19-0742; Rev 0; 1/07 Half-Duplex RS-485/RS-422 Transceivers in µDFN The MAX13485E/MAX13486E +5V, half-duplex, ±15kV ESD-protected RS-485 transceivers feature one driver and one receiver. These devices include fail-safe circuitry, guaranteeing a logic-high receiver output when receiver inputs are open or shorted. The receiver outputs a logichigh if all transmitters on a terminated bus are disabled (high impedance). The MAX13485E/MAX13486E include a hot-swap capability to eliminate false transitions on the bus during power-up or live-insertion. The MAX13485E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission up to 500kbps. The MAX13486E driver slew rate is not limited, allowing transmit speeds up to 16Mbps. The MAX13485E/MAX13486E feature a 1/4-unit load receiver input impedance, allowing up to 128 transceivers on the bus. These devices are intended for half-duplex communications. All driver outputs are protected to ±15kV ESD using the Human Body Model. The MAX13485E/ MAX13486E are available in 8-pin SO and space-saving 8-pin µDFN packages. The devices operate over the extended -40°C to +85°C temperature range. Applications Utility Meters Industrial Controls Features ♦ +5V Operation ♦ True Fail-Safe Receiver While Maintaining EIA/TIA-485 Compatibility ♦ Hot-Swappable for Telecom Applications ♦ Enhanced Slew-Rate Limiting Facilitates ErrorFree Data Transmission (MAX13485E) ♦ High-Speed Version (MAX13488E) Allows for Transmission Speeds Up to 16Mbps ♦ Extended ESD Protection for RS-485/RS-422 I/O Pins ±15kV Using Human Body Model ♦ 1/4 Unit Load, Allowing Up to 128 Transceivers on the Bus ♦ Available in Space-Saving 8-Pin µDFN or Industry Standard 8-Pin SO Packages Ordering Information/ Selector Guide PART PINPACKAGE SLEW-RATE LIMITED PKG CODE MAX13485EELA+T 8 µDFN Yes L822-1 MAX13485EESA+ 8 SO Yes S8-2 MAX13486EELA+T 8 µDFN No L822-1 MAX13486EESA+ 8 SO No S8-2 +Denotes a lead-free package. Note: All devices are specified over the -40°C to +85°C operating temperature range. Industrial Motor Drives Automated HVAC Systems Pin Configurations TOP VIEW VCC B A GND 8 7 6 5 MAX13485E MAX13486E DE + 0.1µF 1 2 RO 3 RE DE 4 RO DI + RO MAX13485E MAX13486E 1 8 R 2 7 B DE 3 6 A 5 GND D 8 R 7 DE 3 4 DI 6 5 D VCC D B Rt A R SO DI B Rt A VCC RE DI 4 + 2 RE DFN 1 RO GND RE SO ________________________________________________________________ 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 MAX13485E/MAX13486E General Description MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) VCC ........................................................................................+6V DE, RE, DI.................................................................-0.3V to +6V A, B ..............................................................................-8V to 13V Short-Circuit Duration (RO, A, B) to GND ..................Continuous Continuous Power Dissipation (TA = +70°C) 8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW 8-Pin µDFN (derate 4.8mW/°C above +70°C) ..........380.6mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DRIVER Differential Driver Output VOD RDIFF = 100Ω, Figure 1 2.0 RDIFF = 54Ω, Figure 1 1.5 VCC V No load VCC 0.2 V 3 V 0.2 V Change in Magnitude of Differential Output Voltage ∆VOD RDIFF = 100Ω or 54Ω, Figure 1 (Note 3) Driver Common-Mode Output Voltage VOC RDIFF = 100Ω or 54Ω, Figure 1 Change in Magnitude of Common-Mode Voltage ∆VOC RDIFF = 100Ω or 54Ω, Figure 1 (Note 3) VCC /2 Input-High Voltage VIH DI, DE, RE Input-Low Voltage VIL DI, DE, RE 0.8 V Input Current IIN DI, DE, RE ±1 µA Driver Short-Circuit Output Current (Note 4) IOSD Driver Short-Circuit Foldback Output Current Note 3) IOSDF 2.0 V 0V < VOUT < +12V +50 +250 -7V < VOUT < 0V -250 -50 (VCC - 1V) < VOUT < +12V 20 -7V < VOUT < 0V -20 mA mA RECEIVER Input Current (A and B) IA, B DE = GND, VCC = GND or +5V Receiver-Differential-Threshold Voltage VTH -7V < VCM < +12V Receiver Input Hysteresis ∆VTH VA + VB = 0V Output-High Voltage 2 VOH IO = -1.6mA, VA - VB > VTH VIN = +12V VIN = -7V 250 -200 -200 -50 25 VCC 1.5 _______________________________________________________________________________________ µA mV mV V Half-Duplex RS-485/RS-422 Transceivers in µDFN ELECTRICAL CHARACTERISTICS (continued) MAX UNITS Output-Low Voltage PARAMETER SYMBOL VOL IO = 1mA, VA - VB < -VTH CONDITIONS MIN TYP 0.4 V Tri-State Output Current at Receiver IOZR 0V < VO < VCC ±1 µA Receiver Input Resistance RIN -7V < VCM < +12V 48 Receiver-Output Short-Circuit Current IOSR 0V < VRO < VCC ±7 ±95 4.75 kΩ mA POWER SUPPLY Supply Voltage VCC Supply Current ICC Shutdown Supply Current ISHDN 5.25 V DE = 1, RE = 0, no load 4.5 mA DE = 0, RE = 1 10 µA ESD PROTECTION ESD Protection (A, B) ESD Protection (All Other Pins) Air Gap Discharge IEC61000-4-2 (MAX13485E) ±15 Human Body Model ±15 Human Body Model ±2 kV kV SWITCHING CHARACTERISTICS—MAX13485E (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DRIVER Driver Propagation Delay Driver-Differential Output Rise or Fall Time Driver-Differential Output Skew |tDPLH - tDPHL| tDPLH tDPHL tHL tLH tDSKEW RDIFF = 54Ω, CL = 50pF, Figures 2 and 3 RDIFF = 54Ω, CL = 50pF, Figures 2 and 3 200 1000 200 1000 250 900 250 900 RDIFF = 54Ω, CL = 50pF, Figures 2 and 3 Maximum Data Rate 140 500 ns ns ns kbps Driver Enable to Output High tDZH Figures 4 and 5 2500 ns Driver Enable to Output Low tDZL Figures 4 and 5 2500 ns Driver Disable Time from High tDHZ Figures 4 and 5 100 ns Driver Disable Time from Low tDLZ Figures 4 and 5 100 ns Driver Enable from Shutdown to Output High tDZH(SHDN) Figures 4 and 5 5500 ns Driver Enable from Shutdown to Output Low tDZL(SHDN) Figures 4 and 5 5500 ns 700 ns Time to Shutdown tSHDN 50 340 RECEIVER Receiver Propagation Delay Receiver Output Skew Maximum Data Rate tRPLH tRPHL tRSKEW 80 CL = 15pF, Figures 6 and 7 80 CL = 15pF, Figure 7 13 500 ns ns kbps _______________________________________________________________________________________ 3 MAX13485E/MAX13486E (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Notes 1, 2) MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN SWITCHING CHARACTERISTICS—MAX13485E (continued) (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Receiver Enable to Output High tRZH Figure 8 50 ns Receiver Enable to Output Low tRZL Figure 8 50 ns Receiver Disable Time from High tRHZ Figure 8 50 ns Receiver Disable Time from Low tRLZ Figure 8 50 ns Receiver Enable from Shutdown to Output High tRZH(SHDN) Figure 8 2200 ns Receiver Enable from Shutdown to Output Low tRZL(SHDN) Figure 8 2200 ns 700 ns Time to Shutdown tSHDN 50 340 SWITCHING CHARACTERISTICS—MAX13486E (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DRIVER Driver Propagation Delay Driver Differential Output Rise or Fall Time Differential Driver Output Skew |tDPLH - tDPHL| tDPLH tDPHL tHL tLH tDSKEW 50 RDIFF = 54Ω, CL = 50pF, Figures 2 and 3 50 15 RDIFF = 54Ω, CL = 50pF, Figures 2 and 3 15 RDIFF = 54Ω, CL = 50pF, Figures 2 and 3 Maximum Data Rate 8 16 ns ns ns Mbps Driver Enable to Output High tDZH Figures 4 and 5 50 ns Driver Enable to Output Low tDZL Figures 4 and 5 50 ns Driver Disable Time from High tDHZ Figures 4 and 5 50 ns Driver Disable Time from Low tDLZ Figures 4 and 5 50 ns Driver Enable from Shutdown to Output High tDZH(SHDN) Figures 4 and 5 2200 ns Driver Enable from Shutdown to Output Low tDZL(SHDN) Figures 4 and 5 2200 ns 700 ns Time to Shutdown tSHDN 50 340 RECEIVER Receiver Propagation Delay Receiver Output Skew Maximum Data Rate 4 tRPLH tRPHL tRSKEW 80 CL = 15pF, Figures 6 and 7 80 CL = 15pF, Figure 7 13 16 _______________________________________________________________________________________ ns ns Mbps Half-Duplex RS-485/RS-422 Transceivers in µDFN (VCC = +5V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Receiver Enable to Output High tRZH Figure 8 50 ns Receiver Enable to Output Low tRZL Figure 8 50 ns Receiver Disable Time from High tRHZ Figure 8 50 ns Receiver Disable Time from Low tRLZ Figure 8 50 ns Receiver Enable from Shutdown to Output High tRZH(SHDN) Figure 8 2200 ns Receiver Enable from Shutdown to Output Low tRZL(SHDN) Figure 8 2200 ns 700 ns Time to Shutdown tSHDN 50 340 Note 1: µDFN devices production tested at +25°C. Overtemperature limits are generated by design. Note 2: All currents into the device are positive. All currents out of the device are negative. All voltages referred to device ground, unless otherwise noted. Note 3: ∆VOD and ∆VOC are the changes in VOD and VOC when the DI input changes states. Note 4: The short-circuit output current applied to peak current just prior to foldback current limiting. The short-circuit foldback output current applies during current limiting to allow a recovery from bus contention. Typical Operating Characteristics (VCC = +5V, TA = +25°C, unless otherwise noted.) OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE 3.6 3.4 28 21 14 7 3.2 -40 -15 10 35 TEMPERATURE (°C) 60 85 50 40 30 20 10 0 0 3.0 60 MAX13485-86E toc03 35 OUTPUT CURRENT (mA) SUPPLY CURRENT (mA) 3.8 OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE MAX13485-86E toc02 NO LOAD OUTPUT CURRENT (mA) 4.0 MAX13485-86E toc01 SUPPLY CURRENT vs. TEMPERATURE 0 1 2 3 OUTPUT HIGH VOLTAGE (V) 4 5 0 1 2 3 4 5 OUTPUT LOW VOLTAGE (V) _______________________________________________________________________________________ 5 MAX13485E/MAX13486E SWITCHING CHARACTERISTICS—MAX13486E (continued) Typical Operating Characteristics (continued) (VCC = +5V, TA = +25°C, unless otherwise noted.) RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE 4.8 4.6 4.4 0.4 0.3 0.2 80 MAX13485-86E toc06 IO = 1mA OUTPUT CURRENT (mA) 5.0 MAX13485-86E toc05 OUTPUT HIGH VOLTAGE (V) 5.2 DIFFERENTIAL OUPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE 0.5 OUTPUT LOW VOLTAGE (V) IO = 1mA RECEIVER OUTPUT LOW VOLTAGE vs. TEMPERATURE MAX13485-86E toc04 5.4 60 40 20 0.1 4.2 4.0 -15 10 35 60 85 -40 -15 10 35 60 0 85 2 3 DRIVER-DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE OUTPUT CURRENT vs. TRANSMITTER OUTPUT HIGH VOLTAGE OUTPUT CURRENT vs. TRANSMITTER OUTPUT LOW VOLTAGE 1.5 1.0 0.5 80 60 40 100 35 60 -7 -6 -5 -4 -3 -2 -1 0 85 60 40 0 0 10 80 20 20 -15 MAX13485-86E toc09 MAX13485-86E toc08 100 120 OUTPUT CURRENT (mA) 2.0 120 OUTPUT CURRENT (mA) 2.5 MAX13485-86E toc07 OUTPUT VOLTAGE (V) 0 1 2 3 4 5 0 2 4 6 8 10 TEMPERATURE (°C) OUTPUT HIGH VOLTAGE (V) OUTPUT LOW VOLTAGE (V) SHUTDOWN CURRENT vs. TEMPERATURE DRIVER PROPAGATION vs. TEMPERATURE (MAX13485E) DRIVER PROPAGATION DELAY vs. TEMPERATURE (MAX13486E) 6 5 4 3 2 500 tDPHL 450 400 350 12 MAX13485-86E toc12 7 tDPLH 550 30 DRIVER PROPAGATION DELAY (ns) 8 600 MAX13485-86E toc11 9 DRIVER PROPAGATION DELAY (ns) MAX13485-86E toc10 10 25 20 15 10 tDPLH 5 1 tDPHL 300 0 -40 -15 10 35 TEMPERATURE (°C) 6 5 4 TEMPERATURE (°C) RDIFF = 54Ω -40 1 TEMPERATURE (°C) 3.0 DIFFERENTIAL OUTPUT VOLTAGE (V) 0 0 -40 SHUTDOWN CURRENT (µA) MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN 60 85 0 -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 TEMPERATURE (°C) _______________________________________________________________________________________ 60 85 Half-Duplex RS-485/RS-422 Transceivers in µDFN RECEIVER PROPAGATION vs. TEMPERATURE (MAX13485E) tRPHL 40 20 MAX13485-86E toc14 60 DRIVER PROPAGATION (500kbps) (MAX13485E) MAX13485/86E toc15 40 RECEIVER PROPAGATION (ns) MAX13485-86E toc13 PROPAGATION DELAY (ns) 80 RECEIVER PROPAGATION vs. TEMPERATURE (MAX13486E) 30 DI 2V/div tRPLH 20 tRPHL A-B 5V/div 10 tRPLH 0 0 -40 -15 10 35 60 85 -40 TEMPERATURE (°C) -15 10 35 60 85 400ns/div TEMPERATURE (°C) DRIVER PROPAGATION (16Mbps) (MAX13486E) RECEIVER PROPAGATION (16Mbps) (MAX13486E) MAX13485/86E toc16 MAX13485/86E toc17 B 2V/div DI 2V/div A 2V/div A-B 5V/div 10ns/div RO 2V/div 10ns/div _______________________________________________________________________________________ 7 MAX13485E/MAX13486E Typical Operating Characteristics (continued) (VCC = +5V, TA = +25°C, unless otherwise noted.) MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN Test Circuits and Waveforms A 5V RDIFF DE 2 A DI VOD VID CL RDIFF B RDIFF VOC 2 B Figure 2. Driver Timing Test Circuit Figure 1. Driver DC Test Load f = 1MHz, tLH ≤ 3ns, tHL ≤ 3ns VCC DI 1.5V 1.5V 0 1/2 VO tDPHL tDPLH B A 1/2 VO VO VDIFF = V(A) - V(B) VO VDIFF 90% 90% 0 10% 10% -VO tHL tLH tDSKEW = |tDPLH - tDPHL| Figure 3. Driver Propagation Delays 8 _______________________________________________________________________________________ CL Half-Duplex RS-485/RS-422 Transceivers in µDFN VCC DE 1.5V 1.5V 0 tDLZ tDZL(SHDN),tDZL A, B 2.3V VOL + 0.5V OUTPUT NORMALLY LOW VOL OUTPUT NORMALLY HIGH A, B 2.3V VOH + 0.5V 0 tDZH(SHDN),tDZH tDHZ Figure 4. Driver Enable and Disable Times 500Ω S1 VCC B OUTPUT UNDER TEST R VID ATE CL RECEIVER OUTPUT A S2 Figure 5. Driver-Enable and -Disable-Timing Test Load Figure 6. Receiver Propagation Delay Test Circuit f = 1MHz, tLH ≤ 3ns, tHL ≤ 3ns A 1V B -1V tRPHL tRPLH VOH RO 1.5V VOL 1.5V tRSKEW = |tRPHL - tRPLH| Figure 7. Receiver Propagation Delays _______________________________________________________________________________________ 9 MAX13485E/MAX13486E Test Circuits and Waveforms (continued) MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN Pin Description PIN NAME FUNCTION 1 RO Receiver Output 2 RE Receiver Output Enable. Drive RE low to enable RO. RO is high impedance when RE is high. Drive RE high and DE low to enter low-power shutdown mode. RE is a hot-swap input (see the Hot-Swap Capability section for more details). 3 DE Driver Output Enable. Drive DE high to enable the driver outputs. These outputs are high-impedance when DE is low. Drive RE high and DE low to enter low-power shutdown mode. DE is a hot-swap input (see the Hot-Swap Capability section for more details). 4 DI Driver Input. Drive DI low to force noninverting output low and inverting output high. Drive DI high to force noninverting output high and inverting output low (see the Function Tables). 5 GND 6 A Noninverting Receiver Input and Noninverting Driver Output 7 B Inverting Receiver Input and Inverting Driver Output 8 VCC Ground Positive Supply, VCC = +5V ±5%. Bypass VCC to GND with a 0.1µF capacitor. Function Tables TRANSMITTING INPUT OUTPUT RE DE DI B A X 1 1 0 1 X 1 0 1 0 0 0 X HIGH IMPEDANCE HIGH IMPEDANCE 1 0 X SHUTDOWN RECEIVING INPUT OUTPUT RE DE 0 X > -50mV 1 0 X < -200mV 0 0 X OPEN/SHORT 1 A-B RO 1 1 X HIGH IMPEDANCE 1 0 X SHUTDOWN X = Don’t care, shutdown mode, driver, and receiver outputs are in high impedance. 10 ______________________________________________________________________ Half-Duplex RS-485/RS-422 Transceivers in µDFN S1 +1V S3 VCC 1kΩ -1V VID CL 15pF GENERATOR S2 50Ω S1 OPEN S2 CLOSED S3 = +1V S1 CLOSED S2 OPEN S3 = -1V VCC VCC VCC/2 VCC/2 RE RE 0 0 tRZH, tRZH(SHDN) tRZL, tRZL(SHDN) VOH RO VCC VOH/2 (VOL + VCC)/2 RO 0 S1 OPEN S2 CLOSED S3 = +1V VOL S1 CLOSED S2 OPEN S3 = -1V VCC VCC/2 VCC/2 RE 0 RE VCC 0 tRLZ tRHZ VCC VOH RO 0.25V 0 RO 0.25V Figure 8. Receiver Enable and Disable Times __________________________________________________________________________ VOL MAX13485E/MAX13486E Test Circuits and Waveforms (continued) MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN Detailed Description The MAX13485E/MAX13486E half-duplex, high-speed transceivers for RS-485/RS-422 communication contain one driver and one receiver. These devices feature failsafe circuitry that guarantees a logic-high receiver output when receiver inputs are open or shorted, or when they are connected to a terminated transmission line with all drivers disabled (see the Fail-Safe section). The MAX13485E/MAX13486E also feature a hot-swap capability allowing line insertion without erroneous data transfer (see the Hot-Swap Capability section). The MAX13485E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free transmission up to 500kbps. The MAX13486E driver slew rate is not limited, making transmit speeds up to 16Mbps possible. VCC 10µs TIMER SR LATCH TIMER 5kΩ DE (HOT SWAP) DE Fail-Safe The MAX13485E/MAX13486E guarantee a logic-high receiver output when the receiver inputs are shorted or open, or when they are connected to a terminated transmission line with all drivers disabled. This is done by setting the receiver input threshold between -50mV and -200mV. If the differential receiver input voltage (A - B) is greater than or equal to -50mV, RO is logic-high. If (A - B) is less than or equal to -200mV, RO is logic-low. In the case of a terminated bus with all transmitters disabled, the receiver’s differential input voltage is pulled to 0V by the termination. With the receiver thresholds of the MAX13485E/MAX13486E, this results is a logic-high with a 50mV minimum noise margin. Unlike previous fail-safe devices, the -50mV to -200mV threshold complies with the ±200mV EIA/TIA-485 standard. Hot-Swap Capability Hot-Swap Inputs When circuit boards are inserted into a hot or powered backplane, differential disturbances to the data bus can lead to data errors. Upon initial circuit-board insertion, the data communication processor undergoes its own power-up sequence. During this period, the processor’s logic-output drivers are high impedance and are unable to drive the DE and RE inputs of these devices to a defined logic level. Leakage currents up to ±10µA from the high impedance state of the processor’s logic drivers could cause standard CMOS enable inputs of a transceiver to drift to an incorrect logic level. Additionally, parasitic circuit-board capacitance could cause coupling of VCC or GND to the enable inputs. Without the hot-swap capability, these factors could improperly enable the transceiver’s driver or receiver. 12 100µA 500µA M1 M2 Figure 9. Simplified Structure of the Driver Enable Pin (DE) When VCC rises, an internal pulldown circuit holds DE low and RE high. After the initial power-up sequence, the pulldown circuit becomes transparent, resetting the hot-swap tolerable input. Hot-Swap Input Circuitry The enable inputs feature hot-swap capability. At the input there are two nMOS devices, M1 and M2 (Figure 9). When VCC ramps from zero, an internal 7µs timer turns on M2 and sets the SR latch, which also turns on M1. Transistors M2, a 1.5mA current sink, and M1, a 500µA current sink, pull DE to GND through a 5kΩ resistor. M2 is designed to pull DE to the disabled state against an external parasitic capacitance up to 100pF that can drive DE high. After 7µs, the timer deactivates M2 while M1 remains on, holding DE low against tristate leakages that can drive DE high. M1 remains on until an external source overcomes the required input current. At this time, the SR latch resets and M1 turns off. When M1 turns off, DE reverts to a standard highimpedance CMOS input. Whenever VCC drops below 1V, the hot-swap input is reset. For RE there is a complementary circuit employing two pMOS devices pulling RE to VCC. ______________________________________________________________________________________ Half-Duplex RS-485/RS-422 Transceivers in µDFN CHARGE-CURRENT LIMIT RESISTOR HIGHVOLTAGE DC SOURCE Cs 100pF RC 50MΩ TO 100MΩ RD 1500Ω CHARGE-CURRENT LIMIT RESISTOR DISCHARGE RESISTANCE DEVICE UNDER TEST STORAGE CAPACITOR Figure 10a. Human Body ESD Test Model IP 100% 90% Cs 150pF RD 330Ω DISCHARGE RESISTANCE STORAGE CAPACITOR DEVICE UNDER TEST Figure 10c. ICE 61000-4-2 ESD Test Model I 100% 90% PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) IPEAK Ir HIGHVOLTAGE DC SOURCE MAX13485E/MAX13486E RC 1MΩ AMPS 36.8% 10% 0 10% 0 tRL TIME tr = 0.7ns TO 1ns tDL CURRENT WAVEFORM Figure 10b. Human Body Current Waveform +15V 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 MAX13485E/MAX13486E 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, the MAX13485E/MAX13486E keep working without latchup or damage. ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the MAX13485E/ MAX13486E are characterized for protection to the following limits: • ±15kV using the Human Body Model • ±15kV using the Air Gap Discharge Method specified in IEC 61000-4-2 (MAX13485E only) t 30ns 60ns Figure 10d. IEC 61000-4-2 ESD Generator Current Waveform 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 10a shows the Human Body Model, and Figure 10b shows the current waveform it generates when discharged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kΩ resistor. IEC 61000-4-2 The IEC 61000-4-2 standard covers ESD testing and performance of finished equipment. However, it does not specifically refer to integrated circuits. The MAX13485E/MAX13486E help equipment designs to meet IEC 61000-4-2, without the need for additional ESD-protection components. The major difference between tests done using the Human Body Model and IEC 61000-4-2 is higher peak current in IEC 61000-4-2 because series resistance is lower in the IEC 61000-4-2 model. Hence, the ESD ______________________________________________________________________________________ 13 MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN DI D Rt D Rt DE RO RE DI DE R R R MAX13485E MAX13486E R D D DI RO RE DE RO RE DI DE RO RE Figure 11. Typical Half-Duplex RS-485 Network withstand voltage measured to IEC 61000-4-2 is generally lower than that measured using the Human Body Model. Figure 10c shows the IEC 61000-4-2 model, and Figure 10d shows the current waveform for the IEC 61000-4-2 ESD Contact Discharge test. Machine Model The machine model for ESD tests all pins using a 200pF storage capacitor and zero discharge resistance. The objective is to emulate the stress caused when I/O pins are contacted by handling equipment during test and assembly. Of course, all pins require this protection, not just RS-485 inputs and outputs. 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. Enable times tZH and tZL (see the Switching Characteristics) assume the devices were not in a low-power shutdown state. Enable times t ZH(SHDN) and t ZL(SHDN) assume the devices were in shutdown state. It takes drivers and receivers longer to become enabled from lowpower shutdown mode (tZH(SHDN), tZL(SHDN)) than from driver-/receiver-disable mode (tZH, tZL). Applications Information Line Length 128 Transceivers on the Bus The RS-485/RS-422 standard covers line lengths up to 4000ft. The standard RS-485 receiver input impedance is 12kΩ (1-unit load), and the standard driver can drive up to 32-unit loads. The MAX13485E/MAX13486E have a 1/4unit load receiver input impedance (48kΩ), allowing up to 128 transceivers to be connected in parallel on one communication line. Any combination of these devices, as well as other RS-485 transceivers with a total of 32unit loads or fewer, can be connected to the line. Reduced EMI and Reflections The MAX13485E features reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly terminated cables, allowing error-free data transmission up to 500kbps. 14 Low-Power Shutdown Mode Low-power shutdown mode is initiated by bringing both RE high and DE low. In shutdown, the devices draw a maximum of 10µA of supply current. RE and DE can be driven simultaneously. The devices are guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 700ns, the devices are guaranteed to enter shutdown. Typical Applications The MAX13485E/MAX13486E transceivers are designed for half-duplex, bidirectional data communications on multipoint bus transmission lines. Figure 11 shows typical network applications circuits. To minimize reflections, terminate the line at both ends in its characteristic impedance, and keep stub lengths off the main line as short as possible. The slew-rate-limited MAX13485E is more tolerant of imperfect termination. Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ Half-Duplex RS-485/RS-422 Transceivers in µDFN N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D A B e C 0 -8 A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 1 ______________________________________________________________________________________ 15 MAX13485E/MAX13486E Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) A D XXXX XXXX XXXX b e 6, 8, 10L UDFN.EPS MAX13485E/MAX13486E Half-Duplex RS-485/RS-422 Transceivers in µDFN N SOLDER MASK COVERAGE E PIN 1 0.10x45 L L1 1 SAMPLE MARKING PIN 1 INDEX AREA A A (N/2 -1) x e) 7 CL CL b L L A A2 e EVEN TERMINAL A1 e ODD TERMINAL PACKAGE OUTLINE, 6, 8, 10L uDFN, 2x2x0.80 mm 21-0164 -DRAWING NOT TO SCALE- A 1 2 COMMON DIMENSIONS SYMBOL MIN. NOM. MAX. A 0.70 0.75 0.80 A1 0.15 0.20 0.25 A2 0.020 0.025 0.035 D 1.95 2.00 E 1.95 2.00 L 0.30 0.40 L1 - 2.05 2.05 0.50 0.10 REF. PACKAGE VARIATIONS PKG. CODE N e b (N/2 -1) x e L622-1 6 0.65 BSC 0.30–0.05 1.30 REF. L822-1 8 0.50 BSC 0.25–0.05 1.50 REF. L1022-1 10 0.40 BSC 0.20–0.03 1.60 REF. PACKAGE OUTLINE, 6, 8, 10L uDFN, 2x2x0.80 mm -DRAWING NOT TO SCALE- 21-0164 A 2 2 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2007 Maxim Integrated Products Boblet is a registered trademark of Maxim Integrated Products, Inc.