MAX3386EEUP

19-1529; Rev 3; 4/01 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones The MAX3386E 3V-powered EIA/TIA-232 and V.28/V.24 is a communications interface with low power requirements, high data-rate capabilities, and enhanced electrostatic discharge (ESD) protection. The MAX3386E has two receivers and three transmitters. All RS-232 inputs and outputs are protected to ±25kV using the IEC 1000-4-2 Air-Gap Discharge method, ±8kV using the IEC 1000-4-2 Contact Discharge method, and ±15kV using the Human Body Model. A proprietary low-dropout transmitter output stage enables 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. The MAX3386E is capable of running at data rates up to 250kbps while maintaining RS-232 compliant output levels. The MAX3386E has a unique VL pin that allows interoperation in mixed-logic voltage systems. Both input and output logic levels are pin programmable through the VL pin. The MAX3386E is available in a space-saving TSSOP package. ♦ VL Pin for Compatibility with Mixed-Voltage Systems ♦ Enhanced ESD Protection on Rx Inputs and Tx Outputs ±15kV—Human Body Model ±25kV—IEC 1000-4-2, Air-Gap Discharge ±8kV—IEC 1000-4-2, Contact Discharge ♦ Low 300µA Supply Current ♦ Guaranteed 250kbps Data Rate ♦ 1µA Low-Power Shutdown ♦ Meets EIA/TIA-232 Specifications Down to 3.0V Ordering Information PART TEMP. RANGE 0°C to +70°C 20 TSSOP MAX3386EEUP -40°C to +85°C 20 TSSOP Typical Operating Circuit Applications Subnotebook/Palmtop Computers PDAs and PDA Cradles PIN-PACKAGE MAX3386ECUP +3.3V Cell Phone Data Cables Battery-Powered Equipment 20 CBYPASS C1 0.1µF Hand-Held Equipment Peripherals 1 C1+ 3 4 Pin Configuration C2 0.1µF 5 SHDN 12 19 VCC VL V+ 2 C3 0.1µF C1- MAX3386E C2+ V- 6 C2- 7 T1IN T1OUT 17 8 T2IN T2OUT 16 9 T3IN T3OUT 15 C4 0.1µF TOP VIEW C1+ 1 20 SHDN V+ 2 19 VCC C1- 3 18 GND C2+ 4 C2- 5 TTL/CMOS INPUTS 17 T1OUT MAX3386E V- 6 VL T1IN 7 14 R1IN T2IN 8 13 R2IN T3IN 9 12 VL R1IN 14 11 R1OUT 16 T2OUT 15 T3OUT TTL/CMOS OUTPUTS 5kΩ VL 10 R2OUT R2OUT 10 11 R1OUT RS-232 OUTPUTS RS-232 INPUTS R2IN 13 5kΩ GND 18 TSSOP ________________________________________________________________ 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 MAX3386E Features General Description MAX3386E 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones ABSOLUTE MAXIMUM RATINGS VCC to GND ..............................................................-0.3V to +6V VL to GND...................................................-0.3V to (VCC + 0.3V) V+ to GND ................................................................-0.3V to +7V V- to GND .................................................................+0.3V to -7V V+ + V-(Note 1) .............................................................. +13V Input Voltages T_IN, SHDN to GND ...........................................-0.3V to +6V R_IN to GND ..................................................................±25V Output Voltages T_OUT to GND............................................................±13.2V R_OUT.....................................................-0.3V to (VL + 0.3V) Short-Circuit Duration T_OUT to GND........................Continuous Continuous Power Dissipation (TA = +70°C) 20-Pin TSSOP (derate 7.0mW/°C above +70°C) .......559mW Operating Temperature Ranges MAX3386ECUP .................................................0°C to +70°C MAX3386EEUP ..............................................-40°C to +85°C Junction Temperature ......................................................+150°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. DC ELECTRICAL CHARACTERISTICS (VCC = VL = +3.0V to +5.5V; C1–C4 = 0.1µF, tested at +3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF, tested at +5.0V ±10%; TA = TMIN to TMAX; unless otherwise noted. Typical values are at VCC = VL = +3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1 10 µA 0.3 1 mA DC CHARACTERISTICS (VCC = +3.3V or +5V, TA = +25°C) Shutdown Supply Current SHDN = GND, all inputs at VCC or GND Supply Current SHDN = VCC, no load LOGIC INPUTS Input Logic Threshold Low Input Logic Threshold High T_IN, SHDN T_IN, SHDN VL = 3.3V or 5.0V 0.8 VL = 2.5V 0.6 VL = 5.0V 2.4 VL = 3.3V 2.0 VL = 2.5V 1.4 VL = 1.8V V V 0.9 Transmitter Input Hysteresis 0.5 V T_IN, SHDN ±0.01 ±1 µA Output Leakage Currents R_OUT, receivers disabled ±0.05 ±10 µA Output Voltage Low IOUT = 1.6mA 0.4 V Output Voltage High IOUT = -1mA Input Leakage Current RECEIVER OUTPUTS VL 0.6 VL 0.1 V RECEIVER INPUTS Input Voltage Range -25 Input Threshold Low TA = +25°C IOUT = -1mA Input Threshold High TA = +25°C 0.8 1.2 VL = 3.3V 0.6 1.5 1.8 2.4 VL = 3.3V 1.5 2.4 2 0.5 TA = +25°C 3 5 _______________________________________________________________________________________ V V VL = 5.0V Input Hysteresis Input Resistance +25 VL = 5.0V V V 7 kΩ 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones (VCC = VL = +3.0V to +5.5V; C1–C4 = 0.1µF, tested at +3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF, tested at +5.0V ±10%; TA = TMIN to TMAX; unless otherwise noted. Typical values are at VCC = VL = +3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS RECEIVER INPUTS TRANSMITTER OUTPUTS Output Voltage Swing All transmitter outputs loaded with 3kΩ to ground ±5 ±5.4 Output Resistance VCC = V+ = V- = 0, transmitter output = ±2V 300 10M Output Short-Circuit Current VT_OUT = 0 ±60 mA Output Leakage Current VT_OUT = ±12V, transmitters disabled; VCC = 0 or 3.0V to 5.5V ±25 µA V Ω ESD PROTECTION R_IN, T_OUT ESD Protection Human Body Model ±15 IEC 1000-4-2 Air-Gap Discharge method ±25 IEC 1000-4-2 Contact Discharge method ±8 kV TIMING CHARACTERISTICS (VCC = VL = +3V to +5.5V; C1–C4 = 0.1µF, tested at +3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF, tested at +5.0V ±10%; TA = TMIN to TMAX; unless otherwise noted. Typical values are at VCC = VL = +3.3V, TA = +25°C.) PARAMETER SYMBOL MIN RL = 3kΩ, CL = 1000pF, one transmitter switching Maximum Data Rate Receiver Propagation Delay CONDITIONS tPHL tPLH TYP MAX 250 kbps 0.15 Receiver input to receiver output, CL = 150pF UNITS µs 0.15 Receiver Output Enable Time 200 ns Receiver Output Disable Time 200 ns 100 µs 100 ns 50 ns Time to Exit Shutdown VT_OUT > 3.7V tPHL - tPLH (Note 2) tPHL - tPLH Transmitter Skew Receiver Skew Transition-Region Slew Rate VCC = 3.3V, TA = +25°C, RL = 3kΩ to 7kΩ, measured from +3V to -3V or -3V to +3V CL = 150pF to 1000pF 6 30 V/µs CL = 150pF to 2500pF 4 30 Note 2: Transmitter skew is measured at the transmitter zero crosspoint. _______________________________________________________________________________________ 3 MAX3386E DC ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = VL = +3.3V, TA = +25°C, unless otherwise noted.) TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE 2.5 MAX3386E toc 02 DATA RATE = 250kbps LOAD = 3kΩ IN PARALLEL WITH CL 14 12 SLEW RATE (V/µs) OUTPUT VOLTAGE (V) 5.0 SLEW RATE vs. LOAD CAPACITANCE 16 MAX3386E toc 01 7.5 0 -2.5 SLEW RATE 10 SLEW RATE + 8 6 4 -5.0 2 -7.5 0 1000 2000 3000 4000 0 5000 TRANSMITTER OUTPUT VOLTAGE vs. DATA RATE LOAD = 3kΩ, 1000pF ONE TRANSMITTER SWITCHING AT DATA RATE, OTHER TRANSMITTERS AT 1/8 DATA RATE 2.5 0 -2.5 4000 5000 LOAD = 3kΩ, ONE TRANSMITTER SWITCHING AT DATA RATE, OTHER 250kbps TRANSMITTERS AT 1/8 DATA RATE 50 40 120kbps 30 20 20kbps 10 -5.0 0 -7.5 0 50 100 150 DATA RATE (kbps) 4 3000 SUPPLY CURRENT vs. LOAD CAPACITANCE SUPPLY CURRENT (mA) 5.0 2000 60 MAX3386E toc 03 7.5 1000 LOAD CAPACITANCE (pF) LOAD CAPACITANCE (pF) MAX3386E toc 04 0 OUTPUT VOLTAGE (V) MAX3386E 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones 200 250 0 1000 2000 3000 4000 5000 LOAD CAPACITANCE (pF) _______________________________________________________________________________________ 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones PIN NAME FUNCTION 1 C1+ 2 V+ +5.5V Supply Generated by the Charge Pump 3 C1- Negative Terminal of the Voltage-Doubler Charge-Pump Capacitor 4 C2+ Positive Terminal of the Inverting Charge-Pump Capacitor 5 C2- Negative Terminal of the Inverting Charge-Pump Capacitor Positive Terminal of the Voltage-Doubler Charge-Pump Capacitor 6 V- 7 T1IN -5.5V Generated by the Charge Pump 8 T2IN 9 T3IN 10 R2OUT 11 R1OUT 12 VL 13 R2IN 14 R1IN 15 T3OUT 16 T2OUT 17 T1OUT 18 GND Ground 19 VCC +3.0V to +5.5V Supply Voltage 20 SHDN TTL/CMOS Transmitter Inputs TTL/CMOS Receiver Outputs. Swing between 0 and VL. Logic-Level Supply. All CMOS inputs and outputs are referenced to this supply. RS-232 Receiver Inputs RS-232 Transmitter Outputs Shutdown Input. 0 = shutdown, 1 = normal operation. _______________________________________________________________________________________ 5 MAX3386E Pin Description MAX3386E 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones Detailed Description Dual Charge-Pump Voltage Converter The MAX3386E’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), regardless of the input voltage (VCC) over a +3.0V to +5.5V range. The charge pumps operate in a discontinuous mode: if the output voltages are less than 5.5V, the charge pumps are enabled; if the output voltages exceed 5.5V, the charge pumps are disabled. Each charge pump requires a flying capacitor (C1, C2) and a reservoir capacitor (C3, C4) to generate the V+ and V- supplies. RS-232 Transmitters The transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The MAX3386E’s transmitters guarantee a 250kbps data rate with worst-case loads of 3kΩ in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as LapLink™). Transmitters can be paralleled to drive multiple receivers or mice. Figure 1 shows a complete system connection. POWERMANAGEMENT UNIT OR KEYBOARD CONTROLLER SHDN I/O CHIP POWER SUPPLY These RS-232 output stages are turned off (high impedance) when the device is in shutdown mode. When the power is off, the MAX3386E permits the outputs to be driven up to ±12V. The transmitter inputs do not have pull-up resistors. Connect unused inputs to GND or VL. RS-232 Receivers The receivers convert RS-232 signals to CMOS-logic output levels. The MAX3386E’s receivers have inverting three-state outputs, which depend on the shutdown state of the device. Shutdown Mode Supply current falls to less than 1µA when the MAX3386E is placed in shutdown mode (SHDN logic low). When shut down, the device’s charge pumps are turned off, V+ decays to VCC, V- is pulled to ground, and the transmitter outputs are disabled (high impedance). The time required to exit shutdown is typically 100µs, as shown in Figure 2. Connect SHDN to VCC if the shutdown mode is not used. In shutdown mode, the receiver outputs are high impedance (Table 1). Table 1. Shutdown Logic Truth Table SHDN TRANSMITTER OUTPUTS RECEIVER OUTPUTS CHARGE PUMP L High-Z High-Z Inactive H Active Active Active VL VCC MAX3386E I/O CHIP WITH UART 5V/div T2 2V/div RS-232 CPU T1 VCC = 3.3V C1–C4 = 0.1µF 50µs/div Figure 1. Interface Under Control of PMU Figure 2. Transmitter Outputs when Exiting Shutdown LapLink is a trademark of Traveling Software. 6 _______________________________________________________________________________________ 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones RC 1MΩ CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF MAX3386E VL Logic Supply Input Unlike other RS-232 interface devices where the receiver outputs swing between 0 and VCC, the MAX3386E features a separate logic supply input (VL) that sets VOH for the receiver outputs and sets thresholds for the transmitted and shutdown inputs. This feature allows a great deal of flexibility in interfacing to many different types of systems with different logic levels. Connect this input to the host logic supply (1.8V ≤ VL ≤ VCC). Also see the Typical PDA/Cell-Phone Application section. RD 1500Ω DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR ±25kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electrostatic discharges (ESDs) encountered during handling and assembly. The MAX3386E’s driver outputs and receiver inputs have extra protection against static electricity. Maxim has developed state-of-the-art structures to protect these pins against an ESD of ±25kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, Maxim’s “E” version devices keep working without latchup, whereas competing 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 Figure 3a. 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 3) ±25kV 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, methodology, and results. Human Body Model Figure 3a shows the Human Body Model, and Figure 3b 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 ICs. The MAX3386E helps you design equipment that meets Level 4 (the highest level) of IEC Figure 3b. Human Body Current Waveform 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 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 connects the probe to the device before the probe is energized. _______________________________________________________________________________________ 7 MAX3386E 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones RC 50MΩ to 100MΩ CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 150pF Machine Model RD 330Ω DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR 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. __________Applications Information Capacitor Selection The capacitor type used for C1–C4 is not critical for proper operation; polarized or nonpolarized capacitors can be used. The charge pump requires 0.1µF capacitors for 3.3V operation. For other supply voltages, see Table 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, and C4 to maintain the proper ratios (C1 to the other capacitors). Figure 4a. IEC 1000-4-2 ESD Test Model I 100% I PEAK 90% 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-. 10% Power-Supply Decoupling t R = 0.7ns to 1ns t 30ns 60ns Figure 4b. IEC 1000-4-2 ESD Generator Current Waveform Table 2. Minimum Required Capacitor Values 8 VCC (V) C1 (µF) C2, C3, C4 (µF) 3.0 to 3.6 0.1 0.1 4.5 to 5.5 0.047 0.33 3.0 to 5.5 0.22 1 In most circumstances, a 0.1µF bypass capacitor is adequate. In applications that are sensitive to powersupply noise, decouple VCC to ground with 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. Transmitter Outputs when Exiting Shutdown Figure 2 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 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. _______________________________________________________________________________________ 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones Interconnection with 3V and 5V Logic VCC 0.1µF VCC C1+ C1 C1- V+ C3 MAX3386E C2+ VC4 C2 C2- The MAX3386E can directly interface with various 5V logic families, including ACT and HCT CMOS. The logic voltage power-supply pin VL sets the output voltage level of the receivers and the input thresholds of the transmitters. T_ OUT T_ IN R_ IN R_ OUT Typical PDA/Cell-Phone Application The MAX3386E is designed with PDA applications in mind. Two transmitters and two receivers handle standard full-duplex communication protocol, while an extra transmitter allows a ring indicator (RI) signal to alert the UART on the PC. Without the ring indicator transmitter, solutions for these applications would require softwareintensive polling of the cradle inputs. The RI signal is generated when a PDA, cellular phone, or other “cradled” device is plugged into its cradle. This generates a logic-low signal to RI transmitter input, creating +6V at the ring indicate pin. The PC’s UART RI input is the only pin that can generate an interrupt from signals arriving through the RS-232 port. The interrupt routine for this UART will then service the RS-232 full-duplex communication between the PDA and the PC. As cell phone design becomes more like that of PDAs, cell phones will require similar docking ability and communication protocol. Cell phones operate on a single lithium-ion (Li+) battery and work with a power-supply voltage of +2.7V to +4V. The baseband logic coming from the phone connector can be as low as 1.8V at the transceivers. To prevent forward biasing of a device internal to the cell phone, the MAX3386E comes with a logic power-supply pin (VL) that limits the logic levels presented to the phone. The receiver outputs will sink to zero for low outputs, but will not exceed VL for logic highs. The input logic levels for the transmitters are also altered, scaled by the magnitude of the VL input. The device will work with V L as low as 1.8V before the charge-pump noise will begin to cause the transmitter outputs to oscillate. This is useful with cell phones and other power-efficient devices with core logic voltage levels that go as low as 1.8V. MAX3386E High Data Rates The MAX3386E maintains the RS-232 ±5.0V minimum transmitter output voltage even at high data rates. Figure 5 shows a transmitter loopback test circuit. Figure 6 shows a loopback test result at 120kbps, and Figure 7 shows the same test at 250kbps. For Figure 6, all transmitters were driven simultaneously at 120kbps into RS-232 loads in parallel with 1000pF. For Figure 7, a single transmitter was driven at 250kbps, and all transmitters were loaded with an RS-232 receiver in parallel with 1000pF. 5kΩ VCC SHDN 1000pF GND Figure 5. Loopback Test Circuit 5V/div T1IN 5V/div T1OUT 5V/div R1OUT VCC = +3.3V 2µs/div Figure 6. Loopback Test Results at 120kbps _______________________________________________________________________________________ 9 MAX3386E 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones T1IN 5V/div T1OUT 5V/div 5V/div R1OUT VCC = +3.3V 2µs/div Figure 7. Loopback Test Results at 250kbps Chip Information TRANSISTOR COUNT: 1267 10 ______________________________________________________________________________________ 3.0V, ±25kV ESD-Protected RS-232 Transceiver for PDAs and Cell Phones TSSOP.EPS MAX3386E Package Information 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. 11 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.