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19-1949; Rev 0; 1/01
15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver
________________General Description
The MAX3384E is a 3V-powered EIA/TIA-232 and V.28/V.24 communications interface with low power requirements, high data-rate capabilities, and enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to 15kV using IEC 1000-4-2 Air-Gap Discharge, 8kV using IEC 1000-4-2 Contact Discharge, and 15kV using the Human Body Model. The transceiver has 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 0.1F capacitors for operation from a +3.3V supply. Each device is guaranteed to run at data rates of 250kbps while maintaining RS-232 output levels. The MAX3384E has two receivers and two drivers. It features a 1A shutdown mode that reduces power consumption and extends battery life in portable systems. The MAX3384E is available in a space-saving SSOP package in either the commercial (0C to +70C) or extended temperature (-40C to +85C) range.
____________________________Features
o ESD Protection for RS-232 I/O Pins 15kV--Human Body Model 8kV--IEC 1000-4-2, Contact Discharge 15kV--IEC 1000-4-2, Air-Gap Discharge o Latchup Free o 300A Supply Current o 1A Low-Power Shutdown o 250kbps Guaranteed Data Rate o 250s Time to Exit Shutdown with 3k Load on V+ o 6V/s Guaranteed Slew Rate o Transmitter and Receiver Outputs High Impedance in Shutdown o Meets EIA/TIA-232 Specifications Down to 3.0V
MAX3384E
Ordering Information
PART MAX3384ECAP MAX3384ECWN MAX3384EEAP TEMP. RANGE 0C to +70C 0C to +70C -40C to +85C PIN-PACKAGE 20 SSOP 18 SO 20 SSOP
________________________Applications
Hand-Held Equipment Peripherals Printers Battery-Powered Equipment PDAs
+3.3V CBYPASS C1 0.1F
Typical Operating Circuit
C1+ C1-
VCC V+ C3* 0.1F
Pin Configurations
TOP VIEW
N.C. 1 C1+ 2 V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 T2OUT 8 R2IN 9 N.C. 10 20 SHDN 19 VCC 18 GND 17 T1OUT
TTL/CMOS INPUTS C2 0.1F
MAX3384E
C2+ C2T1IN T1OUT RS-232 OUTPUTS T2IN T2OUT VC4 0.1F
MAX3384E
16 R1IN 15 R1OUT 14 T1IN 13 T2IN 12 R2OUT 11 N.C.
TTL/CMOS OUTPUTS
R1OUT
R1IN 5k RS-232 INPUTS
R2OUT
R2IN 5k GND SHDN
SSOP Pin Configurations continued at end of data sheet.
* C3 CAN BE RETURNED TO EITHER 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 Integrated Products
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For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver MAX3384E
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V Continuous Power Dissipation (TA = +70C) V+ to GND (Note 1) ..................................................-0.3V to +7V 20-Pin SSOP (derate 8.00mW/C above +70C) ..........640mW V- to GND (Note 1) ...................................................+0.3V to -7V 18-Pin SO (derate 9.52mW/C above +70C)...............762mW V+ + |V-| (Note 1) .................................................................+13V Operating Temperature Ranges Input Voltages MAX3384ECAP ....................................................0C to +70C T_IN, SHDN to GND ..............................................-0.3V to +6V MAX3384ECWN ...................................................0C to +70C R_IN to GND .....................................................................25V MAX3384EEAP .................................................-40C to +85C Output Voltages Junction Temperature ........................................................150C T_OUT to GND...............................................................13.2V Storage Temperature Range .............................-65C to +150C R_OUT .....................................................-0.3V to (VCC + 0.3V) Lead Temperature (soldering, 10s) .................................+300C Maximum Current into T_OUT ........................................100mA Short-Circuit Duration, T_OUT to GND.......................Continuous 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
(V CC = +3V to +5.5V, for tests at 3.3V 10%, C1-C4 = 0.1F; for tests at +5V 10%, C1 = 0.047F, C2-C4 = 0.33F; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Supply Current Shutdown Supply Current LOGIC INPUTS Input Logic Threshold Low Input Logic Threshold High Transmitter Input Hysteresis Input Leakage Current RECEIVER OUTPUTS Output Leakage Current Output Voltage Low Output Voltage High RECEIVER INPUTS Input Voltage Range Input Threshold Low Input Threshold High Input Hysteresis Input Resistance 2 TA = +25C 3 TA = +25C TA = +25C VCC = +3.3V VCC = +5V VCC = +3.3V VCC = +5V -25 0.6 0.8 1.2 1.5 1.5 1.8 0.5 5 7 2.4 2.4 +25 V V V V k R_OUT, receivers disabled IOUT = 1.6mA IOUT = -1.0mA VCC 0.6 VCC 0.1 0.05 10 0.4 A V V T_IN, SHDN T_IN, SHDN T_IN, SHDN VCC = +3.3V VCC = +5V 2.0 2.4 0.5 0.01 1 0.8 V V V A SHDN = VCC, no load SHDN = GND CONDITIONS MIN TYP 0.3 1 MAX 1 10 UNITS mA A DC CHARACTERISTICS (VCC = +3.3V or +5V, TA = +25C)
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15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver
ELECTRICAL CHARACTERISTICS (continued)
(V CC = +3V to +5.5V, for tests at 3.3V 10%, C1-C4 = 0.1F; for tests at +5V 10%, C1 = 0.047F, C2-C4 = 0.33F; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER TRANSMITTER OUTPUTS Output Voltage Swing Output Resistance Output Short-Circuit Current Output Leakage Current ESD PROTECTION Human Body Model R_IN, T_OUT IEC1000-4-2 Air Discharge IEC1000-4-2 Contact Discharge 15 15 8 kV VCC = 0 or +3V to +5.5V, VOUT = 12V, transmitters disAll transmitter outputs loaded with 3k to ground VCC = 0, transmitter output = 2V 5 300 5.4 10M 60 25 V mA A CONDITIONS MIN TYP MAX UNITS
MAX3384E
TIMING CHARACTERISTICS
(VCC = +3V to +5.5V, for tests at 3.3V 10%, C1-C4 = 0.1F; for tests at +5V 10%, C1 = 0.047F, C2-C4 = 0.33F; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Maximum Data Rate Receiver Propagation Delay Receiver Output Enable Time Receiver Output Disable Time Time to Exit Shutdown Transmitter Skew Receiver Skew tPHL - tPLH| tPHL - tPLH| VCC = +3.3V, TA = +25C, RL = 3k to 7k, measured from +3V to -3V or -3V to +3V CL = 150pF to 1000pF CL = 150pF to 2500pF 6 4 tPHL tPLH SYMBOL CONDITIONS RL = 3k, CL = 1000pF, one transmitter switching Receiver input to receiver output, CL = 150pF SHDN from GND to VCC SHDN from VCC to GND VOUT +3.7V, RLOAD at V+ = 3k (Note 2) MIN 250 0.15 0.15 200 200 250 100 50 30 V/s 30 TYP MAX UNITS kbps s ns ns s ns ns
Transition-Region Slew Rate
Note 2: Transmitter skew is measured at the transmitter zero cross points.
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15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver MAX3384E
__________________________________________Typical Operating Characteristics
(VCC = +3.3V, 250kbps data rate, 0.1F capacitors, all transmitters loaded with 3k and CL, TA = +25C, unless otherwise noted.)
TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE
MAX3384E-01
SLEW RATE vs. LOAD CAPACITANCE
MAX3884E-02
OPERATING SUPPLY CURRENT vs. LOAD CAPACITANCE
40 SUPPLY CURRENT (mA) 35 250kbps 30 25 20 15 10 20kbps 120kbps T1 TRANSMITTING AT 250kbps T2 TRANSMITTING AT 15.6kbps
MAX3884E-03
TRANSMITTER OUTPUT VOLTAGE (V)
6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0 1000 2000
16 14 12 SLEW RATE (V/s) 10 8 6 4 +SLEW -SLEW
45
VOUT+ T1 TRANSMITTING AT 250kbps T2 TRANSMITTING AT 15.6kbps
VOUT-
2 FOR DATA RATES UP TO 250kbps 0
5 0 4000 5000 0 1000 2000 3000 4000 5000
3000
4000
5000
0
1000
2000
3000
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
LOAD CAPACITANCE (pF)
______________________________________________________________ Pin Description
PIN SO 1 2 3 4 5 6 7 8, 15 9, 14 10, 13 11, 12 16 17 18 SSOP 1, 10, 11 2 3 4 5 6 7 8, 17 9, 16 12, 15 13, 14 18 19 20 NAME N.C. C1+ V+ C1C2+ C2VT_OUT R_IN R_OUT T_IN GND VCC SHDN FUNCTION No Connection. Not internally connected. Positive terminal of the voltage-doubler charge-pump capacitor. +5.5V generated by the charge pump. Negative terminal of the voltage-doubler charge-pump capacitor. Positive terminal of inverting charge-pump capacitor. Negative terminal of inverting charge-pump capacitor. -5.5V generated by the charge pump. RS-232 Transmitter Outputs. High Z when SHDN is low. RS-232 Receiver Inputs TTL/CMOS Receiver Outputs. High Z when SHDN is low. TTL/CMOS Transmitter Inputs Ground +3.0V to +5.5V Supply Voltage. Connect a 0.1F capacitor to GND. Active-Low Shutdown-Control Input. Drive low to shut down transmitters, receivers and charge pumps.
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_______________________________________________________________________________________
15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver MAX3384E
VCC 0.1F VCC VCC 0.1F VCC
C1+ C1 C1C2+ C2 C2T_ IN
V+ C3 3k C1
C1+ C1C2+ C4 C2 C2T_ IN
V+ C3 3k
MAX3384E
V-
MAX3384E
VC4 T_ OUT
T_ OUT
R_ OUT
R_ IN
R_ OUT
R_ IN
5k VCC SHDN GND 3k 2500pF VCC SHDN GND
5k 7k 150pF
MINIMUM SLEW-RATE TEST CIRCUIT Figure 1. Slew-Rate Test Circuits
MAXIMUM SLEW-RATE TEST CIRCUIT
_______________Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3384E'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 Vsupplies (Figure 1).
The MAX3384E's transmitters are disabled and the outputs are forced into a high-impedance state when the device is in shutdown (SHDN = GND). The MAX3384E permits the outputs to be driven up to 12V in shutdown. The transmitter inputs do not have pullup resistors. Connect unused inputs to GND or VCC.
RS-232 Receivers
The receivers convert RS-232 signals to CMOS-logic output levels (Table 1). The receiver outputs are forced into a high-impedance state when the device is in shutdown (SHDN = GND). This allows a single UART to multiplex between different protocols.
RS-232 Transmitters
The transmitters are inverting level translators that convert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The MAX3384E transmitters guarantee a 250kbps data rate with worst-case loads of 3k in parallel with 1000pF, providing compatibility with PC-to-PC communication software (such as LapLinkTM). Transmitters can be paralleled to drive multiple receivers or mice.
Laplink is a trademark of Traveling Software.
Shutdown Mode
Supply current falls to less than 1A in shutdown mode (SHDN = low). When shut down, the device's charge
Table 1. Shutdown Truth Table
SHDN 0 1 T_OUT High-Z Active R_OUT High-Z Active 5
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15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver MAX3384E
5V/div 0 SHDN T2OUT
2V/div 0
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 1.5k resistor. IEC 1000-4-2 The IEC 1000-4-2 standard covers ESD testing and performance of finished equipment; it does not specifically refer to integrated circuits. The MAX3384E helps 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 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. 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. Of course, all pins require this protection during manufacturing, not just RS-232 inputs and outputs. Therefore, after PC board assembly, the Machine Model is less relevant to I/O ports.
VCC = 3.3V C1-C4 = 0.1F 40s/div
T1OUT
Figure 2. Transmitter Outputs Exiting Shutdown or Powering Up
pumps are shut off, V+ is pulled down to VCC, V- is pulled to ground, and the transmitter and receiver outputs are disabled (high impedance). The time required to exit shutdown 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 electrostatic discharges encountered during handling and assembly. The driver outputs and receiver inputs of the MAX3384E 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 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 3) 15kV using IEC 1000-4-2's 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.
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Applications Information
Capacitor Selection
The capacitor type used for C1-C4 is not critical for proper operation; polarized or nonpolarized capacitors
Table 2. Required Minimum Capacitance Values
VCC (V) 3.0 to 3.6 4.5 to 5.5 3.0 to 5.5 C1, CBYPASS (F) 0.1 0.047 0.1 C2, C3, C4 (F) 0.1 0.33 0.47
_______________________________________________________________________________________
15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver MAX3384E
RC 1M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 1500 DISCHARGE RESISTANCE DEVICE UNDER TEST
IP 100% 90% AMPERES 36.8% 10% 0 0 tRL TIME
Ir
PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE)
Cs 100pF
STORAGE CAPACITOR
tDL CURRENT WAVEFORM
Figure 3a. Human Body ESD Test Model
Figure 3b. Human Body Model Current Waveform
I 100% RC 50M to 100M CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE RD 330 DISCHARGE RESISTANCE DEVICE UNDER TEST 90%
Cs 150pF
STORAGE CAPACITOR
I PEAK
10% t r = 0.7ns to 1ns t 30ns 60ns
Figure 4a. IEC 1000-4-2 ESD Test Model
Figure 4b. IEC 1000-4-2 ESD Generator Current Waveform
can be used. The charge pump requires 0.1F capacitors for 3.3V operation. For other supply voltages, refer to 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 equiva-
lent 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 0.1F 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.
_______________________________________________________________________________________
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15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver MAX3384E
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 3k 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.
High Data Rates
The MAX3384E 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 1000pF.
VCC 0.1F
T1IN 5V/div
VCC C1+ C1 C1C2+ C2 C2V+ C3
5V/div
MAX3384E
T1OUT
VC4
R1OUT VCC = 3.3V C1-C4 = 0.1F 2s/div 5V/div
T_ IN
T_ OUT
R_ OUT
R_ IN
Figure 7. MAX3384E Loopback Test Result at 120kbps
5k VCC 1000pF
SHDN
GND
T1IN 5V/div
Figure 6. Loopback Test Circuit
T1OUT 5V/div
R1OUT
5V/div VCC = 3.3V C1-C4 = 0.1F 2s/div
Figure 8. MAX3384E Loopback Test Result at 250kbps
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_______________________________________________________________________________________
15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver
Table 3. Logic-Family Compatibility with Various Supply Voltages
SYSTEM POWER-SUPPLY VOLTAGE (V) 3.3 5 VCC SUPPLY VOLTAGE (V) 3.3 5 COMPATIBILITY
Pin Configurations (continued)
TOP VIEW
N.C. 1 C1+ 2 18 SHDN 17 VCC 16 GND 15 T1OUT
MAX3384E
Compatible with all CMOS families Compatible with all TTL and CMOS families Compatible with ACT and HCT CMOS, and with AC, HC, or CD4000 CMOS
V+ 3 C1- 4 C2+ 5 C2- 6 V- 7 T2OUT 8 R2IN 9
MAX3384E
14 R1IN 13 R1OUT 12 T1IN 11 T2IN 10 R2OUT
5
3.3
SO
Interconnection with 3V and 5V Logic
The MAX3384E can directly interface with various 5V logic families, including ACT and HCT CMOS. See Table 3 for more information on possible combinations of interconnections.
___________________Chip Information
TRANSISTOR COUNT: 1129 Process: BiCMOS
_______________________________________________________________________________________
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15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver MAX3384E
________________________________________________________Package Information
SSOP.EPS
10
______________________________________________________________________________________
15kV ESD-Protected, 3.0V to 5.5V, Low-Power, up to 250kbps, True RS-232 Transceiver
Package Information (continued)
SOICW.EPS
MAX3384E
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 (c) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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