3PEAK TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Features Description Exceeds Requirements of EIA-485 Standard The TP8485E are 3V~5.5V powered transceivers that Hot Plug Circuitry - Tx and Rx Outputs Remain meet the RS-485 and RS-422 standards for balanced Three-State During Power-up/Power-down communication. Driver outputs and receiver inputs are protected against 18kV ESD strikes without latch-up. Data Rate: Up to 250 kbps Full Fail-safe (Open, Short, Terminated) output voltages (2.5V min/5Vcc), into the RS-485 required Receivers 54 load, for better noise immunity, or to allow up to eight Up to 256 Nodes on a Bus (1/8 unit load) 120 terminations in "star" topologies. These devices Wide Supply Voltage 3V to 5.5V have very low bus currents so they present a true "1/8 unit SOIC-8 Package for Backward Compatibility load" to the RS-485 bus. This allows up to 256 Bus-Pin Protection: Transmitters in this family deliver exceptional differential transceivers on the network without using repeaters. Receiver (Rx) inputs feature a "Full Fail-Safe" design, - 18 kV HBM protection which ensures a logic high Rx output if Rx inputs are floating, shorted, or on a terminated but undriven bus. Rx Applications outputs feature high drive levels - typically 25mA @ VOL E-Metering Networks interfaces). Industrial Automation HVAC Systems Process Control DMX512-Networks Battery-Powered Applications = 1V (to ease the design of optocoupled isolated The TP8485E is available in an SOIC-8 and MSOP-8 package, and is characterized from -40C to 125C. 3PEAK and the 3PEAK logo are registered trademarks of 3PEAK INCORPORATED. All other trademarks are the property of their respective owners. Exceptional Tx Drives Up To 256 Loads While Pin Configuration (Top View) 1 8 VCC /RE 2 7 B/Z DE 3 6 A/Y 5 GND D 4 Driver Output Current (mA) 100 TP8485E 8-Pin SOIC/MSOP -S and -V Suffixes R Still Delivering 2.5V VOD 90 80 +25 70 RD=15 60 +85 50 RD=54 40 RD=20 30 20 RD=100 10 0 0.5 1 1.5 2 2.5 3 3.5 Differential Output Voltage (V) www.3peakic.com.cn Rev. C 1 TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Order Information Model Name Order Number Package Transport Media, Quantity Marking Information TP8485E TP8485E-SR 8-Pin SOIC Tape and Reel, 4,000 TP8485E TP8485E TP8485E-VR 8-Pin MSOP Tape and Reel, 3,000 TP8485E DRIVER PIN FUNCTIONS INPUT ENABLE D DE OUTPUTS A DESCRIPTION B NORMAL MODE H H H L Actively drives bus High L H L H Actively drives bus Low X L Z Z Driver disabled X OPEN Z Z Driver disabled by default OPEN H H L Actively drives bus High RECEIVER PIN FUNCTIONS DIFFERENTIAL INPUT ENABLE OUTPUT VID = VA - VB /RE R DESCRIPTION NORMAL MODE 2 VIT+ < VID L H Receive valid bus High VIT- < VID < VIT+ L ? Indeterminate bus state VID < VIT- L L Receive valid bus Low X H Z Receiver disabled X OPEN Z Receiver disabled Open, short, idle Bus L H Indeterminate bus state Rev. C www.3peakic.com.cn TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Absolute Maximum Ratings VDD to GND.......................................................................................................................................-0.3V to +7V Input Voltages DI, DE, RE..................................................................................................................-0.3V to (VCC + 0.3V) Input/Output Voltages A/Y, B/Z, A, B, Y, Z...................................................................................................... -9V to +14V A/Y, B/Z, A, B, Y, Z (Transient Pulse Through 100, Note 1)....................................................................................................................... 100V RO............................................................................................................................ -0.3V to (VCC +0.3V) Short Circuit Duration Y, Z............................................................................................................................Continuous ESD Rating................................................................................................................. See Specification Table Recommended Operating Conditions Note 2 Supply Voltage..............................................................................................................3V~5.5V Temperature Range.......................................................................................................-40C to +125C Bus Pin Common Mode Voltage Range ............................................................................ -8V to +13V Thermal Resistance, JA (Typical) 8-Pin SOIC Package ......................................................................................................158C/W Maximum Junction Temperature (Plastic Package) ..............................................................+150C Maximum Storage Temperature Range ............................................................................ -65C to +150C Note 1: Tested according to TIA/EIA-485-A, Section 4.2.6 (100V for 15s at a 1% duty cycle). Note 2: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and result in failures not covered by warranty. www.3peakic.com.cn Rev. C 3 TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Electrical Characteristics Test Conditions: VCC = 5V, Over operating free-air temperature range(unless otherwise noted) PARAMETER CONDITIONS RL = 60 |VOD| Driver differential-output voltage magnitude See Figure 1B RL = 54 with VA or VB from -7 to +12 V, VCC = 5V (RS-485) RL = 54 with VA or VB from -7 to +12 V, VCC = 3V (RS-485) MIN VOC(SS) VOC Change in magnitude of driver differential-output voltage 2.1 Steady-stage common-mode output voltage Change in differential driver common-mode output voltage V 1 1.5 3 See Figure 1A -0.2 -0.002 V V VOC(PP) 0.5 COD Differential output capacitance 8 VIT+ Positive-going receiver differential-input voltage threshold VIT- Negative-going receiver differential-input voltage threshold VHYS(1) Receiver differential-input voltage threshold hysteresis (VIT+ - VIT- ) VIH Logic Input High Voltage DI, DE, RE VIL Logic Input Low Voltage DI, DE, RE VOH Receiver high-level output voltage IOH= -8 mA VOL Receiver low-level output voltage IOL= 8 mA II Driver input, driver enable and receiver enable input current IOZ Receiver high-impedance output current |IOS| II 4 V 0.05 See Figure 1A Peak-to-peak driver common-mode output voltage ICC 0.2 VCC/2 Center of two 27 load resistors UNITS 2.5 See Figure 1A RL = 54 , CL=50 pF, VCC = 5V MAX 2.6 RL = 100 (RS-422) |VOD| TYP pF -40 -200 mV 110 mV 2 V 0.4 4 mV 4.5 V V 0.2 0.4 V -2 0.01 2 A VO = 0 V or VCC, /RE at VCC -2 0.01 2 A Driver short-circuit output current IOS with VA or VB from -7 to +12 V 75 80 115 mA Bus input current(driver disabled) VCC = 4.5 to 5.5 V or VCC = 0 V, DE at 0 V 100 150 VI= -7 V -150 -80 Driver and receiver enabled DE = VCC, /RE = GND, No LOAD 695 900 Driver enabled, receiver disabled DE = VCC, /RE = VCC, No LOAD 270 350 Driver disabled, receiver enabled DE = GND, /RE = VCC, No LOAD 480 600 Driver and receiver disabled DE = GND, /RE = VCC, D= Vcc No LOAD 1.4 5 Supply current(quiescent) Rev. C VI= 12 V A A www.3peakic.com.cn TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Switching CHARACTERISTICS PARAMETER CONDITIONS MIN TYP MAX UNITS DRIVER tr, tf Driver differential-output rise and fall times tPHL, tPLH Driver propagation delay tSK(P) tPHZ, tPLZ tPHZ, tPLZ 620 RL = 54 , CL=50pF See Figure 2 Driver pulse skew, |tPHL - tPLH| 23 Driver disable time Driver enable time ns 340 250 Receiver enabled See Figure 3 Receiver disabled ns 562 ns 562 RECEIVER tr, tf Receiver output rise and fall times tPHL, tPLH Receiver propagation delay time 12.4 960 CL=15 pF See Figure 5 ns tSK(P) Receiver pulse skew, |tPHL - tPLH| 40 tPHZ, tPLZ Receiver disable time 7 tPZL, tPZH Driver enabled See Figure 6 70 Driver disabled See Figure 6 989 ns Receiver enable time ns ESD RS-485 Pins (A, Y, Human Body Model, From Bus Pins to B, Z, A/Y, GND 18 kV 4 kV B/Z) All Other Human Body Model, per MIL-STD-883 Pins www.3peakic.com.cn Rev. C 5 TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Test Circuits and Waveforms Vcc RL/2 DE Vcc Z DI D Z DI VOD Y 375 DE D VOD RL=60 Y RL/2 VOC 375 FIGURE 1A. VOD AND VOC FIGURE 1B. VOD WITH COMMON MODE LOAD FIGURE 1. DC DRIVER TEST CIRCUITS 3V CL=100pF Vcc DI DE DI 1.5V 1.5V 0V tPLH Z D Y RDIFF CL=100pF OUT(Z) VOH OUT(Y) VOL DIFF OUT(Y-Z) SIGNAL GENERATOR tPHL 90% +VOD 90% 10% tR 10% tF -VOD SKEW=|tPLH-tPHL| FIGURE 2A. TEST CIRCUIT FIGURE 2B. MEASUREMENT POINTS FIGURE 2. DRIVER PROPAGATION DELAY AND DIFFERENTIAL TRANSITION TIMES DE DI Z 500 D SIGNAL GENERATOR Y SW CL VCC GND DE PARAMETER OUTPUT RE DI 3V NOTE 10 CL tZH,tZH(SHDN) (pF) NOTE 10 SW OUT(Y,Z) tHZ Y/Z X 1/0 GND 15 tLZ Y/Z X 0/1 VCC 15 tZL,tZL(SHDN) tZH Y/Z 0 1/0 GND 100 NOTE 10 tZL Y/Z 0 0/1 VCC 100 tZH(SHDN) Y/Z 1 1/0 GND 100 tZL(SHDN) Y/Z 1 0/1 VCC 100 FIGURE 3A. TEST CIRCUIT OUT(Y,Z) 1.5V 1.5V 0V tHZ OUTPUT HIGH VOL-0.5V VOH 2.3V 0V tLZ 2.3V VCC VOL+0.5V VOL OUTPUT LOW FIGURE 3B. MEASUREMENT POINTS FIGURE 3. DRIVER ENABLE AND DISABLE TIMES 6 Rev. C www.3peakic.com.cn TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Test Circuits and Waveforms(continue) Vcc DE DI + Z 60 D CD Y 3V VOD - DI 0V SIGNAL GENERATOR DIFF OUT(Y-Z) FIGURE 4A. TEST CIRCUIT +VOD -VOD 0V FIGURE 4B. MEASUREMENT POINTS FIGURE 4. DRIVER DATA RATE 0V RE B R A RO 15pF +1.5V A 0V 0V -1.5V tPLH SIGNAL GENERATOR tPHL VCC RO FIGURE 5A. TEST CIRCUIT 1.5V 1.5V 0V FIGURE 5B. MEASUREMENT POINTS FIGURE 5. RECEIVER PROPAGATION DELAY AND DATA RATE SIGNAL GENERATOR RE B GND A R 1k RO VCC SW GND 15pF NOTE 10 RE PARAMETER tHZ DE 1 A +1.5V SW tZH,tZH(SHDN) GND NOTE 10 RO tLZ 1 -1.5V VCC tZH 1 +1.5V GND tZL,tZL(SHDN) tZL 1 -1.5V VCC NOTE 10 tZH(SHDN) tZL(SHDN) 0 0 +1.5V -1.5V GND VCC FIGURE 6A. TEST CIRCUIT RO 3V 1.5V 1.5V 0V tHZ OUTPUT HIGH 1.5V VOH-0.5V VOH 0V tLZ 1.5V VCC VOL+0.5V VOL OUTPUT LOW FIGURE 6B. MEASUREMENT POINTS FIGURE 6. RECEIVER ENABLE AND DISABLE TIMES www.3peakic.com.cn Rev. C 7 TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Detailed Description RS-485 and RS-422 are differential (balanced) data transmission standards used for long haul or noisy environments. RS-422 is a subset of RS-485, so RS-485 transceivers are also RS-422 compliant. RS-422 is a point-to-multipoint (multidrop) standard, which allows only one driver and up to 10 (assuming one unit load devices) receivers on each bus. RS-485 is a true multipoint standard, which allows up to 32 one unit load devices (any combination of drivers and receivers) on each bus. To allow for multipoint operation, the RS-485 specification requires that drivers must handle bus contention without sustaining any damage. Another important advantage of RS-485 is the extended common mode range (CMR), which specifies that the driver outputs and receiver inputs withstand signals that range from +12V to -7V. RS-422 and RS-485 are intended for runs as long as 4000', so the wide CMR is necessary to handle ground potential differences, as well as voltages induced in the cable by external fields. Receiver (Rx) Features TP8485E utilize a differential input receiver for maximum noise immunity and common mode rejection. Input sensitivity is better than 200mV, as required by the RS-422 and RS-485 specifications. Rx outputs feature high drive levels (typically 25mA @ VOL = 1V) to ease the design of optically coupled isolated interfaces. Receiver input resistance of 100k surpasses the RS-422 specification of 4k, and is eight times the RS-485 "Unit Load (UL)" requirement of 12k minimum. Thus, these products are known as "one-eighth UL" transceivers, and there can be up to 256 of these devices on a network while still complying with the RS-485 loading specification. Rx inputs function with common mode voltages as great as 7V outside the power supplies (i.e., +12V and -7V), making them ideal for long networks where induced voltages are a realistic concern. All the receivers include a "full fail-safe" function that guarantees a high level receiver output if the receiver inputs are unconnected (floating), shorted together, or connected to a terminated bus with all the transmitters disabled. Receivers easily meet the data rates supported by the corresponding driver, and all receiver outputs are three-stable via the active low RE input. Driver (Tx) Features TP8485E driver is a differential output device that delivers at least 2.5V across a 54 load (RS-485), and at least 2.8V across a 100 load (RS-422). The drivers feature low propagation delay skew to maximize bit width, and to minimize EMI, and all drivers are three-stable via the active high DE input. Full Fail-Safe All the receivers include a "full fail-safe" function that guarantees a high level receiver output if the receiver inputs are unconnected (floating), shorted together, or connected to a terminated bus with all the transmitters disabled. Receivers easily meet the data rates supported by the corresponding driver, and all receiver outputs are three-statable via the active low RE input. Hot Plug Function When a piece of equipment powers up, there is a period of time where the processor or ASIC driving the RS-485 control lines (DE, RE) is unable to ensure that the RS-485 Tx and Rx outputs are kept disabled. If the equipment is connected to the bus, a driver activating prematurely during power-up may crash the bus. To avoid this scenario, the TP8485E devices incorporate a "Hot Plug" function. Circuitry monitoring VCC ensures that, during power-up and power-down, the Tx and Rx outputs remain disabled, regardless of the state of DE and RE, if VCC is less than ~2.5V. This gives the processor/ASIC a chance to stabilize and drive the RS-485 control lines to the proper states. 8 Rev. C www.3peakic.com.cn TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver COMPETITOR FIGURE 8. HOT PLUG PERFORMANCE (TP8485E) vs Competitor WITHOUT HOT PLUG CIRCUITRY Transient Protection The bus terminals of the TP8485E transceiver family possess on-chip ESD protection against 18 kV HBM. The International Electrotechnical Commision (IEC) ESD test is far more severe than the HBM ESD test. The 50% higher charge capacitance, CS, and 78% lower discharge resistance, RD of the IEC model produce significantly higher discharge currents than the HBM model. As stated in the IEC 61000-4-2 standard, contact discharge is the preferred transient protection test method. Although IEC air-gap testing is less repeatable than contact testing, air discharge protection levels are inferred from the contact discharge test results. Figure 9. HBM and IEC-ESD Models and Currents in Comparison (HBM Values in Parenthesis) The on-chip implementation of IEC ESD protection significantly increases the robustness of equipment. Common discharge events occur because of human contact with connectors and cables. Designers may choose to implement protection against longer duration transients, typically referred to as surge transients. Figure 9 suggests two circuit designs providing protection against short and long duration surge transients, in addition to ESD and Electrical Fast Transients (EFT) transients. Table 1 lists the bill of materials for the external protection devices. EFTs are generally caused by relay-contact bounce or the interruption of inductive loads. Surge transients often result from lightning strikes (direct strike or an indirect strike which induce voltages and currents), or the switching of power systems, including load changes and short circuits switching. These transients are often encountered in industrial environments, such as factory automation and power-grid systems. Figure 10 compares the pulse-power of the EFT and surge transients with the power caused by an IEC ESD transient. In the diagram on the left of Figure 10, the tiny blue blip in the bottom left corner represents the power of a 10-kV ESD www.3peakic.com.cn Rev. C 9 TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver transient, which already dwarfs against the significantly higher EFT power spike, and certainly dwarfs against the 500-V surge transient. This type of transient power is well representative of factory environments in industrial and process automation. The diagram on the fright of Figure 10 compares the enormous power of a 6-kV surge transient, most likely occurring in e-metering applications of power generating and power grid systems, with the aforementioned 500-V surge transient. Figure 10. Power Comparison of ESD, EFT, and Surge Transients In the case of surge transients, high-energy content is signified by long pulse duration and slow decaying pulse Power The electrical energy of a transient that is dumped into the internal protection cells of the transceiver is converted into thermal energy. This thermal energy heats the protection cells and literally destroys them, thus destroying the transceiver. Figure 11 shows the large differences in transient energies for single ESD, EFT, and surge transients as well as for an EFT pulse train, commonly applied during compliance testing. Figure 11. Comparison of Transient Energies 10 Rev. C www.3peakic.com.cn TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Table 1. Bill of Materials Device Function Order Number Manufacturer 485 5-V, 250-kbps RS-485 Transceiver TP8485E R1, R2 10-, Pulse-Proof Thick-Film Resistor CRCW0603010RJNEAHP Vishay TVS Bidirectional 400-W Transient Suppressor CDSOT23-SM712 Bourns TBU1, TBU2 Bidirectional TBU-CA-065-200-WH Bourns MOV1, MOV2 200mA Transient Blocking Unit 200-V, MetalOxide Varistor MOV-10D201K Bourns 485 B A Figure 12. 485 3PEAK B A Transient Protections Against ESD, EFT, and Surge Transients The left circuit shown in Figure 12 provides surge protection of 500-V transients, while the right protection circuits can withstand surge transients of 5 kV www.3peakic.com.cn Rev. C 11 TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Typical Performance Characteristics 90 4 Differential Output Voltage (V) 4.5 Driver Output Current (mA) 100 80 +25 70 RD=15 60 +85 50 RD=54 40 RD=20 30 20 RD=100 10 0 RDIFF=100 3.5 RDIFF=54 3 2.5 2 1.5 1 0.5 0 0.5 1 1.5 2 2.5 3 3.5 -40 -20 0 20 FIGURE 13. DRIVER OUTPUT CURRENT vs 80 100 120 140 vs TEMPERATURE 700 600 Y OR Z = LOW DE=Vcc,RE=X 500 Icc (A) Output Current (mA) 60 FIGURE 14. DRIVER DIFFERENTIAL OUTPUT VOLTAGE DIFFERENTIAL OUTPUT VOLTAGE 100 90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 -60 40 Temperature ( Differential Output Voltage (V) Y OR Z = HIGH 400 300 200 DE=GND,RE=GND 100 0 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 -50 Output Voltage(V) FIGURE 15. DRIVER OUTPUT CURRENT vs SHORT -25 0 25 50 75 Temperature () 100 125 150 FIGURE 16. SUPPLY CURRENT vs TEMPERATURE CIRCUIT VOLTAGE 2.5 1 2 0.8 tPLH 0.7 1.5 Skew (s) Propagation Delay (s) 0.9 1 0.6 0.5 0.4 0.3 tPHL 0.5 0.2 0.1 0 0 -40 -20 0 20 40 60 80 100 120 140 Temperature ( FIGURE 17. DRIVER DIFFERENTIAL PROPAGATION DELAY vs TEMPERATURE 12 Rev. C -40 -20 0 20 40 60 80 100 120 140 Temperature () FIGURE 18. DRIVER DIFFERENTIAL SKEW vs TEMPERATURE www.3peakic.com.cn TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Typical Performance Curves FIGURE 19. DRIVER AND RECEIVER WAVEFORMS www.3peakic.com.cn VCC = 5V, TA = +25C; Unless Otherwise Specified. FIGURE 20. DRIVER WAVEFORMS Rev. C 13 TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Package Outline Dimensions SO-8 (SOIC-8) A2 C L1 A1 e E D Symbol E1 b Rev. C Dimensions In In Millimeters Inches Min Max Min Max A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 C 0.190 0.250 0.007 0.010 D 4.780 5.000 0.188 0.197 E 3.800 4.000 0.150 0.157 E1 5.800 6.300 0.228 0.248 e 14 Dimensions 1.270 TYP 0.050 TYP L1 0.400 1.270 0.016 0.050 0 8 0 8 www.3peakic.com.cn TP8485E 18K ESD Protection, Full Fail-Safe RS-485 Transceiver Package Outline Dimensions MSOP-8 Dimensions Dimensions In In Millimeters Inches Min Max Min Max A 0.800 1.200 0.031 0.047 A1 0.000 0.200 0.000 0.008 A2 0.760 0.970 0.030 0.038 b 0.30 TYP 0.012 TYP C 0.15 TYP 0.006 TYP D 2.900 e 0.65 TYP E 2.900 3.100 0.114 0.122 E1 4.700 5.100 0.185 0.201 L1 0.410 0.650 0.016 0.026 0 6 0 6 Symbol E E1 A A2 e b D 3.100 0.114 0.122 0.026 A1 R1 R L1 www.3peakic.com.cn L L2 Rev. C 15