TRANSMITTER OPERATING AT 3Mbps 8 90 READY TURN-ON TIME (μs) 90 9 MAX13234E toc08 MAX13234E/MAX13236E RL = 3kΩ 1 TRANSMITTER OPERATING AT 250kbps TRANSMITTER SKEW (ns) MAX13234E toc07 150 2500 40 MAX13234E toc05 MAX13234E SUPPLY CURRENT (mA) 60 RL = 3kΩ T1 AT 250kbps T2 AT 15.6kbps 25 SUPPLY CURRENT (mA) SR- 55 30 MAX13234E toc04 65 110 1500 LOAD CAPACITANCE (pF) 70 130 1000 LOAD CAPACITANCE (pF) MAX13235E/MAX13237E RL = 3kΩ 50 500 LOAD CAPACITANCE (pF) 75 SLEW RATE (V/μs) 4 -6 0 TRANSMITTER SKEW (ns) 5 V- MAX13234E toc06 -4 80 70 60 50 10 1 -10 0 0 500 1000 1500 2000 LOAD CAPACITANCE (pF) 2500 40 50 100 150 200 LOAD CAPACITANCE (pF) 250 -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 7 MAX13234E–MAX13237E Typical Operating Characteristics (VCC = VL = 3.3V, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = VL = 3.3V, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. DATA RATE 1.4 1.2 1.0 0.8 0.6 25 MAX13235E 1 TRANSMITTER OPERATING RL = 3kΩ, CL = 150pF 20 15 10 0.4 0 2.1 -15 10 35 60 1.7 1.5 1.1 0.9 0.5 0.01 TEMPERATURE (°C) 0.1 1 2.5 3.5 VL (V) V+ 4 MAX13235E/MAX13237E RL = 3kΩ, CL = 150pF 1 TRANSMITTER OPERATING AT 1Mbps -4 8 6 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 6 -2 1.5 TRANSMITTER OUTPUT VOLTAGE vs. LOAD CURRENT MAX13234E toc13 8 0 10 DATA RATE (kbps) TRANSMITTER OUTPUT VOLTAGE vs. SUPPLY VOLTAGE 2 VIL 1.3 0.7 0 0.001 85 VIH 1.9 V+ 4 2 1 TRANSMITTER OPERATING, DC 0 -2 -4 V- -6 MAX13234E toc14 -40 VCC = 5.5V 2.3 5 0.2 V- -6 -8 -8 3.0 3.5 4.0 4.5 SUPPLY COLTAGE (V) 8 2.5 LOGIC-INPUT THRESHOLD (V) SUPPLY CURRENT (mA) 1.6 30 MAX13234E toc11 1.8 LOGIC-INPUT THRESHOLD vs. VL 35 MAX13234E toc10 2.0 MAX13234E toc12 READY TURN-OFF TIME vs. TEMPERATURE READY TURN-OFF TIME (μs) MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface 5.0 5.5 0 2 4 6 8 LOAD CURRENT (mA) _______________________________________________________________________________________ 4.5 5.5 3Mbps RS-232 Transceivers with Low-Voltage Interface PIN MAX13234E/ MAX13235E MAX13236E/ MAX13237E NAME FUNCTION TSSOP TQFN-EP TQFN-EP 1 19 14 READY 2 1 16 C1+ 3 20 15 V+ +5.5V Generated by the Charge Pump 4 2 1 C1- Negative Terminal of the Voltage Doubler Charge-Pump Capacitor 5 3 2 C2+ Positive Terminal of the Inverting Charge-Pump Capacitor 6 4 3 C2- Negative Terminal of the Inverting Charge-Pump Capacitor 7 5 4 V- 8 6 — T2OUT — — 5 RIN RS-232 Receiver Input 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 the Voltage Doubler Charge-Pump Capacitor -5.5V Generated by the Charge Pump RS-232 Transmitter Output 2 9 7 — R2IN RS-232 Receiver Input 2 — — 6 ROUT CMOS Receiver Output. VL referred logic. 10 8 — R2OUT CMOS Receiver Output 2. VL referred logic. 11 9 7 VL Logic-Level Supply. All CMOS inputs and outputs are related to this supply. — — 8 TIN CMOS Transmitter Input. VL referred logic. 12 10 — T2IN CMOS Transmitter Input 2. VL referred logic. 13 11 — T1IN CMOS Transmitter Input 1. VL referred logic. 14 12 9 FORCEON 15 13 — R1OUT FORCEON Input, Active-High. VL referenced logic. Drive FORCEON high to override automatic circuitry keeping transmitters on (FORCEOFF must be high). See Table 1. CMOS Receiver Output 1. VL referred logic. — — 10 TOUT RS-232 Transmitter Output 16 14 — R1IN RS-232 Receiver Input 1 17 15 — T1OUT 18 16 11 GND Ground 19 17 12 VCC +3V to +5.5V Supply Voltage 20 18 13 FORCEOFF — — — EP RS-232 Transmitter Output 1 FORCEOFF Input, Active-Low. VL referenced logic. Drive FORCEOFF low to shut down transmitters and on-board charge pumps. All receiver and transmitter outputs are tristated. This overrides all automatic circuitry and FORCEON (Table 1). Exposed Pad. Connect EP to GND or leave unconnected. _______________________________________________________________________________________ 9 MAX13234E–MAX13237E Pin Descriptions MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface Detailed Description VL Logic Supply Input The MAX13234E–MAX13237E feature a separate logic supply input (VL) that sets the receiver’s output level (VOH), and sets the transmitter’s input thresholds (VIL, V IH ). This feature allows flexibility in interfacing to UARTs or communication controllers that have different logic levels. Connect this input to the host logic supply (1.62V ≤ VL ≤ VCC). Dual Charge-Pump Voltage Converter The internal power supply consists of a regulated dual charge pump that provides output voltages of +5.5V 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. The charge pumps require flying capacitors (C1, C2) and reservoir capacitors (C3, C4) to generate the V+ and Vsupplies. The READY output is low when the charge pumps are disabled in shutdown mode. The READY signal asserts high when V- goes below -4V. RS-232 Transmitters The transmitters are inverting level translators that convert CMOS-logic levels to ±5.0V EIA/TIA-232 levels. The MAX13234E/MAX13236E guarantee a 250kbps data rate with worst-case loads of 3kΩ in parallel with 1000pF. The MAX13235E/MAX13237E guarantee a 1Mbps data rate with worst-case loads of 3kΩ in parallel with 250pF, and a 3Mbps data rate with worst-case loads of 3kΩ in parallel with 150pF. Transmitters can be paralleled to drive multiple receivers. When FORCEOFF is driven to ground or when the AutoShutdown Plus circuitry senses that all receiver and transmitter inputs are inactive for more than 30s, the transmitters are disabled and the outputs go into a high-impedance state. When powered off or shut down, the outputs can be driven to ±12V. The transmitter inputs do not have pullup resistors. Connect unused inputs to GND or VL. RS-232 Receivers The receivers convert RS-232 signals to CMOS-logic output levels. The MAX13234E–MAX13237E have inverting outputs that are active when in shutdown (FORCEOFF = GND) (Table 1). AutoShutdown Plus Mode Drive FORCEOFF high and FORCEON low to invoke AutoShutdown Plus mode. When these devices do not sense a valid signal transition on any receiver and transmitter input for 30s, the onboard charge pumps are shut down, reducing supply current to 1µA. This occurs if the RS-232 cable is disconnected or if the devices driving the transmitter and receiver inputs are inactive for more than 30s. The MAX13234E–MAX13237E turn on again when a valid transition is applied to any RS-232 receiver or transmitter input. As a result, the system saves power without requiring any control. Figure 6 and Table 1 summarize the MAX13234E– MAX13237E operating modes. The FORCEON and FORCEOFF inputs 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. Hardware-Controlled Shutdown Drive FORCEOFF low to place the MAX13234E– MAX13237E into shutdown mode. POWERMANAGEMENT UNIT MASTER SHDN LINE 0.1μF 1MΩ FORCEOFF FORCEON MAX13234E MAX13235E MAX13236E MAX13237E Figure 7. AutoShutdown Plus Initial Turn-On to Wake Up a Mouse or Another System 10 ______________________________________________________________________________________ 3Mbps RS-232 Transceivers with Low-Voltage Interface R_IN EDGE DETECT EDGE DETECT FORCEOFF FORCEOFF S 30s TIMER AUTOSHDN POWERDOWN* FORCEON R * POWERDOWN IS ONLY AN INTERNAL SIGNAL. IT CONTROLS THE OPERATIONAL STATUS OF THE TRANSMITTERS AND THE POWER SUPPLIES. FORCEON Figure 6. AutoShutdown Plus and Shutdown Logic Table 1. Transceiver Mode Control R_IN or T_IN EDGE WITHIN 30s T_OUT R_OUT X X High-Impedance Active Shutdown (Forced Off) 1 X Active Active Normal Operation (Forced On) 1 0 Yes Active Active Normal Operation in AutoShutdown Plus 1 0 No High-Impedance Active Shutdown in AutoShutdown Plus FORCEOFF FORCEON 0 1 TRANSCEIVER STATUS X = Don’t Care. ______________________________________________________________________________________ 11 MAX13234E–MAX13237E T_IN ±15kV ESD Protection ESD-protection structures are incorporated on all pins to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the MAX13234E–MAX13237E 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 RC 1MΩ CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF an ESD event, Maxim’s E versions keep working without latchup. ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to the following limits: 1) ±15V Using the Human Body Model 2) ±15kV Using IEC 61000-4-2 Air-Gap Method 3) ±8kV Using IEC 61000-4-2 Contact-Discharge Method RC 50MΩ to 100MΩ RD 1500Ω DISCHARGE RESISTANCE CHARGE-CURRENT LIMIT RESISTOR DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR Figure 8a. Human Body ESD Test Model HIGHVOLTAGE DC SOURCE RD 330Ω Cs 150pF STORAGE CAPACITOR DEVICE UNDER TEST Figure 9a. IEC61000-4-2 ESD Test Model I IP 100% 90% Ir 100% PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) 90% AMPERES I PEAK MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Figure 8b. Human Body Current Waveform 10% t r = 0.7ns to 1ns t 30ns 60ns Figure 9b. IEC61000-4-2 ESD Generator Current Waveform 12 ______________________________________________________________________________________ 3Mbps RS-232 Transceivers with Low-Voltage Interface Human Body Model Figure 8a shows the Human Body Model and Figure 8b 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 61000-4-2 The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The MAX13234E– MAX13237E helps design equipment that meets Level 4 (the highest level) of IEC 61000-4-2, without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 61000-4-2 is higher peak current in IEC 61000-4-2, because series resistance is lower in the IEC 61000-4-2 model. Hence, the ESD withstand voltage measured to IEC 61000-4-2 is generally lower than that measured using the Human Body Model. Figure 9a shows the IEC 61000-4-2 model and Figure 9b shows the current waveform for the 8kV, IEC 61000-4-2, Level 4, ESD Contact-Discharge Method. The Air-Gap Method involves approaching the device with a charged probe. The Contact-Discharge Method connects the probe to the device before the probe is energized. Applications Information larger nominal value. The capacitor’s equivalent series resistance (ESR), usually rises at low temperatures influencing the amount of ripple on V+ and V-. Table 2. Required Minimum Capacitance Values VCC (V) C1, CBYPASS2 (µF) CBYPASS1 (µF) C2, C3, C4 (µF) 3.0 to 3.6 0.22 0.22 0.22 3.15 to 3.6 0.1 0.1 0.1 4.5 to 5.5 0.047 1 0.33 3.0 to 5.5 0.22 1 1 Power-Supply Decoupling In most circumstances, a 0.1µF VCC bypass capacitor and a 1µF VL bypass capacitor are adequate. In applications that are sensitive to power-supply noise, use capacitors of the same value as charge-pump capacitor C1. Connect bypass capacitors as close to the IC as possible. Transmitter Outputs when Exiting Shutdown Figure 10 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. Capacitor Selection The capacitor type used for C1–C4 is not critical for proper operation; polarized or non-polarized capacitors can be used. The charge pump requires 0.1µF capacitors for VCC = +3.3V operation. For other supply voltages, see Table 2 for required capacitor values. Do not use values smaller than those listed in Table 2. 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, CBYPASS1, and CBYPASS2 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 5V/div 0 FORCEON = FORCEOFF T1OUT 2V/div 0 5V/div 0 T2OUT VCC = 3.3V C1–C4 = 0.1μF READY 5μs/div Figure 10. Transmitter Outputs when Exiting Shutdown or Powering Up ______________________________________________________________________________________ 13 MAX13234E–MAX13237E 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. MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface High Data Rates The MAX13234E–MAX13237E maintain the RS-232 ±5V minimum transmitter output voltage even at high data rates. Figure 11 shows a transmitter loopback test circuit. Figure 12 shows a loopback test result at 120kbps, and Figure 13 shows the same test at 3Mbps. 1.62V to VCC In Figure 12, all transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. In Figure 13, a single transmitter was driven at 3Mbps, and all transmitters were loaded with an RS-232 receiver in parallel with 150pF. VCC 3V/div T1IN CBYPASS1 CBYPASS2 VL 5V/div VCC T1OUT C1+ V+ C1 C3* C1C2+ 5V/div R1OUT MAX13236E MAX13237E VCC = 3.3V V- C2 C4 2μs/div C2- R_IN R_OUT FORCEON VCC Figure 12. Loopback Test Results at 120kbps T_OUT T_IN 5kΩ 1000pF 3.3V/div T1IN FORCEOFF T1OUT GND 5V/div *C3 CAN BE RETURNED TO VCC OR GND. 3.3V/div R1OUT VCC = 3.3V Figure 11. Loopback Test Circuit 100ns/div Figure 13. Loopback Test Results at 3Mbps Chip Information PROCESS: BiCMOS 14 ______________________________________________________________________________________ 3Mbps RS-232 Transceivers with Low-Voltage Interface TOP VIEW 13 12 11 GND R1IN C2- 6 15 R1OUT V- 7 14 FORCEON T2OUT 8 13 T1IN R2IN 9 12 T2IN R2OUT 10 11 VL VCC 17 FORCEOFF 18 READY 19 V+ 20 MAX13234E MAX13235E *EP + 1 2 TSSOP 3 4 5 V- T1OUT 16 C2- 17 C2+ MAX13234E MAX13235E C1- 5 C1+ 4 16 10 T2IN 9 VL 8 R2OUT 7 R2IN 6 12 11 10 9 FORCEOFF 13 8 TIN READY 14 7 VL V+ 15 6 ROUT C1+ 16 5 RIN T2OUT TQFN MAX13236E MAX13237E *EP + 1 2 3 4 TQFN *EXPOSED PAD. CONNECT EP TO GND. *EXPOSED PAD. CONNECT EP TO GND. Functional Diagrams (continued) 1.62V to VCC 3.0V to 5.5V CBYPASS2 CBYPASS1 VL VCC C1+ V+ C1 C3 C1- MAX13236E MAX13237E C2+ V- C2 C4 C2- TTL/CMOS INPUT T_IN TTL/CMOS OUTPUT R_OUT FORCEOFF FORCEON T_OUT LOGIC-LEVEL TRANSLATION C1C2+ GND FORCEON 14 18 V- T1IN 15 3 TOUT FORCEON VCC V+ GND R1OUT 19 C2- FORCEOFF 2 C2+ 20 C1+ + VCC 1 C1- READY R1IN TOP VIEW T1OUT TOP VIEW R_IN RS-232 OUTPUT RS-232 INPUT 5kΩ READY GND ______________________________________________________________________________________ 15 MAX13234E–MAX13237E Pin Configurations MAX13234E–MAX13237E 3Mbps RS-232 Transceivers with Low-Voltage Interface Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 20 TSSOP U20-2 21-0066 20 TQFN-EP* T2055-5 21-0140 16 TQFN-EP* T1655-2 21-0140 *EP = Exposed Pad. 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 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.