19-1298; Rev 3a; 1/00 ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers ____________________________Features ♦ ESD Protection for RS-232 I/O Pins (MAX3222E/MAX3232E/MAX3241E) ±15kV—Human Body Model ±8kV—IEC 1000-4-2, Contact Discharge ±15kV—IEC 1000-4-2, Air-Gap Discharge ♦ ESD Protection for All Logic and Receiver I/O Pins (MAX3237E) ±15kV—Human Body Model ±8kV—IEC 1000-4-2, Contact Discharge ±15kV—IEC 1000-4-2, Air-Gap Discharge ♦ ESD Protection for Transmitter Output Pins (MAX3237E) ±15kV—Human Body Model ♦ Guaranteed Data Rate 250kbps (MAX3222E/MAX3232E/MAX3241E and MAX3237E, normal operation) 1Mbps (MAX3237E, MegaBaud operation) ♦ Latchup Free ♦ Low-Power Shutdown with Receivers Active 1µA (MAX3222E/MAX3241E) 10nA (MAX3237E) ♦ Flow-Through Pinout (MAX3237E) ♦ Guaranteed Mouse Driveability (MAX3241E) ♦ Meets EIA/TIA-232 Specifications Down to 3.0V ________________________Applications Notebooks, Subnotebooks, and Palmtop Computers Battery-Powered Equipment Cell-Phone Data Cables Smart Phones XDSL Modems Printers Cell Phones _______________Ordering Information PART TEMP. RANGE MAX3222ECUP 0°C to +70°C PIN-PACKAGE 20 TSSOP MAX3222ECAP 0°C to +70°C 20 SSOP Ordering Information continued at end of data sheet. ___________________________Selector Guide PART NO. OF DRIVERS/ RECEIVERS LOWPOWER SHUTDOWN GUARANTEED DATA RATE (kbps) MAX3222E MAX3232E 2/2 ✔ 250 2/2 — 250 MAX3237E (Normal) 5/3 ✔ 250 MAX3237E (MegaBaud) 5/3 ✔ 1M MAX3241E 3/5 ✔ 250 Pin Configurations appear at end of data sheet. Typical Operating Circuits appear at end of data sheet. MegaBaud is a trademark 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; and other patents pending. ________________________________________________________________ Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX3222E/MAX3232E/MAX3237E/MAX3241E† ________________General Description The MAX3222E/MAX3232E/MAX3237E/MAX3241E are 3V-powered EIA/TIA-232 and V.28/V.24 communications interfaces with low power requirements, high datarate capabilities, and enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to ±15kV using IEC 1000-4-2 AirGap Discharge, ±8kV using IEC 1000-4-2 Contact Discharge, and ±15kV using the Human Body Model. The MAX3237E’s logic and receiver I/O pins are protected to the above standards, while the transmitter output pins are protected to ±15kV using the Human Body Model. The transceivers have a proprietary low-dropout transmitter 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 0.1µF capacitors for operation from a +3.3V supply. Each device is guaranteed to run at data rates of 250kbps while maintaining RS232 output levels. The MAX3237E is guaranteed to run at data rates of 250kbps in the normal operating mode and 1Mbps in the MegaBaud™ operating mode while maintaining RS-232-compliant output levels. The MAX3222E/MAX3232E have two receivers and two drivers. The MAX3222E features a 1µA shutdown mode that reduces power consumption and extends battery life in portable systems. Its receivers can remain active in shutdown mode, allowing external devices such as modems to be monitored using only 1µA supply current. Both the MAX3222E and MAX3232E are pin, package, and functionally compatible with the industry-standard MAX242 and MAX232, respectively. The MAX3241E is a complete serial port (three drivers/five receivers) designed for notebook and subnotebook computers. The MAX3237E (five drivers/three receivers) is ideal for peripheral applications that require fast data transfer. Both devices feature a shutdown mode in which all receivers can remain active while using a supply current of only 1µA (MAX3241E) or 10nA (MAX3237E). The MAX3237E/MAX3241E have additional receiver outputs that always remain active. The MAX3222E and MAX3232E are available in spacesaving SO, SSOP, and TSSOP packages. The MAX3241E is available in SO and SSOP packages. The MAX3237E is available in an SSOP package. MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers 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, EN, SHDN, MBAUD to GND ........................-0.3V to +6V R_IN to GND .....................................................................±25V Output Voltages T_OUT to GND...............................................................±13.2V R_OUT, R_OUTB (MAX3241E)................-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 16-Pin Wide SO (derate 9.52mW/°C above +70°C) .....762mW 18-Pin Wide SO (derate 9.52mW/°C above +70°C) .....762mW 18-Pin PDIP (derate 11.11mW/°C above +70°C)..........889mW 20-Pin TSSOP (derate 7.0mW/°C above +70°C) ..........559mW 20-Pin SSOP (derate 8.00mW/°C above +70°C) ..........640mW 28-Pin SSOP (derate 9.52mW/°C above +70°C) ..........762mW 28-Pin Wide SO (derate 12.50mW/°C above +70°C) .............1W Operating Temperature Ranges MAX32_ _EC_ _ ...................................................0°C to +70°C MAX32_ _EE_ _.................................................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+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 = +3.0V to +5.5V, C1–C4 = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER CONDITIONS MIN TYP MAX MAX3222E, MAX3232E, MAX3241E 0.3 1 MAX3237E 0.5 2.0 UNITS DC CHARACTERISTICS (VCC = +3.3V or +5.0V, TA = +25°C) Supply Current Shutdown Supply Current SHDN = VCC, no load mA SHDN = GND 1 10 µA SHDN = R_IN = GND, T_IN = GND or VCC (MAX3237E) 10 300 nA 0.8 V LOGIC INPUTS Input Logic Low Input Logic High T_IN, EN, SHDN, MBAUD T_IN, EN, SHDN, MBAUD VCC = 3.3V 2.0 VCC = 5.0V 2.4 Transmitter Input Hysteresis Input Leakage Current V 0.5 T_IN, EN, SHDN MAX3222E, MAX3232E, MAX3241E T_IN, SHDN, MBAUD MAX3237E (Note 3) V ±0.01 ±1 9 18 ±0.05 ±10 µA RECEIVER OUTPUTS Output Leakage Current Output Voltage Low Output Voltage High R_OUT (MAX3222E/MAX3237E/MAX3241E), EN = VCC, receivers disabled IOUT = 1.6mA (MAX3222E/MAX3232E/MAX3241E) 0.4 IOUT = 1.0mA (MAX3237E) 0.4 VCC 0.6 IOUT = -1.0mA VCC 0.1 µA V V RECEIVER INPUTS Input Voltage Range Input Threshold Low 2 -25 TA = +25°C +25 VCC = 3.3V 0.6 1.1 VCC = 5.0V 0.8 1.5 _______________________________________________________________________________________ V V ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers (VCC = +3.0V to +5.5V, C1–C4 = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER CONDITIONS MIN TYP MAX VCC = 3.3V 1.5 2.4 VCC = 5.0V 2.0 2.4 UNITS RECEIVER INPUTS Input Threshold High TA = +25°C Input Hysteresis 0.5 Input Resistance TA = +25°C 3 5 V V 7 kΩ TRANSMITTER OUTPUTS Output Voltage Swing All transmitter outputs loaded with 3kΩ to ground ±5 ±5.4 Output Resistance VCC = 0, transmitter output = ±2V 300 50k Output Short-Circuit Current Output Leakage Current VCC = 0 or 3V to 5.5V, VOUT = ±12V, transmitters disabled (MAX3222E/MAX3232E/MAX3241E) V Ω ±60 mA ±25 µA MOUSE DRIVEABILITY (MAX3241E) Transmitter Output Voltage T1IN = T2IN = GND, T3IN = VCC, T3OUT loaded with 3kΩ to GND, T1OUT and T2OUT loaded with 2.5mA each ±5 V ESD PROTECTION R_IN, T_OUT T_IN, R_IN, R_OUT, EN, SHDN, MBAUD Human Body Model ±15 IEC 1000-4-2 Air-Gap Discharge (except MAX3237E) ±15 IEC 1000-4-2 Contact Discharge (except MAX3237E) ±8 MAX3237E Human Body Model ±15 IEC 1000-4-2 Air-Gap Discharge ±15 IEC 1000-4-2 Contact Discharge ±8 kV kV TIMING CHARACTERISTICS—MAX3222E/MAX3232E/MAX3241E (VCC = +3.0V to +5.5V, C1–C4 = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS RL = 3kΩ, CL = 1000pF, one transmitter switching Maximum Data Rate kbps Receiver input to receiver output, CL = 150pF 0.15 Receiver Output Enable Time Normal operation (except MAX3232E) 200 ns Receiver Output Disable Time Normal operation (except MAX3232E) 200 ns (Note 4) 100 ns 50 ns Receiver Propagation Delay tPHL 250 tPLH Transmitter Skew tPHL - tPLH Receiver Skew tPHL - tPLH Transition-Region Slew Rate VCC = 3.3V, TA = +25°C, RL = 3kΩ to 7kΩ, measured from +3V to -3V or -3V to +3V µs 0.15 CL = 150pF to 1000pF 6 30 CL = 150pF to 2500pF 4 30 V/µs Note 2: MAX3222E/MAX3232E/MAX3241E: C1–C4 = 0.1µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested at 5.0V ±10%. MAX3237E: C1–C4 = 0.1µF, tested at 3.3V ±5%; C1–C4 = 0.22µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested at 5.0V ±10%. Note 3: The MAX3237E logic inputs have an active positive feedback resistor. The input current goes to zero when the inputs are at the supply rails. Note 4: Transmitter skew is measured at the transmitter zero crosspoints. _______________________________________________________________________________________ 3 MAX3222E/MAX3232E/MAX3237E/MAX3241E ELECTRICAL CHARACTERISTICS (continued) TIMING CHARACTERISTICS—MAX3237E (VCC = +3.0V to +5.5V, C1–C4 = 0.1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER CONDITIONS Maximum Data Rate MIN RL = 3kΩ, CL = 1000pF, one transmitter switching, MBAUD = GND 250 VCC = 3.0V to 4.5V, RL = 3kΩ, CL = 250pF, one transmitter switching, MBAUD = VCC 1000 VCC = 4.5V to 5.5V, RL = 3kΩ, CL = 1000pF, one transmitter switching, MBAUD = VCC 1000 TYP MAX UNITS kbps tPHL 0.15 tPLH 0.15 Receiver Propagation Delay R_IN to R_OUT, CL = 150pF Receiver Output Enable Time Normal operation 2.6 µs Receiver Output Disable Time Normal operation 2.4 µs | tPHL - tPLH |, MBAUD = GND | tPHL - tPLH |, MBAUD = VCC | tPHL - tPLH | 100 ns 100 ns 50 ns Transmitter Skew Receiver Skew CL = 150pF to 1000pF VCC = 3.3V, RL = 3kΩ to 7kΩ, +3V to -3V or -3V to +3V, TA = +25°C Transition-Region Slew Rate µs MBAUD = GND 6 30 MBAUD = VCC 24 150 4 30 CL = 150pF to 2500pF, MBAUD = GND V/µs __________________________________________Typical Operating Characteristics (VCC = +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ and CL, TA = +25°C, unless otherwise noted.) -2 -3 -4 SLEW RATE (V/µs) 1 0 -1 -SLEW 10 +SLEW 8 6 4 VOUT- -5 -6 2000 3000 4000 LOAD CAPACITANCE (pF) 5000 35 250kbps 30 120kbps 25 20 20kbps 15 5 FOR DATA RATES UP TO 250kbps 1000 T1 TRANSMITTING AT 250kbps T2 TRANSMITTING AT 15.6kbps 40 10 2 0 0 0 4 14 12 T1 TRANSMITTING AT 250kbps T2 TRANSMITTING AT 15.6kbps 45 MAX3237E toc02 4 3 2 16 SUPPLY CURRENT (mA) VOUT+ MAX3237E toc01 6 5 MAX3222E/MAX3232E OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE MAX3222E/MAX3232E SLEW RATE vs. LOAD CAPACITANCE MAX3237E toc03 MAX3222E/MAX3232E TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE TRANSMITTER OUTPUT VOLTAGE (V) MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) 5000 0 1000 2000 3000 4000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 5000 ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers 8 6 4 4000 0 5000 1000 FOR DATA RATES UP TO 250kbps 1 TRANSMITTER 250kbps 4 TRANSMITTERS 15.6kbps ALL TRANSMITTERS LOADED WITH 3kΩ + CL 5.0 2Mbps 2000 1 TRANSMITTER AT FULL DATA RATE 4 TRANSMITTERS AT 1/16 DATA RATE 3kΩ + CL LOAD, EACH OUTPUT 0 -2.5 40 1 TRANSMITTER AT FULL DATA RATE 4 TRANSMITTERS AT 1/16 DATA RATE 3kΩ + CL LOAD EACH OUTPUT 500 1000 1500 2000 1000 1500 LOAD CAPACITANCE (pF) 0 50 250kbps 40 2000 120kbps 20kbps 30 20 1 TRANSMITTER AT 20kbps, 120kbps, 250kbps 4 TRANSMITTERS AT 15.6kbps ALL TRANSMITTERS LOADED WITH 3kΩ + CL 500 1000 1500 2000 LOAD CAPACITANCE (pF) 1000 1500 2000 2500 3000 MAX3237E TRANSMITTER SKEW vs. LOAD CAPACITANCE (MBAUD = VCC) 100 80 60 40 |tPLH - tPHL| 1 TRANSMITTER AT 500kbps 4 TRANSMITTERS AT 1/16 DATA RATE ALL TRANSMITTERS LOADED WITH 3kΩ + CL 20 0 0 500 LOAD CAPACITANCE (pF) 0 500 1 TRANSMITTER AT 250kbps 4 TRANSMITTERS 15.6kbps ALL TRANSMITTERS LOADED WITH 3kΩ + CL 0 10 0 4 2 MAX3237E SUPPLY CURRENT vs. LOAD CAPACITANCE WHEN TRANSMITTING DATA (MBAUD = GND) 30 SR+ 6 LOAD CAPACITANCE (pF) SUPPLY CURRENT (mA) -SLEW, 1Mbps +SLEW, 1Mbps -SLEW, 2Mbps +SLEW, 2Mbps 50 8 1.5Mbps 2Mbps -5.0 0 MAX3237E toc10 60 5000 SR- 2.5 300 4000 10 1Mbps 2500 3000 1.5Mbps TRANSMITTER SKEW (ns) 1500 2000 12 MAX3237E toc11 1000 1000 MAX3237E SLEW RATE vs. LOAD CAPACITANCE (MBAUD = GND) -7.5 500 70 0 0 5000 MAX3237E TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (MBAUD = VCC) VOUT- MAX3237E SLEW RATE vs. LOAD CAPACITANCE (MBAUD = VCC) SLEW RATE (V/µs) 4000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) 10 3000 1Mbps TRANSMITTER OUTPUT VOLTAGE (V) VOUT+ 0 20 2000 7.5 MAX3238E toc01 TRANSMITTER OUTPUT VOLTAGE (V) 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 20kbps 20 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 30 MAX3237E toc12 3000 SLEW RATE (V/µs) 2000 MAX3237E toc08 1000 120kbps 0 0 0 250kbps 40 10 2 VOUT- 1 TRANSMITTER AT 250kbps 2 TRANSMITTERS AT 15.6kbps 50 MAX3237E toc09 SLEW RATE (V/µs) 1 0 -1 -2 -3 -4 -5 -6 10 MAX3237E toc06 12 1 TRANSMITTER AT 250kbps 2 TRANSMITTERS AT 15.6kbps 60 SUPPLY CURRENT (mA) VOUT+ 4 3 2 14 MAX3237E toc05 6 5 MAX3241E OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE MAX3241E SLEW RATE vs. LOAD CAPACITANCE MAX3237E to04 TRANSMITTER OUTPUT VOLTAGE (V) MAX3241E TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 2500 3000 0 500 1000 1500 2000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 5 MAX3222E/MAX3232E/MAX3237E/MAX3241E Typical Operating Characteristics (continued) (VCC = +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ and CL, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ and CL, TA = +25°C, unless otherwise noted.) MAX3237E TRANSMITTER OUTPUT VOLTAGE vs. SUPPLY VOLTAGE (MBAUD = GND) 50 40 SUPPLY CURRENT (mA) VOUT+ MAX3237E toc14 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 MAX3237E SUPPLY CURRENT vs. SUPPLY VOLTAGE (MBAUD = GND) MAX3237E toc13 TRANSMITTER OUTPUT VOLTAGE (V) MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers 1 TRANSMITTER 250kbps 4 TRANSMITTERS 15.6kbps ALL TRANSMITTERS LOADED WITH 3kΩ +1000pF 30 20 10 VOUT- 1 TRANSMITTER AT 250kbps 4 TRANSMITTERS AT 15.6kbps ALL TRANSMITTERS LOADED WITH 3kΩ AND 1000pF 0 2.0 2.5 3.0 3.5 4.0 4.5 2.0 5.0 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) ______________________________________________________________Pin Description PIN MAX3222E 6 MAX3232E NAME FUNCTION MAX3237E MAX3241E SO/DIP TSSOP/ SSOP 1 — — 13* 23 EN 2 2 1 2 28 28 C1+ 3 3 2 3 27 27 V+ +5.5V Generated by the Charge Pump 4 4 3 4 25 24 C1- Negative Terminal of Voltage-Doubler Charge-Pump Capacitor 5 5 4 5 1 1 C2+ Positive Terminal of Inverting ChargePump Capacitor 6 6 5 6 3 2 C2- Negative Terminal of Inverting Charge-Pump Capacitor 7 7 6 7 4 3 V- 8, 15 8, 17 7, 14 8, 17 5, 6, 7, 10, 12 9, 10, 11 T_OUT SO/DIP TSSOP/ SSOP 1 Receiver Enable. Active low. Positive Terminal of Voltage-Doubler Charge-Pump Capacitor -5.5V Generated by the Charge Pump RS-232 Transmitter Outputs 9, 14 9, 16 8, 13 9, 16 8, 9, 11 4–8 R_IN 10, 13 10, 15 9, 12 12, 15 18, 20, 21 15–19 R_OUT RS-232 Receiver Inputs TTL/CMOS Receiver Outputs 11, 12 12, 13 10, 11 13, 14 17*, 19*, 22*, 23*, 24* 12, 13, 14 T_IN TTL/CMOS Transmitter Inputs 16 18 15 18 2 25 GND Ground _______________________________________________________________________________________ ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers PIN MAX3222E MAX3232E NAME FUNCTION MAX3237E MAX3241E SO/DIP TSSOP/ SSOP 19 16 19 26 26 VCC +3.0V to +5.5V Supply Voltage 18 20 — — 14* 22 SHDN Shutdown Control. Active low. — 11, 14 — 1, 10, 11, 20 — — N.C. — — — — 15* — MBAUD MegaBaud Control Input. Connect to GND for normal operation; connect to VCC for 1Mbps transmission rates. — — — — 16 20, 21 R_OUTB Noninverting Complementary Receiver Outputs. Always active. SO/DIP TSSOP/ SSOP 17 No Connection *These pins have an active positive feedback resistor internal to the MAX3237E, allowing unused inputs to be left unconnected. _______________Detailed Description Dual Charge-Pump Voltage Converter The MAX3222E/MAX3232E/MAX3237E/MAX3241E’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 VCC 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) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies (Figure 1). RS-232 Transmitters The transmitters are inverting level translators that convert TTL/CMOS-logic levels to ±5.0V EIA/TIA-232-compliant levels. The MAX3222E/MAX3232E/MAX3237E/MAX3241E transmitters 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 or mice. The MAX3222E/MAX3237E/MAX3241E’s transmitters are disabled and the outputs are forced into a high-imped- ance state when the device is in shutdown mode (SHDN = GND). The MAX3222E/MAX3232E/MAX3237E/MAX3241E permit the outputs to be driven up to ±12V in shutdown. The MAX3222E/MAX3232E/MAX3241E transmitter inputs do not have pull-up resistors. Connect unused inputs to GND or VCC. The MAX3237E transmitter inputs have a 400kΩ active positive feedback resistor, allowing unused inputs to be left unconnected. MAX3237E MegaBaud Operation For higher-speed serial communications, the MAX3237E features MegaBaud operation. In MegaBaud operating mode (MBAUD = V CC), the MAX3237E transmitters guarantee a 1Mbps data rate with worst-case loads of 3kΩ in parallel with 250pF for 3.0V < VCC < 4.5V. For 5V ±10% operation, the MAX3237E transmitters guarantee a 1Mbps data rate into worst-case loads of 3kΩ in parallel with 1000pF. RS-232 Receivers The receivers convert RS-232 signals to CMOS-logic output levels. The MAX3222E/MAX3237E/MAX3241E receivers have inverting three-state outputs. Drive EN high to place the receiver(s) into a high-impedance state. Receivers can be either active or inactive in shutdown (Table 1). LapLink is a trademark of Traveling Software. _______________________________________________________________________________________ 7 MAX3222E/MAX3232E/MAX3237E/MAX3241E _________________________________________________Pin Description (continued) MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers VCC VCC 0.1µF C1+ 0.1µF VCC C1+ V+ C1 C3 C1- C2 C2- V+ C1 C3 C2+ VCC C1- MAX3222E MAX3232E MAX3237E MAX3241E C2+ VC2 C4 C2T_ OUT T_ IN C4 T_ OUT R_ IN R_ OUT 5k GND V- T_ IN R_ IN R_ OUT MAX3222E MAX3232E MAX3237E MAX3241E 5k 3k 2500pF MINIMUM SLEW-RATE TEST CIRCUIT 150pF 7k GND MAXIMUM SLEW-RATE TEST CIRCUIT Figure 1. Slew-Rate Test Circuits The complementary outputs on the MAX3237E/MAX3241E (R_OUTB) are always active, regardless of the state of EN or SHDN. This allows the device to be used for ring indicator applications without forward biasing other devices connected to the receiver outputs. This is ideal for systems where VCC drops to 0 in shutdown to accommodate peripherals such as UARTs (Figure 2). MAX3222E/MAX3237E/MAX3241E Shutdown Mode Supply current falls to less than 1µA in shutdown mode (SHDN = low). The MAX3237E’s supply current falls to 10nA (typ) when all receiver inputs are in the invalid range (-0.3V < R_IN < +0.3). When shut down, the device’s charge pumps are shut off, V+ is pulled down to V CC , V- is pulled to ground, and the transmitter outputs are disabled (high impedance). The time required to recover from shutdown is typically 100µs, as shown in Figure 3. Connect SHDN to VCC if the shut- 8 down mode is not used. SHDN has no effect on R_OUT or R_OUTB (MAX3237E/MAX3241E). ±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated to protect against electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the Table 1. MAX3222E/MAX3237E/MAX3241E Shutdown and Enable Control Truth Table SHDN EN T_OUT R_OUT R_OUTB (MAX3237E/ MAX3241E) 0 0 High-Z Active Active 0 1 High-Z High-Z Active 1 0 Active Active Active 1 1 Active High-Z Active ______________________________________________________________________________________ ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers VCC VCC • ±8kV using the Contact Discharge method specified in IEC 1000-4-2 PREVIOUS RS-232 PROTECTION DIODE Rx • ±15kV using IEC 1000-4-2’s Air-Gap Discharge method For the MAX3237E, all logic and RS-232 I/O pins are characterized for protection to ±15kV per the Human Body Model. 5k UART Tx GND SHDN = GND 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. a) OLDER RS-232: POWERED-DOWN UART DRAWS CURRENT FROM ACTIVE RECEIVER OUTPUT IN SHUTDOWN. Human Body Model Figure 4a shows the Human Body Model, and Figure 4b 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. VCC TO µP latchup, whereas competing RS-232 products can latch and must be powered down to remove latchup. Furthermore, the MAX3237E logic I/O pins also have ±15kV ESD protection. Protecting the logic I/O pins to ±15kV makes the MAX3237E ideal for data cable applications. ESD protection can be tested in various ways; the transmitter outputs and receiver inputs for the MAX3222E/MAX3232E/MAX3241E are characterized for protection to the following limits: • ±15kV using the Human Body Model LOGIC TRANSITION DETECTOR MAX3237E/MAX3241E R1OUTB VCC PROTECTION DIODE Rx EN = VCC UART Tx GND R1IN R1OUT THREE-STATED T1IN 5V/div 0 SHDN T2OUT 5k T1OUT 2V/div 0 SHDN = GND b) NEW MAX3237E/MAX3241E: EN SHUTS DOWN RECEIVER OUTPUTS (EXCEPT FOR B OUTPUTS), SO NO CURRENT FLOWS TO UART IN SHUTDOWN. B OUTPUTS INDICATE RECEIVER ACTIVITY DURING SHUTDOWN WITH EN HIGH. Figure 2. Detection of RS-232 Activity when the UART and Interface are Shut Down; Comparison of MAX3237E/ MAX3241E (b) with Previous Transceivers (a) T1OUT VCC = 3.3V C1–C4 = 0.1µF 40µs/div Figure 3. Transmitter Outputs Recovering from Shutdown or Powering Up _______________________________________________________________________________________ 9 MAX3222E/MAX3232E/MAX3237E/MAX3241E MAX3222E/MAX3232E/MAX3237E/MAX3241E 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 event, Maxim’s E versions keep working without 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 MAX3222E/MAX3232E/ MAX3237E/MAX3241E 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 that measured using the Human Body Model. Figure 5a shows the IEC 1000-4-2 model, and Figure 5b shows the current waveform for the ±8kV IEC 1000-4-2 Level 4 ESD Contact Discharge test. RC 1MΩ CHARGE-CURRENT LIMIT RESISTOR The Air-Gap Discharge 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 manufacturing. 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. RD 1500Ω IP 100% 90% DISCHARGE RESISTANCE Ir PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES HIGHVOLTAGE DC SOURCE Cs 100pF STORAGE CAPACITOR DEVICE UNDER TEST 36.8% 10% 0 0 Figure 4a. Human Body ESD Test Model TIME tRL tDL CURRENT WAVEFORM Figure 4b. Human Body Model Current Waveform I 100% RC 50MΩ to 100MΩ CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 150pF RD 330Ω 90% DISCHARGE RESISTANCE STORAGE CAPACITOR I PEAK MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers DEVICE UNDER TEST 10% t r = 0.7ns to 1ns t 30ns 60ns Figure 5a. IEC 1000-4-2 ESD Test Model 10 Figure 5b. IEC 1000-4-2 ESD Generator Current Waveform ______________________________________________________________________________________ C1 (µF) C2, C3, C4 (µF) MAX3222E/MAX3232E/MAX3241E 3.0 to 3.6 0.1 0.1 4.5 to 5.5 0.047 0.33 3.0 to 5.5 0.1 0.47 MAX3237E 3.0 to 3.6 0.22 0.22 3.15 to 3.6 0.1 0.1 4.5 to 5.5 0.047 0.33 3.0 to 5.5 0.22 1.0 TRANSMITTER OUTPUT VOLTAGE (V) VCC (V) 6 5 4 VOUT+ VCC = 3.0V 3 2 VOUT+ 1 0 -1 -2 VCC -3 -4 VOUTVOUT- -5 -6 0 1 2 3 4 5 6 7 8 9 10 LOAD CURRENT PER TRANSMITTER (mA) Figure 6a. MAX3241E Transmitter Output Voltage vs. Load Current per Transmitter ___________Applications Information Transmitter Outputs when Recovering from Shutdown Capacitor Selection Figure 3 shows two transmitter outputs when recovering from 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 2500pF. 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. 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 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, 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. Operation Down to 2.7V Transmitter outputs will meet EIA/TIA-562 levels of ±3.7V with supply voltages as low as 2.7V. Mouse Driveability The MAX3241E has been specifically designed to power serial mice while operating from low-voltage power supplies. It has been tested with leading mouse brands from manufacturers such as Microsoft and Logitech. The MAX3241E successfully drove all serial mice tested and met their respective current and voltage requirements. Figure 6a shows the transmitter output voltages under increasing load current at 3.0V. Figure 6b shows a typical mouse connection using the MAX3241E. High Data Rates The MAX3222E/MAX3232E/MAX3237E/MAX3241E 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 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 1000pF. ______________________________________________________________________________________ 11 MAX3222E/MAX3232E/MAX3237E/MAX3241E Table 2. Required Minimum Capacitor Values MAX3222E-fig06a ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers VCC = 3V to 5.5V 28 C1 C2 C1+ 24 C1- 1 C2+ 2 CBYPASS 26 VCC V+ 27 C3 COMPUTER SERIAL PORT MAX3241E V- 3 C4 14 C2T1IN T1OUT 9 13 T2IN T2OUT 10 12 T3IN T3OUT 11 21 R1OUTB 20 R2OUTB 19 R1OUT 18 R2OUT 5k R2IN 5 17 R3OUT 5k R3IN 6 16 R4OUT 5k R4IN 7 15 R5OUT 23 EN +V +V VCC -V GND Tx R1IN 4 MOUSE 5k R5IN 8 5k SHDN GND 25 22 VCC Figure 6b. Mouse Driver Test Circuit The MAX3237E maintains the RS-232 ±5.0V minimum transmitter output voltage at data rates up to 1Mbps. Figure 10 shows a loopback test result at 1Mbps with MBAUD = VCC. For Figure 10, all transmitters were loaded with an RS-232 receiver in parallel with 250pF. 12 Interconnection with 3V and 5V Logic The MAX3222E/MAX3232E/MAX3237E/MAX3241E can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 3 for more information on possible combinations of interconnections. ______________________________________________________________________________________ ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers 5V/div T1IN SYSTEM POWER-SUPPLY VOLTAGE (V) VCC SUPPLY VOLTAGE (V) 3.3 3.3 5 5 Compatible with all TTL and CMOS families 3.3 Compatible with ACT and HCT CMOS, and with AC, HC, or CD4000 CMOS COMPATIBILITY 5V/div 5 Compatible with all CMOS families T1OUT R1OUT 5V/div VCC = 3.3V C1–C4 = 0.1µF 2µs/div Figure 8. MAX3241E Loopback Test Result at 120kbps T1IN 5V/div T1OUT 5V/div VCC 0.1µF VCC C1+ V+ C3 C1 C1C2+ C2 C2- 5V/div R1OUT MAX3222E MAX3232E MAX3237E MAX3241E VCC = 3.3V, C1–C4 = 0.1µF VC4 2µs/div Figure 9. MAX3241E Loopback Test Result at 250kbps T_ OUT T_ IN R_ IN R_ OUT 5k +5V 1000pF T_IN 0 +5V GND -5V +5V Figure 7. Loopback Test Circuit T_OUT 5kΩ + 250pF 0 VCC = 3.3V C1–C4 = 0.1µF R_OUT 0 400ns/div Figure 10. MAX3237E Loopback Test Result at 1000kbps (MBAUD = VCC) ______________________________________________________________________________________ 13 MAX3222E/MAX3232E/MAX3237E/MAX3241E Table 3. Logic-Family Compatibility with Various Supply Voltages ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers MAX3222E/MAX3232E/MAX3237E/MAX3241E Pin Configurations TOP VIEW EN 1 18 SHDN EN 1 20 SHDN N.C. 1 20 N.C. C1+ 2 17 VCC C1+ 2 19 VCC C1+ 2 19 VCC V+ 3 16 GND V+ 3 18 GND V+ 3 18 GND 15 T1OUT C1- 4 C2+ 5 C2- MAX3222E 6 C1- 4 14 R1IN C2+ 5 13 R1OUT C2- 6 MAX3222E 17 T1OUT C1- 4 16 R1IN C2+ 5 15 R1OUT C2- 6 17 T1OUT MAX3232E 16 R1IN 15 R1OUT V- 7 12 T1IN V- 7 14 N.C. V- 7 T2OUT 8 11 T2IN T2OUT 8 13 T1IN T2OUT 8 R2IN 9 10 R2OUT R2IN 9 12 T2IN R2IN 9 12 R2OUT 11 N.C. N.C. 10 11 N.C. R2OUT 10 14 T1IN 13 T2IN SO/DIP TSSOP TSSOP/SSOP C1+ 1 16 VCC C2+ 1 28 C1+ C2+ 1 28 C1+ V+ 2 15 GND GND 2 27 V+ C2- 2 27 V+ C2- 3 26 VCC V- 3 26 VCC V- 4 25 C1- R1IN 4 25 GND T1OUT 5 24 T1IN R2IN 5 C1- 3 C2+ 4 14 T1OUT MAX3232E C2- 5 13 R1IN 12 R1OUT MAX3237E 11 T1IN T2OUT 6 23 T2IN R3IN 6 23 EN T2OUT 7 10 T2IN T3OUT 7 22 T3IN R4IN 7 22 SHDN R1IN 8 21 R1OUT R5IN 8 21 R1OUTB R2IN 9 20 R2OUT T1OUT 9 20 R2OUTB 19 T4IN T2OUT 10 19 R1OUT 18 R3OUT 9 R2OUT R2IN 8 SSOP/SO/DIP T4OUT 10 T3OUT 11 18 R2OUT 17 T5IN T3IN 12 17 R3OUT EN 13 16 R1OUTB T2IN 13 16 R4OUT SHDN 14 15 MBAUD T1IN 14 15 R5OUT R3IN 11 T5OUT 12 SSOP 14 24 C1- MAX3241E V- 6 SSOP/SO ______________________________________________________________________________________ ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers +3.3V +3.3V 17 CBYPASS C1 0.1µF 2 C1+ 4 5 C2 0.1µF 6 V+ 3 C1- MAX3222E C2+ V- C3* 0.1µF C1 0.1µF C4 0.1µF C2 0.1µF 7 C2- 12 T1IN 10 R2OUT 1 C2+ MAX3232E SHDN 6 C4 0.1µF RS-232 OUTPUTS T2OUT 7 R1IN 13 5k 9 R2OUT RS-232 INPUTS R2IN 8 5k GND 16 V- T1OUT 14 TTL/CMOS OUTPUTS R2IN 9 EN C3* 0.1µF C2- 12 R1OUT RS-232 INPUTS 5k 2 C1- 10 T2IN R1IN 14 TTL/CMOS OUTPUTS 5 V+ TTL/CMOS INPUTS T2OUT 8 13 R1OUT 3 VCC 11 T1IN RS-232 OUTPUTS TTL/CMOS INPUTS 1 C1+ 4 T1OUT 15 11 T2IN 16 CBYPASS VCC 5k 18 GND 15 *C3 CAN BE RETURNED TO EITHER VCC OR GROUND. NOTE: PIN NUMBERS REFER TO SO/DIP PACKAGES. SEE TABLE 2 FOR CAPACITOR SELECTION. ______________________________________________________________________________________ 15 MAX3222E/MAX3232E/MAX3237E/MAX3241E __________________________________________________Typical Operating Circuits MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers _____________________________________Typical Operating Circuits (continued) +3.3V +3.3V CBYPASS C1 0.1µF 28 C1+ TTL/CMOS INPUTS VCC 27 V+ 2 C2+ MAX3241E V- 28 C1+ C3* 0.1µF 24 C11 C2 0.1µF CBYPASS 26 C2- 14 T1IN T1OUT 9 13 T2IN T2OUT 10 12 T3IN T3OUT 11 27 V+ C3* 0.1µF 25 C11 0.1µF 3 C2+ 23 T2IN RS-232 OUTPUTS LOGIC INPUTS MAX3237E V- 4 0.1µF C2- 24 T1IN 21 R1OUTB VCC 0.1µF 3 C4 0.1µF 26 22 T3IN 19 T4IN T1 T2 T3 T4 T1OUT 5 T2OUT 6 T3OUT 7 RS-232 OUTPUTS T4OUT 10 20 R2OUTB 17 T5IN 19 R1OUT R2IN 18 R2OUT T5OUT 12 16 R1OUTB 5k 5 21 R1OUT TTL/CMOS OUTPUTS T5 R1IN 4 5k R1IN 8 R1 5k 17 R3OUT R3IN 6 5k RS-232 INPUTS LOGIC OUTPUTS 20 R2OUT R2IN R2 9 5k 16 R4OUT R4IN 7 18 R3OUT R3IN 11 R3 5k 15 R5OUT 5k R5IN 8 5k MBAUD 13 EN 23 EN GND SHDN 22 GND SHDN 2 25 *C3 CAN BE RETURNED TO EITHER VCC OR GROUND. 16 ______________________________________________________________________________________ 15 14 RS-232 INPUTS ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers PART TEMP. RANGE MAX3222ECWN 0°C to +70°C 18 Wide SO MAX3222ECPN 0°C to +70°C 18 Plastic DIP MAX3222EC/D 0°C to +70°C Dice* MAX3222EEUP -40°C to +85°C 20 TSSOP MAX3222EEAP -40°C to +85°C 20 SSOP MAX3222EEWN -40°C to +85°C 18 Wide SO MAX3222EEPN -40°C to +85°C MAX3232ECUP 0°C to +70°C 20 TSSOP MAX3232ECAE MAX3232ECWE MAX3232ECPE 0°C to +70°C 0°C to +70°C 0°C to +70°C 16 SSOP 16 Wide SO 16 Plastic DIP MAX3232EEUP MAX3232EEAE MAX3232EEWE MAX3232EEPE MAX3237ECAI -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -0°C to +70°C -40°C to +85°C 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C 20 TSSOP 16 SSOP 16 Wide SO 16 Plastic DIP 28 SSOP 28 SSOP 28 SSOP 28 Wide SO 28 SSOP 28 Wide SO MAX3237EEAI MAX3241ECAI MAX3241ECWI MAX3241EEAI MAX3241EEWI PIN-PACKAGE ___________________ Chip Information TRANSISTOR COUNTS: MAX3222E/MAX3232E: 1129 MAX3237E: 2110 MAX3241E: 1335 18 Plastic DIP *Dice are tested at TA = +25°C, DC parameters only. ______________________________________________________________________________________ 17 MAX3222E/MAX3232E/MAX3237E/MAX3241E __Ordering Information (continued) ________________________________________________________Package Information TSSOP.EPS MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers 18 ______________________________________________________________________________________ ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers SSOP.EPS ______________________________________________________________________________________ 19 MAX3222E/MAX3232E/MAX3237E/MAX3241E ___________________________________________Package Information (continued) MAX3222E/MAX3232E/MAX3237E/MAX3241E ±15kV ESD-Protected, Down to 10nA, 3.0V to 5.5V, Up to 1Mbps, True RS-232 Transceivers 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. 20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.