EVALUATION KIT AVAILABLE MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection General Description The MAX14782E is a 3.3V to 5V ESD-protected transceiver intended for half-duplex RS-485/RS-422 communication up to 500kbps. The device is optimized for extended cable runs while maximizing tolerance to noise. The MAX14782E integrated protection features include short-circuit-protected outputs, hot-swap functionality, and a true fail-safe receiver, guaranteeing a logic-high receiver output when inputs are shorted or open. Hotswap capability eliminates undesired transitions on the bus during power-up or hot insertion. The transceiver draws 1.9mA (typ) supply current when unloaded or when fully loaded with the drivers disabled and draws less than 10µA (max) of supply current in lowpower shutdown mode. The MAX14782E is available in 8-pin µMAX®, 8-pin SO, and small, 8-pin (3mm x 3mm) TDFN-EP packages. All packages operate over the -40°C to +125°C temperature range. Benefits and Features ● Integrated Protection Increases Robustness • High ESD Protection ±35kV HBM ESD ±20kV Air Gap IEC 61000-4-2 ESD ±12kV Contact IEC 61000-4-2 ESD • Short-Circuit-Protected Outputs • True Fail-Safe Receiver • Hot-Swap Capability ● 3V to 5.5V Supply Voltage Range ● Data Rates up to 500kbps ● -40°C to +125°C Operating Temperature ● Allows Up to 32 Transceivers On the Bus ● Low 10µA (max) Shutdown Current ● Saves Board Space Applications ● ● ● ● • Available in 8-pin µMAX, SO, and TDFN-EP Packages Motion Controllers Field Bus Networks Encoder Interfaces Backplane Buses Ordering Information/Selector Guide PART SUPPLY RANGE DATA RATE (MAX) TEMP RANGE MAX14782EASA+ 3.0V to 5.5V 500kbps -40°C to +125°C 8 SO MAX14782EATA+ 3.0V to 5.5V 500kbps -40°C to +125°C 8 TDFN-EP* MAX14782EAUA+ 3.0V to 5.5V 500kbps -40°C to +125°C 8 µMAX µMax is a registered trademark of Maxim Integrated Products, Inc. +Denotes lead(Pb)-free/RoHS-compliant package. *EP = Exposed paddle. 19-6776; Rev 0; 8/13 PIN-PACKAGE MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Absolute Maximum Ratings (Voltages referenced to GND.) VCC ......................................................................-0.3V to +6.0V RO............................................................. -0.3V to (VCC + 0.3V) RE, DE, DI.............................................................-0.3V to +6.0V A, B (VCC ≥ 3.6V) ..............................................-8.0V to +13.0V A, B (VCC < 3.6V) .............................................-9.0V to +13.0V Short-Circuit Duration (RO, A, B) to GND..................Continuous Operating Temperature Range MAX14782EA_.............................................. -40°C to +125°C Junction Temperature.......................................................+150°C Storage Temperature Range............................. -65°C to +150°C Continuous Power Dissipation (TA = +70°C) SO (derate at 7.6mW/°C above +70°C).......................606mW TDFN-EP (derate at 24.4mW/°C above +70°C).........1951mW µMAX (derate at 4.8mW/°C above +70°C)..................387mW Lead Temperature (soldering, 10s).................................. +300ºC Soldering Temperature (reflow)....................................... +260°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. Package Thermal Characteristics (Note 1) Junction-to-Case Thermal Resistance (θJC) SO................................................................................38°C/W TDFN-EP........................................................................8°C/W µMAX............................................................................42°C/W Junction-to-Ambient Thermal Resistance (θJA) SO..............................................................................132°C/W TDFN-EP......................................................................41°C/W µMAX..........................................................................206°C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. Electrical Characteristics (VCC = +3.0V to +5.5V, TA = TMIN to TMAX, unless otherwise specified. Typical values are at VCC = +5V and TA = +25°C.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V 4 mA 10 µA POWER SUPPLY Supply Voltage Supply Current Shutdown Supply Current 3.0 VCC ICC ISHDN DE = VCC, RE = GND, no load 1.9 DE = GND, RE = VCC DRIVER Differential Driver Output Change in Magnitude of Differential Output Voltage Driver Common-Mode Output Voltage Change in Magnitude of CommonMode Voltage VOD ΔVOD VOC ΔVOC VCC = 4.5V, RL = 54Ω, Figure 1 2.1 VCC = 3V, RL = 100Ω, Figure 1 2.0 VCC = 3V, RL = 54Ω, Figure 1 1.5 RL = 54Ω or 100Ω, Figure 1 (Note 4) -0.2 RL = 54Ω or 100Ω, Figure 1 RL = 54Ω or 100Ω, Figure 1 (Note 4) -0.2 2.2 Single-Ended Driver Output High VOH A or B output, IA or B = -20mA Single-Ended Driver Output Low VOL A or B output, IA or B = 20mA Differential Output Capacitance COD DE = RE = VCC, f = 4MHz Driver Short-Circuit Output Current www.maximintegrated.com |IOST| V 0 +0.2 V VCC / 2 3 V +0.2 V V 0.8 12 V pF 0 ≤ VOUT ≤ +12V, output low 250 -7V ≤ VOUT ≤ VCC, output high 250 mA Maxim Integrated │ 2 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Electrical Characteristics (continued) (VCC = +3.0V to +5.5V, TA = TMIN to TMAX, unless otherwise specified. Typical values are at VCC = +5V and TA = +25°C.) (Notes 2, 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 400 1000 UNITS RECEIVER VIN = +12V Input Current IA, B DE = GND, VCC = GND or +5.5V Differential Input Capacitance CA, B Between A and B, DE = GND, f = 4MHz Receiver Differential Threshold Voltage VTH VIN = -7V -7V ≤ VCM ≤ +12V -800 +300 12 -200 pF -10 ΔVTH Receiver Input Resistance RIN -7V ≤ VCM ≤ +12V 12 kΩ Input-Voltage High VIH DE, DI, RE 2.0 V Input-Voltage Low Input Hysteresis Input Current VIL DE, DI, RE VHYS DE, DI, RE IIN DE, DI, RE Input Impedance on First Transition DE, RE 10 mV Receiver Input Hysteresis LOGIC INTERFACE (DI, DE, RE, RO) VCM = 0V -105 µA mV 0.8 50 1 V mV ±1 µA 10 kΩ RO Output-Voltage High VOHRO RE = GND, IRO = -2mA, (VA - VB) > 200mV RO Output-Voltage Low VOLRO RE = GND, IRO = 2mA, (VA - VB) < -200mV 0.4 V ±1 µA ±110 mA Receiver Three-State Output Current IOZR RE = VCC, 0 ≤ VRO ≤ VCC Receiver Output Short-Circuit Current IOSR 0 ≤ VRO ≤ VCC VCC - 1.5 V PROTECTION Thermal-Shutdown Threshold TSHDN Temperature rising Thermal-Shutdown Hysteresis ESD Protection on A and B Pins ESD Protection, All Other Pins www.maximintegrated.com +160 °C 15 °C IEC 61000-4-2 Air-Gap Discharge to GND ±20 IEC 61000-4-2 Contact Discharge to GND ±12 Human Body Model ±35 Human Body Model ±2 kV kV Maxim Integrated │ 3 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Switching Characteristics (VCC = +3V to +5.5V, TA = TMIN to TMAX, unless otherwise specified. Typical values are at VCC = +5V and TA = +25°C.) (Notes 2, 3, 5) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DRIVER Driver Propagation Delay tDPLH tDPHL 20 RL = 54Ω, CL = 50pF, Figures 2 and 3 Driver Differential Output Rise or Fall Time tHL, tLH RL = 54Ω, CL = 50pF, Figures 2 and 3 Differential Driver Output Skew |tDPLH - tDPHL| tDSKEW RL = 54Ω, CL = 50pF, Figures 2 and 3 Maximum Data Rate DRMAX 20 200 ns 600 ns 140 ns kbps 500 Driver Enable to Output High tDZH RL = 110Ω, CL = 50pF, Figures 4 and 5 (Note 6) 2500 ns Driver Enable to Output Low tDZL RL = 110Ω, CL = 50pF, Figures 4 and 5 (Note 6) 2500 ns Driver Disable Time from Low tDLZ RL = 110Ω, CL = 50pF, Figures 4 and 5 100 ns Driver Disable Time from High tDHZ RL = 110Ω, CL = 50pF, Figures 4 and 5 100 ns RL = 110Ω, CL = 15pF, Figures 4 and 5 (Note 6) 5.5 µs Driver Enable from Shutdown to Output High www.maximintegrated.com tDLZ(SHDN) Maxim Integrated │ 4 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Switching Characteristics MAX14782E (continued) (VCC = +3V to +5.5V, TA = TMIN to TMAX, unless otherwise specified. Typical values are at VCC = +5V and TA = +25°C.) (Notes 2, 3, 5) PARAMETER Driver Enable from Shutdown to Output Low Time to Shutdown SYMBOL tDHZ(SHDN) tSHDN CONDITIONS MIN TYP RL = 110Ω, CL = 15pF, Figures 4 and 5 (Note 6) (Note 7) 50 340 MAX UNITS 5.5 µs 700 ns RECEIVER Receiver Propagation Delay tRPLH tRPHL Receiver Output Skew tRSKEW Maximum Data Rate DRMAX 200 CL = 15pF, Figures 6 and 7 200 CL = 15pF, Figures 6 and 7 (Note 6) 30 500 ns ns kbps Receiver Enable to Output High tRZH RL = 1kΩ, CL = 15pF, Figure 8 (Note 6) 50 ns Receiver Enable to Output Low tRZL RL = 1kΩ, CL = 15pF, Figure 8 (Note 6) 50 ns Receiver Disable Time from Low tRLZ RL = 1kΩ, CL = 15pF, Figure 8 50 ns Receiver Disable Time from High tRHZ RL = 1kΩ, CL = 15pF, Figure 8 50 ns Receiver Enable from Shutdown to Output High tRLZ(SHDN) RL = 1kΩ, CL = 15pF, Figure 8 (Note 6) 5.5 µs Receiver Enable from Shutdown to Output Low tRHZ(SHDN) RL = 1kΩ, CL = 15pF, Figure 8 (Note 6) 5.5 µs 700 ns Time to Shutdown tSHDN (Note 7) 50 340 Note 2: All devices 100% production tested at TA = +25°C. Specifications over temperature are guaranteed by design. Note 3: All currents into the device are positive; all currents out of the device are negative. All voltages are referenced to ground, unless otherwise noted. Note 4: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 5: Capacitive load includes test probe and fixture capacitance. Note 6: Guaranteed by design; not production tested. Note 7: The timing parameter refers to the driver or receiver enable delay, when the device has exited the initial hot-swap protect state and is in normal operating mode. www.maximintegrated.com Maxim Integrated │ 5 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Test and Timing Diagrams A VCC DE RL 2 DI A VOD B VOD RL 2 RL CL VOC B Figure 1. Driver DC Test Load Figure 2. Driver Timing Test Circuit f = 1MHz, tLH = 3ns, tHL = 3ns VCC DI 1.5V 1.5V 0 tDPHL tDPLH B A VOD VOD = [VA - VB] VO VOD 90% 0 -VO 90% 10% 10% tLH tHL tDSKEW = |tDPLH - tDPHL| Figure 3. Driver Propagation Delays www.maximintegrated.com Maxim Integrated │ 6 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection GND OR VCC DI D A B S1 VCC OUT CL 50pF RL = 110Ω DE 1.5V tDZH, tDZH(SHDN) DE GENERATOR 0 0.25V OUT 50Ω VOH 1.5V 0 tDHZ Figure 4. Driver Enable and Disable Times (tDHZ, tDZH) VCC 0 OR VCC DI D A RL = 110Ω S1 VCC OUT B VCC OUT DE GENERATOR DE 50Ω 1.5V tDZL, tDZL(SHDN) 0 tDLZ 1.5V VOL 0.25V Figure 5. Driver Enable and Disable Times (tDZL, tDZL) A ATE R VID RO B Figure 6. Receiver Propagation Delay Test Circuit www.maximintegrated.com Maxim Integrated │ 7 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection A 1V B -1V tRPHL VOH RO tRPLH 1.5V 1.5V VOL tRSKEW = |tRPHL - tRPLH| Figure 7. Receiver Propagation Delays +1.5V S3 -1.5V VID R RO RE GENERATOR 1.5V tRZH, tRZH(SHDN) RO 0 S1 OPEN S2 CLOSED S3 = +1.5V VCC 1.5V tRHZ RO 0.25V VCC S2 CL 15pF VCC 1.5V RE 0 S1 CLOSED S2 OPEN S3 = -1.5V tRZL, tRZL(SHDN) VOH VCC 2 0 RE S1 50Ω VCC RE R 1kΩ 0 VCC 2 VOL RO VCC S1 OPEN S2 CLOSED S3 = +1.5V 1.5V RE tRLZ 0 S1 CLOSED S2 OPEN S3 = -1.5V VCC VOH 0 VCC RO 0.25V VOL Figure 8. Receiver Enable and Disable Times www.maximintegrated.com Maxim Integrated │ 8 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Typical Operating Characteristics (VCC = +5V, TA = +25°C, unless otherwise specified.) 1.5 VCC = 3.3V 1.0 VCC = 5V VCC = 3.3V 3 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 MAX14782E toc03 60 VCC = 3.3V, 54Ω LOAD 50 40 VCC = 5V, NO LOAD 30 VCC = 3.3V, NO LOAD 20 10 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 100 0 200 300 400 500 RECEIVER-OUTPUT HIGH VOLTAGE vs. OUTPUT CURRENT RECEIVER-OUTPUT LOW VOLTAGE vs. OUTPUT CURRENT DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE VCC = 3.3V 1 -10 -20 -30 -40 -60 -50 4 3 2 VCC = 3.3V 1 0 5.0 4.5 10 20 30 40 50 RL = 54Ω CL = 50pF VCC = 5V 3.5 3.0 2.5 2.0 1.5 VCC = 3.3V 1.0 60 120 VCC = 5V 80 40 0 VCC = 3.3V 0 1 2 3 4 5 DIFFERENTIAL OUTPUT VOLTAGE (V) DIFFERENTIAL DRIVER OUTPUT VOLTAGE vs. TEMPERATURE 4.0 -180 -160 DRIVER OUTPUT CURRENT vs. OUTPUT HIGH VOLTAGE VCC = 5V -140 -120 -100 VCC = 3.3V -80 -60 -40 -20 0.5 0 0 OUTPUT CURRENT (mA) MAX14782E toc07 DIFFERENTIAL DRIVER OUTPUT VOLTAGE (V) OUTPUT CURRENT (mA) VCC = 5V 160 MAX14782E toc08 2 OUTPUT SINKING CURRENT DRIVER OUTPUT CURRENT (mA) VCC = 5V 3 OUTPUT LOW VOLTAGE (V) 4 5 MAX14782E toc06 DATA RATE (kbps) MAX14782E toc05 TEMPERATURE (°C) OUTPUT SOURCING CURRENT 0 VCC = 5V, 54Ω LOAD TEMPERATURE (°C) MAX14782E toc04 OUTPUT HIGH VOLTAGE (V) 5 1 5 0 6 2 0.5 0 7 4 DE = VCC 70 SUPPLY CURRENT (mA) 2.0 8 OUTPUT CURRENT (mA) SUPPLY CURENT (mA) VCC = 5V DE = GND RE = VCC 9 SUPPLY CURRENT vs. DATA RATE 80 MAX14782E toc02 DE = VCC RE = GND 2.5 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE 10 SUPPLY CURENT (µA) 3.0 MAX14782E toc01 NO-LOAD SUPPLY CURRENT vs. TEMPERATURE -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) www.maximintegrated.com 0 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 OUTPUT HIGH VOLTAGE (V) Maxim Integrated │ 9 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Typical Operating Characteristics (continued) (VCC = +5V, TA = +25°C, unless otherwise specified.) VCC = 3.3V 80 60 40 450 400 350 250 0 200 6 8 10 12 14 VCC = 5V 12 10 8 6 4 2 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) DRIVER-OUTPUT RISE /FALL TIME vs. TEMPERATURE DRIVER-OUTPUT TRANSITION SKEW vs. TEMPERATURE RECEIVER PROPAGATION DELAY vs. TEMPERATURE tHL, VCC = 5V tHL, VCC = 3.3V tLH, VCC = 3.3V -40 -25 -10 5 20 35 50 65 80 95 110 125 RL = 54Ω CL = 50pF 2.5 200 180 2.0 1.5 VCC = 3.3V 1.0 0.5 0 120 100 80 tRPLH, VCC = 5V 40 CL = 15pF -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) DRIVER/RECEIVER PROPAGATION DELAY DIFFERENTIAL INPUT CAPACITANCE vs. FREQUENCY 30 MAX14782E toc15 DE = GND VCC = 3.3V CL = 8pF A /B 2V/div RO 20 10 2V/div 400ns/div www.maximintegrated.com CAPACITANCE (pF) 2V/div DI tRPLH, VCC = 3.3V 60 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) tRPHL, VCC = 3.3V 140 20 VCC = 5V tRPHL, VCC = 5V 160 MAX14782E toc16 tLH, VCC = 5V 3.0 MAX14782E toc13 RL = 54Ω CL = 50pF MAX14782E toc11 VCC = 3.3V TEMPERATURE (°C) 100 0 16 RL = 54Ω CL = 50pF OUTPUT LOW VOLTAGE (V) 300 200 tDPHL, VCC = 3.3V PROPAGATION DELAY (ns) 400 4 DRIVER-OUTPUT TRANSITION SKEW (ns) 500 2 tDPLH, VCC = 3.3V 300 20 0 tDPHL, VCC = 5V tDPLH, VCC = 5V 18 DIFFERENTIAL DRIVER SKEW vs. TEMPERATURE MAX14782E toc14 100 500 DRIVER DIFFERENTIAL SKEW (ns) 120 RL = 54Ω CL = 50pF 550 20 MAX14782E toc10 140 DRIVER PROPAGATION DELAY vs. TEMPERATURE 600 PROPAGATION DELAY (ns) 160 600 DRIVER-OUTPUT RISE/FALL TIME (ns) VCC = 5V MAX14782E toc12 DRIVER OUTPUT CURENT (mA) 180 MAX14782E toc09 DRIVER OUTPUT CURRENT vs. OUTPUT LOW VOLTAGE 0 0 3 30 FREQUENCY (MHz) Maxim Integrated │ 10 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Pin Configuration TOP VIEW VCC B A GND 8 7 6 5 MAX14782E + 8 VCC 7 B 3 6 A 4 5 GND RO 1 RE 2 DE DI MAX14782E *EP + 1 2 3 4 RO RE DE DI µMAX/SO TDFN-EP *CONNECT EXPOSED PAD (EP) TO GND Pin Description PIN NAME 1 RO Receiver Output. See Function Tables. 2 RE Receiver Output Enable. Drive RE low to enable RO. Drive RE high to disable the receiver. RO is high impedance when RE is high. Drive RE high and pull DE low to enter low-power shutdown mode. 3 DE Driver Output Enable. Drive DE high to enable the driver. Drive DE low to disable the driver. Driver outputs are high-impedance when the driver is disabled. Drive RE high and pull DE low to enter lowpower shutdown mode. 4 DI Driver Input. With DE high, a low on DI forces the A output low and the B output high. Similarly, a high on DI forces the A output high and B output low. 5 GND 6 A Noninverting RS-485/RS-422 Receiver Input and Driver Output 7 B Inverting RS-485/RS-422 Receiver Input and Driver Output 8 VCC — EP www.maximintegrated.com FUNCTION Ground Positive Supply Voltage Input. Bypass VCC with a 0.1µF ceramic capacitor to ground. Exposed Pad (TDFN only). Connect EP to GND. Maxim Integrated │ 11 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Function Tables TRANSMITTING RE INPUTS OUTPUTS MODE DE DI B A X 1 1 0 1 Active X 1 0 1 0 Active 0 0 X High Impedance Driver Disabled 1 0 X High Impedance Shutdown RECEIVING RE INPUTS DE OUTPUTS A-B RO MODE 0 X ≥ -10mV 1 Active 0 X ≤ -200mV 0 Active 0 X Open/Shorted 1 Active 1 1 X High Impedance Receiver Disabled 0 X High Impedance Shutdown 1 X = Don’t care Functional Diagram VCC MAX14782E RO R RE B SHUTDOWN A DE DI D GND www.maximintegrated.com Maxim Integrated │ 12 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Detailed Description Hot-Swap Capability The MAX14782E is a 3.3V to 5V ESD-protected RS-485/ RS-422 transceiver intended for high-speed, half-duplex communications. Integrated hot-swap functionality eliminates false transitions on the bus during power-up or hot insertion. The device features fail-safe receiver inputs guaranteeing a logic-high receiver output when inputs are shorted or open. The IC has a 1-unit load receiver input impedance, allowing up to 32 transceivers on the bus. True Fail Safe The MAX14782E guarantees 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. If the differential receiver input voltage (A–B) is greater than or equal to -10mV, RO is logic-high. Driver Single-Ended Operation The A and B outputs can either be used in the standard differential operating mode, or can be used as singleended outputs. Since the A and B driver outputs swing rail-to-rail, they can individually be used as standard TTL logic outputs. Hot-Swap Inputs When circuit boards are inserted in a hot or powered backplane, disturbances on the enable inputs and differential receiver inputs can lead to data errors. Upon initial circuit board insertion, the processor undergoes its power-up sequence. During this period, the processor output drivers are high impedance and are unable to drive the DE and RE inputs of the MAX14782E to a defined logic level. Leakage currents up to 10µA from the highimpedance outputs of a controller could cause DE and RE to drift to an incorrect logic state. Additionally, parasitic circuit board capacitance could cause coupling of VCC or GND to DE and RE. These factors could improperly enable the driver or receiver. The MAX14782E features integrated hot-swap inputs that help to avoid these potential problems. 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 hotswap-tolerable inputs. Hot-Swap Input Circuitry The DE and RE enable inputs feature hot-swap capability. At the input, there are two nMOS devices, M1 and M2 (Figure 9). When VCC ramps from 0V, an internal 10µs timer turns on M2 and sets the SR latch that also turns VCC 10µs TIMER TIMER DE DRIVER ENABLE (HOT SWAP) 5kΩ (typ) 100µA M1 500µA M2 Figure 9. Simplified Structure of the Driver Enable (DE) Pin www.maximintegrated.com Maxim Integrated │ 13 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection on M1. Transistors M2 (a 500µA current sink) and M1 (a 100µA current sink) pull DE to GND through a 5kΩ (typ) 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 10µs, the timer deactivates M2 while M1 remains on, holding DE low against three-state 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, high-impedance CMOS input. Whenever VCC drops below 1V, the hotswap input is reset. ● ±35kV HBM A complementary circuit employing two pMOS devices pulls RE to VCC. Figure 10 shows the HBM, and Figure 11 shows the current waveform it generates when discharged into a lowimpedance state. 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. ±35kV ESD Protection 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 MAX14782E have extra protection against static electricity. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, the MAX14782E keeps working without latch-up or damage. ESD protection can be tested in various ways. The transmitter outputs and receiver inputs of the MAX14782E are characterized for protection to the following limits: RC 1MΩ CHARGE CURRENTLIMIT RESISTOR HIGHVOLTAGE DC SOURCE CS 100pF RD 1.5kΩ Figure 10. Human Body ESD Test Model www.maximintegrated.com ● ±12kV using the Contact Discharge method specified in IEC 61000-4-2 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 (HBM) 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 MAX14782E helps in designing equipment to meet IEC 61000-4-2 without the need for additional ESD protection components. The major difference between tests done using the HBM and IEC 61000-4-2 is higher peak current in IEC 610004-2 because series resistance is lower in the IEC 610004-2 model. Hence, the ESD withstand voltage measured to IEC 61000-4-2 is generally lower than that measured using the HBM. IP 100% 90% DISCHARGE RESISTANCE STORAGE CAPACITOR ● ±20kV using the Air-Gap Discharge method specified in IEC 61000-4-2 IR PEAK-TO-PEAK RINGING (NOT DRAWN TO SCALE) AMPERES DEVICE UNDER TEST 36.8% 10% 0 0 tRL TIME tDL CURRENT WAVEFORM Figure 11. Human Body Current Waveform Maxim Integrated │ 14 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Figure 12 shows the IEC 61000-4-2 model, and Figure 13 shows the current waveform for IEC 61000-4-2 ESD Contact Discharge test. Applications Information RE and DE can be connected together and driven simultaneously. The MAX14782E is 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 800ns (max), the device is guaranteed to enter shutdown. Driver Output Protection Typical Applications Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus connection. The first, a current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range. The second, a thermal-shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature exceeds +160°C (typ). The MAX14782E transceiver is designed for bidirectional data communications on multipoint bus transmission lines. Figure 14 shows a typical network application circuit. To minimize reflections, terminate the line at both ends with its characteristic impedance and keep stub lengths off the main line as short as possible. Low-Power Shutdown Mode Low-power shutdown mode is initiated by bringing RE high and DE low. In shutdown, the devices draw less than 10µA of supply current. RC 50MΩ TO 100MΩ HIGHVOLTAGE DC SOURCE CS 150pF I 100% 90% DISCHARGE RESISTANCE IPEAK CHARGE CURRENTLIMIT RESISTOR RD 330Ω DEVICE UNDER TEST STORAGE CAPACITOR 10% tR = 0.7ns TO 1ns t 30ns 60ns Figure 12. IEC 61000-4-2 ESD Test Model Figure 13. IED 61000-4-2 ESD Generator Current Waveform 120Ω DI DE B D D DI DE RO 120Ω B A B A B A A R R RE R R D MAX14782E DI RO RE D DE RO RE DI DE RO RE Figure 14. Typical Half-Duplex RS-485 Network www.maximintegrated.com Maxim Integrated │ 15 MAX14782E Chip Information PROCESS: BiCMOS www.maximintegrated.com 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 8 SO S8+4 21-0041 90-0096 8 TDFN-EP T833+2 21-0137 90-0059 8 µMAX U8+1 21-0036 90-0092 Maxim Integrated │ 16 MAX14782E 500Kbps 3.3V to 5V RS-485/RS-422 Transceiver with ±35kV HBM ESD Protection Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 8/13 Initial release — For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2013 Maxim Integrated Products, Inc. │ 17