19-1437: Rev 0; 3/99 MAAS +15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver General Description The MAX3385E is a 3V-powered EIA/TIA-232 and V.28/V.24 communications interface with low power requirements, high data-rate capabilities, and en- hanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to +15kV using IEC 1000-4-2 Air-Gap Discharge, +8kV using IEC 1000-4-2 Contact Discharge, and +15kV using the Human Body Model. The transceiver has a proprietary low-dropout transmit- ter output stage, delivering true RS-232 performance from a +3.0V to +5.5V supply with a dual charge pump. The charge pump requires only four small 0.1pF capac- itors for operation from a +3.3V supply. Each device is guaranteed to run at data rates of 250kbps while main- taining RS-232 output levels. The MAX3385E has two receivers and two drivers. It features a 1A shutdown mode that reduces power con- sumption and extends battery life in portable systems. lis receivers can remain active in shutdown mode, allowing external devices such as modems to be moni- tored using only 1A supply current. The MAX3385E is available in a space-saving SSOP package in either the commercial (0C to +70C) or extended-industrial (-40C to +85C) temperature range. Applications Battery- Powered Hand-Held Equipment Features ESD Protection for RS-232 I/O Pins +15kVHuman Body Model +8kVIEC 1000-4-2, Contact Discharge +15kVIEC 1000-4-2, Air-Gap Discharge Latchup Free 300pA Supply Current 1pA Low-Power Shutdown with Receivers Active 250kbps Guaranteed Data Rate 250us Time to Exit Shutdown with 3kQ Load on V+ 6V/ps Guaranteed Slew Rate Meets EIA/TIA-232 Specifications Down to 3.0V fet eh OH OOH hh Hh OH Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX3385ECAP 0C to +70C 20 SSOP MAX3385EEAP -40C to +85C 20 SSOP Typical Operating Circuit Peripherals Equipment Printers Pin Configuration TOP VIEW ne. L 120] SHDN c+ [2] 19] Voc vs La 18] GND ct La] AA AX AA [7] TOUT cos[5] MAX3385E Tie] RIIN c2-[6| 115] RIOUT v- [7 14] THIN Te0uT[ 8 | ha] TIN ren [9] 12] ReOUT Ne. [ro] 14] Ne. SsoP +3,3V tt 19 Cpypass = Vec atl 4" Vs oF T__4|o, AAAXLAA MAX3385E 5 C2+ V- C2 _|+ O1mF T_ 6 C2. 149 T1IN > TIOUT 417 | RS-232 OUTPUTS TTU.CMOS INPUTS oo TAIN T2OUT | 8 ~ >} > RIOUT RAIN 16 <}__ 129 ReOUT = RING9 <<} __ < a TTUCMOS OUTPUTS RS-232 INPUTS * C3 CAN BE RETURNED TO ETHER Vcc OR GROUND. NOTE: SEE TABLE 2 FOR CAPACITOR SELECTION +Covered by U.S. Patent numbers 4,636,930; 4,679,134; 4,777,577; 4,797,899; 4,809,152; 4,897,774; 4,999,761; and other patents pending. MAXIM Maxim Integrated Products 1 For free samples & the latest literature: http://)www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. sdGEEEXVWNMAX3385E +15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver ABSOLUTE MAXIMUM RATINGS VCC tO GND. .....ccecceccessssssessseeeceeceeeeeeeeeseesesessssssnnsaeees -0.3V to +6V V+ to GND (Note 1)..... -0.3V to +7V V- to GND (Note 1)... +0.3V to -7V V+ + [V-] (NOtG 1) oe eee eee ee reece renee eeecaeeeenaeeereeeeeaeeeeeaees +13V Input Voltages T_IN, SHDN to GND ........ccceccececcecesssseeeeeeesseeeeeees -0.3V to +6V PIN to GND 20. cccceceeceeeeeeeesesssseeaeeaesaecceseeseeeeeesesseesess +25V Output Voltages T_OUT to GND... ooo. eeccecccceceeeceseesssseseeeaecaeceecceeeeeeeesesseeeess +13.2V ROUT Doo eccccccccccecceeceeeesessssssssssessesaseeeeees -0.3V to (Vcc + 0.3V) Short-Circuit Duration, TOUT to GND.............:0cee Continuous Continuous Power Dissipation (Ta = +70C) SSOP (derate 8.00mW/C above +70C) wo. 640mWwW Operating Temperature Ranges MAX3385ECAP |... sect sec cee eeeee essence eneaseaenees 0C to +70C MAX3385EEAP -40C to +85C Storage Temperature Range ....... cesses -65C to + 150C Lead Temperature (soldering, 10SC) ...... cesses +300C 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 = 0.1} F, tested at 3.3V 410%; C1 = 0.047UF, C2-C4 = 0.33)F, tested at 5.0V 10%; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER | CONDITIONS MIN TYP MAX | UNITS DC CHARACTERISTICS (Vcc = +3.3V or +5V, Ta = +25C) Supply Current SHDN = Vcc, no load 0.3 1 mA Shutdown Supply Current SHDN = GND 1 10 pA LOGIC INPUTS Input Logic Threshold Low T_IN, SHDN 0.8 Vv . . ~ Voc = 3.3V 2.0 Input Logic Threshold High T_IN, SHDN Vv Voc = 5.0V 24 Transmitter Input Hysteresis 0.5 Vv Input Leakage Current T_IN, SHDN +0.01 +1 pA RECEIVER OUTPUTS Output Leakage Current R_OUT, receivers disabled +0.05 +10 HA Output Voltage Low louT = 1.6mA 0.4 Vv Output Voltage High louT = -1.0mA Voc- Voc - Vv 0.6 0.1 RECEIVER INPUTS Input Voltage Range -25 +25 Vv Voc = 3.3V 0.6 1.2 Input Threshold Low TA= +25C Vv Voc = 5.0V 0.8 1.5 . Voc = 3.3V 1.5 2.4 Input Threshold High TA= +25C Vv Voc = 5.0V 1.8 2.4 Input Hysteresis 0.5 Vv Input Resistance TA= +25C 3 5 7 kQ 2 MAXIM+15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver ELECTRICAL CHARACTERISTICS (continued) (Vcc = +3V to +5.5V, C1-C4 = 0.1pF, tested at 3.3V +10%; Ci = 0.047pF, C2-C4 = 0.33pF, tested at 5.0V +10%; Ta = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER | CONDITIONS MIN TYP MAX | UNITS TRANSMITTER OUTPUTS Output Voltage Swing All transmitter outputs loaded with 3kQ to ground +5 +5.4 Vv Output Resistance Vcc = V+ = V- = 0, transmitter output = +2V 300 10M Q Output Short-Circuit Current +60 mA Output Leakage Current Vcc = 0 or 8V to 5.5V, VouT = +12V, transmitters disabled +25 pA ESD PROTECTION Human Body Model 15 R_IN, TOUT IEC1000-4-2 Air Discharge +15 kV IEC1000-4-2 Contact Discharge +8 TIMING CHARACTERISTICS (Vcc = +3V to +5.5V, C1-C4 = 0.1pF, tested at 3.3V +10%; Ci = 0.047pF, C2-C4 = 0.33pF, tested at 5.0V +10%; Ta = TMIN to TMAX, unless otherwise noted. Typical values are at Ta = +25C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX | UNITS Maximum Data Rate RL = SkQ, CL 1000pF, 250 kbps one transmitter switching , tPHL Receiver input to receiver output 0.15 Receiver Propagation Dela , s pag y PL CL = 150pF 0.15 P Time to Exit Shutdown VouT = +3.7V, RLOAD at V+ = 3kQ 250 ys Transmitter Skew ItPHL - tPLH | (Note 2) 100 ns Receiver Skew ItPHL - tPLH | 50 ns Vcc = 3.3V, CL= 150pF to 6 30 TA= +25C, 1000pF Transition-Region Slew Rate RL = 3kQ to 7kQ, Vius measured from +3V | CL = 150pF to 4 30 to -3V or -3V to +3V | 2500pF Note 2: Transmitter skew is measured at the transmitter zero cross points. 3 MAXLM AG8EEXVWNMAX3385E +15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver Typical Operating Characteristics (Vcc = +3.3V, 250kbps data rate, 0.1pF capacitors, all transmitters loaded with 3kQ and C_, Ta = +25C, unless otherwise noted.) TRANSMITTER OUTPUT VOLTAGE OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE SLEW RATE vs. LOAD CAPACITANCE vs. LOAD CAPACITANCE 8 5 16 8 45 2 5 Vi 8 # T1 TRANSMITTING AT 250kbps # =, ae g (14 q 40 | Te TRANSMITTING AT 15.6kbps Z lu = 2 3 12 35 a [TH TRANSMITTING AT 250kops o = 40 250kbps z & = ' T2 TRANSMITTING AT 15.6kbps S 10 5B 420kbps E E 25 3 0 e 8 3 | = = 20 E a 6 a = a 5 (5 2 3 4 x 10 F -4 Vout. 5 5 FOR DATA RATES UP TO 250kbps -6 0 0 0 1000 2000 3000 4000 = 5000 0 1000 2000 = 3000 4000 5000 0 1000 2000 3000 +4000 += 5000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) Pin Description PIN NAME FUNCTION 2 Ci+ Positive terminal of the voltage-doubler charge-pump capacitor. 3 V+ +5.5V generated by the charge pump. 4 Ci- Negative terminal of the voltage-doubler charge-pump capacitor. 5 Ca+ Positive terminal of inverting charge-pump capacitor. 6 Ce2- Negative terminal of inverting charge-pump capacitor. 7 V- -5.5V generated by the charge pump. 8,17 T_OUT RS-232 Transmitter Outputs 9,16 R_IN RS-232 Receiver Inputs 12,15 R_OUT TTL/CMOS Receiver Outputs 13, 14 T_IN TTL/CMOS Transmitter Inputs 18 GND Ground 19 Vcc +3.0V to +5.5V Supply Voltage 20 SHDN Active-Low Shutdown-Control Input. Drive low to shut down transmitters and charge pump. 1,10, 11 N.C. No Connection. Not internally connected. 4 MAAXLM+15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver 0.1 uF Tt Vi Cit ce Ve - MAXKLAA MAX3385E +] TI + T C24 a _ T+] a Co. a ru . L 3k > an twee k T_ OUT Voc SHDN 2500pF 2 Zz Oo IH MINIMUM SLEW-RATE TEST CIRCUIT Ct+ Voc Ve 1 MAXUM! MAX3385E +] TI + T C2+ a _ T+] Tq Coto tT ru ;. 1 7k > ad SHDN T_ OUT k = Voc 2 Zz oO IH MAXIMUM SLEW-RATE TEST CIRCUIT Figure 1. Slew-Rate Test Circuits Detailed Description Dual Charge-Pump Voltage Converter The MAX3385Es internal power supply consists of a regulated dual charge pump that provides output volt- ages of +5.5V (doubling charge pump) and -5.5V (inverting charge pump), over the 3.0V to 5.5V Voc range. The charge pump operates in discontinuous mode; if the output voltages are less than 5.5V, the charge pump is enabled, and if the output voltages exceed 5.5V, the charge pump is disabled. Each charge pump requires a flying capacitor (C1, C2) anda reservoir capacitor (C3, C4) to generate the V+ and V- supplies (Figure 1). RS-232 Transmitters The transmitters are inverting level translators that con- vert CMOS-logic levels to +5.0V EIA/TIA-232 levels. The MAX3385E transmitters guarantee a 250kbps data rate with worst-case loads of 3kQ in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as LapLink). Transmitters can be paral- leled to drive multiple receivers or mice. Laplink is a trademark of Traveling Software. MAXLM The MAX3385Es transmitters are disabled and the out- puts are forced into a high-impedance state when the device is in shutdown (SHDN = GND). The MAX3385E permits the outouts to be driven up to 12V in shut- down. The transmitter inputs do not have pull-up resistors. Connect unused inputs to GND or Voc. RS-232 Receivers The receivers convert RS-232 signals to CMOS-logic output levels (Table 1). Shutdown Mode Supply current falls to less than 1pA in shutdown mode (SHDN = low). When shut down, the devices charge pumps are shut off, V+ is pulled down to Vcc, V- is pulled to ground, and the transmitter outputs are dis- abled (high impedance). The time required to exit shut- Table 1. Shutdown Truth Table SHDN T_OUT R_OUT 0 High-Z Active 1 Active Active AG8EEXVWNMAX3385E +15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver BVidiv | poemnnnrnnaatieanncenennimmencssamannmnnd SDH 0 po ar ovidiv | 0 Voc = 3.3V | TIOUT CICA = OF 40usidiv Figure 2. Transmitter Outputs Exiting Shutdown or Powering Up down is typically 100s, as shown in Figure 2. Connect SHDN to Vcc if the shutdown mode is not used. +15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electro- static discharges encountered during handling and assembly. The driver outputs and receiver inputs of the MAX3385E have extra protection against static electric- ity. Maxims 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 event, Maxim's E ver- sions keep working without latchup, whereas compet- ing RS-232 products can latch and must be powered down to remove 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) +15kV using the Human Body Model 2) +8kV using the contact-discharge method specified in IEC 1000-4-2 3) +15kV using IEC 1000-4-2s air-gap 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. Human Body Model Figure 3a shows the Human Body Model, and Figure 3b shows the current waveform it generates when dis- charged 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 1.5kQ resistor. IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and per- formance of finished equipment; it does not specifically refer to integrated circuits. The MAX3385E helps you design equipment that meets Level 4 (the highest level) of IEC 1000-4-2, without the need for additional ESD-pro- tection 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 with- stand voltage measured to IEC 1000-4-2 is generally lower than that measured using the Human Body Model. Figure 4a shows the IEC 1000-4-2 model, and Figure 4b 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 con- nects the probe to the device before the probe is ener- gized. Machine Model The Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resis- tance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. Of course, all pins require this protec- tion 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 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 0.1pF capaci- tors for 3.3V operation. For other supply voltages, refer to Table 2 for required capacitor values. Do not use val- Table 2. Required Minimum Capacitance Values Vec C1, Caypass C2, C3, C4 (V) (HF) (HF) 3.0 to 3.6 0.1 0.1 4.510 5.5 0.047 0.33 3.0 to 5.5 0.1 0.47 MAK+15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver Re Ro a _ CHARGE: CURRENT DISCHARGE Ip oe Ir os ING LIMIT RESISTOR RESISTANCE HIGH. mt DEVICE AMPERES VOLTAGE Cs STORAGE UNDER DC 100pF CAPACITOR | TEST 36.8% SOURCE 10% Ff- 0 0 ta. TIME t at }*_ to. CURRENT WAVEFORM Figure 3a. Human Body ESD Test Model Figure 3b. Human Body Model Current Waveform | A 100% --4------}----~----]-------. Ro Rp 90% | - 4 50M to 100M 3302 a CHARGE CURRENT DISCHARGE a LIMIT RESISTOR RESISTANCE 7 HIGH- DEVICE VOLTAGE Cg STORAGE UNDER DC 150pF CAPACITOR TEST SOURCE 10% F- tr = 0.7ns to 1ns >| < t ug OONS <_# 60ns p} Figure 4a. IEC 1000-4-2 ESD Test Model ues 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 C1s value. However, do not increase C1 without also increasing the values of C2, C3, C4, and Csypass 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 capaci- tors with a larger nominal value. The capacitors equiva- lent series resistance (ESR), which usually rises at low temperatures, influences the amount of ripple on V+ and V-. MAXLM Figure 4b. IEC 10000-4-2 ESD Generator Current Waveform Power-Supply Decoupling In most circumstances, a 0.1uUF Vcc bypass capacitor is adequate. In applications that are sensitive to power- supply noise, use a capacitor of the same value as charge-pump capacitor C1. Connect bypass capaci- tors as close to the IC as possible. Operation Down to 2.7V Transmitter outputs will meet EIA/TIA-562 levels of +3.7V with supply voltages as low as 2.7V. Transmitter Outputs when Exiting Shutdown Figure 2 shows two transmitter outputs when exiting shutdown mode. As they become active, the two trans- mitter outputs are shown going to opposite RS-232 lev- 7 AG8EEXVWNMAX3385E +15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver els (one transmitter input is high, the other is low). Each transmitter is loaded with 3kQ in parallel with 2500pF. The transmitter outputs display no ringing or undesir- able transients as they come out of shutdown. Note that the transmitters are enabled only when the magnitude of V- exceeds approximately -3V. High Data Rates The MAX3385E maintains the RS-232 +5.0V minimum transmitter output voltage even at high data rates. Figure 6 shows a transmitter loopback test circuit. Figure 7 shows a loopback test result at 120kbps, and Figure 8 shows the same test at 250kbps. For Figure 7, all transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 8, a single transmitter was driven at 250kbps, and all transmitters were loaded with an RS-232 receiver in parallel with 1000p F. Interconnection with 3V and 5V Logic The MAX3385E can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 3 for more information on possible combinations of interconnections. 0. 1pF T Voc a TH TH] a. T MAXIM = C24 MAX3385E V- C2 ES L C4 LT oe [tf ru \ ; san > E 1000pF iI -__" Voc SHDN* ILS Figure 6. Loopback Test Circuit THIN | 5V/div v4] BVidiv TOT Py: [| swidiv RIOUT UP Voc =3.3V Cio C4 =0.1pF 2us/div Figure 7. MAX3385E Loopback Test Result at 120kbps MAK+15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver TIIN TiOuT | RIOUT C1-C4=0.1nF 2us/div 5V/div 5Vidiv 5Vidiv Table 3. Logic-Family Compatibility with Various Supply Voltages SYSTEM Vcc SUPPLY POWER-SUPPLY VOLTAGE ow COMPATIBILITY (V) Compatible with all 3.3 3.3 CMOS families 5 5 Compatible with all TTL and CMOS families Compatible with ACT 5 33 and HCT CMOS, and , with AC, HC, or CD4000 CMOS Figure 8. MAX3385E Loopback Test Result at 250kbps MAXLM TRANSISTOR COUNT: 1129 Chip Information AG8EEXVWNMAX3385E +15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver Package Information INCHES MILLIMETERS INCHES [MILLIMETERS DiM| MIN | MAX | MIN | MAX A 5 L7 1 MIN MAX MIN MAX EEL ELT a{oues foo7s f1.73 1199 | [preea5 lazas | 607 | 633 | ML - - - - 0.239 10.249 6.07 6.33 |} 16L + E H SSOP.EPS 0.004 |0.008 | 0.09 |0.20 0.317 [0.328 | 8.07] 8.33] 24L 0.397 /|0.407 |10.07 | 10.33 | 28L +) 210.010 10.015 (025 1038 | Iplo.278|0.289 | 7.07| 7.33] 20L OO /oO/v|o SEE VARIATIONS C D E [0.205 [0.209 | 5.20 | 5.38 e |0.0256 BSC [0.65 BSC H L a 0.301 [0.311 | 7.65 | 7.90 0.025 |0.037 | 0.63 | 0.95 0 8 0 8 we| [at 7 , oop $F} Al NOTES: y 1, D&E DO NOT INCLUDE MOLD FLASH. MVLAM AL/VI 2. MOLD FLASH OR PROTRUSIONS NOT TO Ti EXCEED 15mm .006*) PACKAGE OUTLINE, SSOP, 5.3X.65mm APPROVAL DOCUMENT CONTROL NO. REV 3, CONTROLLING DIMENSION: MILLIMETER 21-0056 a4 10 MAK+15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver NOTES MAXLM "1 AG8EEXVWNMAX3385E +15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver NOTES 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. 12 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 1999 Maxim Integrated Products Printed USA MAXIMA is a registered trademark of Maxim Integrated Products.