ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ STC3485E 3.3V-Powered, ±15kV ESD-Protected, and Slew-Rate-Limited True RS-485 Transceivers General Description The STC3485E is +15 KV ESD protected, slew-rate limited, ultra lower differential line transceivers which provide full RS485 compatibility while operating from single 3.3V supply. Each part contains one driver and one receiver, which is designed for data transmission with extended common mode range (-7V to 12V). The STC3485E features slew-rate limited driver that minimizes EMI and reduces reflections caused by improperly terminated cables, allowing error-free data transmission at data rate up to 500kbps. All devices feature enhanced electrostatic discharge (ESD) protection. All transmitter outputs and receiver inputs are protected to ±15kV using IEC 1000-4-2 Air-Gap Discharge and ±15kV using the Human Body Model. Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if both inputs are open, shorted or idle. Both parts have power up/down glitch free driver outputs permit live insertion or removal of transceiver from/to data bus. The CMOS design offers significant power savings without sacrificing ruggedness against overload or ESD damage. Typical quiescent current is only 500 µA while operating and 1 µA in shutdown. The STC3485E are fully specified over the commercial an extended industrial temperature range and are available in 8-pin and DIP packages. Applications Telecommunications Low-Power RS-485 Transceivers Integrated Services Digital Networks Transceivers for EMI-Sensitive Applications Packet Switching Features ESD Protection for RS-485 I/O Pins ±15kV— Human Body Model ±15kV— IEC 1000-4-2, Air-Gap Discharge Operate from a Single 3.3V supply Interoperable with +5V Logic Slew-Rate Limited for Errorless Data Transmission 1 µA Low-Current Shutdown Mode –7V to +12V Common-Mode Input Voltage Range Allows up to 256 Transceivers on the Bus Thermal Shutdown Current-Limiting for Driver Overload Protection Ordering Information PART TEMP. RANGE PIN-PACKAGE STC3485EESA -40°C to +85°C 8 SO STC3485EEPA -40°C to +85°C 8 Plastic DIP ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Ｐａｇｅ ｏｆ １１ １ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ Selector Guide PART GUARANTEED SUPPLY DATA RATE VOLTAGE NUMBER STC3485E (Mbps) (V) 0.5 3.0 to 3.6 SLEW-RATE LIMITED DRIVER/ SHUTDOWN ±15kV RECEIVER CURRENT ESD ENABLE (µA) PROTECTION Yes 1 Yes Yes PIN COUNT 8 Absolute Maximum Ratings Supply Voltage (VCC) … … … … … … … … … … … … … … … … … … 5V Control Input Voltage (/RE, DE) … … … … … … … … … … … -0.3V to 5V Driver Input Voltage (DI) … … … … … … … … … … … … … … -0.3V to 5V Driver Output Voltage (A, B) … … … … … … … … … … … … -7V to 12V Receiver Input Voltage (A, B) … … … … … … … … … … … … -7V to 12V Receiver Output Voltage (RO) … … … … … … … -0.3V to (VCC + 0.3V) 8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) … … … … 727mW 8-Pin SO (derate 5.88mW/°C above +70°) … … … … … … … … 471mW Operating Temperature Ranges STC3485EE_ _ … … … … … … … … … … … … … … … -40°C to +85°C Storage Temperature Range… … … … … … … … … … -65°C to +160°C Lead Temperature (soldering, 10sec) … … … … … … … … … … +300°C Continuous Power Dissipation (TA = +70°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. DC Electrical Characteristics (VCC = 3.3V ±0.3V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C) PARAMETER Differential Driver Output SYMBOL VOD CONDITIONS MIN RL = 54O ? (RS-485), Figure 2 1.2 RL = 60O ? (RS-485), VCC = 3.3V, Figure3 1.2 TYP MAX UNITS V Change in Magnitude of Driver Differential Output Voltage for Complementary Output ?VOD RL = 54O? or 100O, Figure 2 VOC RL = 54O? or 100O, Figure 2 ?VOC RL = 54Oor 100O, Figure 2 Input High Voltage VIH DE, DI, /RE Input Low Voltage VIL DE, DI, /RE Logic Input Current IIN1 0.2 V States (Note 1) Driver Common-Mode Output Voltage 2 V Change in Magnitude of Common-Mode Output Voltage 0.2 V (Note 1) Input Current (A, B) Receiver Differential IIN2 2.0 V DE, DI, /RE 0.8 V ±2 µA DE = 0V, VIN = 12V 1.0 VCC = 0V or 3.6V VIN = -7V -0.8 mA VTH -7V≤VCM≤12V Receiver Input Hysteresis ?VTH VCM = 0V Receiver Output High Voltage VOH IOUT = -1.5mA, VID = 200mV, Figure 4 Receiver Output Low Voltage VOL IOUT = 2.5mA, VID = 200mV, Figure 4 0.4 V IOZR VCC = 3.6V, 0V≤VOUT≤VCC ±1 µA Receiver Input Resistance RIN -7V≤VCM≤12V Supply Voltage Range VCC Supply Current ICC Threshold Voltage Three-State (High Impedance) Output Current at Receiver Supply Current in Shutdown Mode ISHDN Driver Short-Circuit Output Current IOSD Receiver Short-Circuit Output Current IOSR ESD Protection for A, B ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ -0.2 -0.05 20 mV VCC - 0.4 V 96 kO 3.0 3.6 No load, DE = VCC, /RE = 0V or VCC 0.6 1.2 DI = 0V or VCC DE = 0V, /RE = 0V 0.5 1.0 DE = 0V, /RE = VCC, DI = VCC or 0V 1.0 -250 VOUT = 12V 250 Human Body Model IEC 1000-4-2 Air Discharge ±8 V mA µA VOUT = -7V 0V≤VRO≤VCC V ±60 ±15 ±15 Ｐａｇｅ ｏｆ １１ ２ mA mA kV ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ Receiver Switching Characteristics (VCC = 3.3V, TA = +25°C) SYMBOL PARAMETER CONDITIONS Maximum Data Rate MIN TYP MAX UNITS 0.5 Mbps Driver Differential Output Delay tDD RL = 60O, Figure 5 600 900 1400 ns Driver Differential Output Transition Time tTD RL = 60O, Figure 5 400 740 1200 ns Driver Propagation Delay, Low-to-High Level tPLH RL = 27O, Figure 6 700 930 1500 ns Driver Propagation Delay, High-to-Low Level tPHL RL = 27O, Figure 6 700 930 1500 ns |tPLH - tPHL| Driver Propagation Delay Skew (Note 2) tPDS RL = 27O, Figure 6 ±50 Driver Output Enable Time to Low Level tPZL RL = 110O, Figure 8 900 1300 Driver Output Enable Time to High Level tPZH RL = 110O, Figure 7 600 800 ns Driver Output Disable Time from High Level tPHZ RL = 110O, Figure 7 50 80 ns Driver Output Disable Time from Low Level tPLZ RL = 110O, Figure 8 50 80 ns Driver Output Enable Time from Shutdown to Low Level tPSL RL = 110O, Figure 8 1.9 2.7 µs Driver Output Enable Time from Shutdown to High Level tPSH RL = 110O, Figure 7 2.2 3.0 µs ns DRIVER-OUTPUT ENABLE/DISABLE TIMES ns Receiver Switching Characteristics (VCC = +3.3V, TA = +25°C.) PARAMETER Time to Shutdown Receiver Propagation Delay, Low-to-High Level Receiver Propagation Delay, High-to-Low Level |tPLH - tPHL| Receiver Propagation-Delay Skew Receiver-Output Enable Time to Low Level Receiver-Output Enable Time to High Level Receiver-Output Disable Time from High Level Receiver-Output Disable Time from Low Level Receiver-Output Enable Time from Shutdown to Low Level Receiver-Output Enable Time SYMBOL CONDITIONS MIN TYP MAX tSHDN (Note 3) 80 190 300 VID = 0 to 3.0V, CL = 15pF, Figure 9 25 62 90 STC3485E 25 75 120 VID = 0 to 3.0V, CL = 15pF, Figure 9 25 62 90 STC3485E 25 75 120 tRPLH tRPHL tPRZH tPRHZ tPRLZ tPRSL tPRSH from Shutdown to High Level ns ns ns VID = 0 to 3.0V, CL = 15pF, Figure 9 6 ±10 STC3485E 12 ±20 25 50 ns 25 50 ns 25 45 ns 25 45 ns 720 1400 ns 720 1400 ns tRPDS tPRZL UNITS ns CL = 15pF, Figure 10, STC3485E CL = 15pF, Figure 10, STC3485E CL = 15pF, Figure 10, STC3485E CL = 15pF, Figure 10, STC3485E CL = 15pF, Figure 12, STC3485E CL = 15pF, Figure 10, STC3485E Note 1: ? VOD and ? VOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 2: Measured on |tPLH (Y) - tPHL (Y)| and |tPLH (Z) - tPHL (Z)|. Note 3: The transceivers are put into shutdown by bringing /RE high and DE low. If the inputs are in this state for less than 80ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 300ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section. ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Ｐａｇｅ ｏｆ １１ ３ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ Typical Operating Characteristics (VCC = 3.3V, TA = +25°C, unless otherwise noted.) ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ ｖｓ． ＲＥＣＥＩＶＥＲ ＯＵＴＰＵＴ ＬＯＷ ＶＯＬＴＡＧＥ ＲＥＣＥＩＶＥＲ ＯＵＴＰＵＴ ＨＩＧＨ ＶＯＬＴＡＧＥ ｖｓ．ＴＥＭＰＥＲＡＴＵＲＥ ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ ｖｓ． ＲＥＣＥＩＶＥＲ ＯＵＴＰＵＴ ＨＩＧＨ ＶＯＬＴＡＧＥ ２５ －２０ ３．３０ －１６ ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ（ｍＡ） ２０ ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ（ｍＡ） ＯＵＴＰＵＴ ＨＩＧＨＶＯＬＴＡＧＥ（Ｖ） －１８ １５ １０ －１４ －１２ －１０ －８ －６ ５ －４ ０．５ １．０ １．５ ２．０ ２．５ ３．５ ３．０ ０ ＯＵＴＰＵＴ ＬＯＷ ＶＯＬＴＡＧＥ （Ｖ） １．０ １．５ ２．０ ２．５ ３．５ ３．０ ９０ ０．６ ０．５ ０．４ ０．３ ０．２ ６０ ５０ ４０ ３０ ２０ １０ ０ ０ ４０ ６０ ８０ １００ ０ Ｔ Ｅ Ｍ Ｐ Ｅ Ｒ Ａ Ｔ Ｕ Ｒ Ｅ （℃） ０．５ １．０ １．５ ２．０ ２．５ ６０ ４０ ８０ ２．４ ２．３ ２．２ ２．１ ２．０ １．９ １．８ １．７ １．６ －４０ ３．５ ３．０ ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ ｖｓ． ＤＲＩＶＥＲ ＯＵＴＰＵＴ ＬＯＷ ＶＯＬＴＡＧＥ －２０ ２０ ０ ４０ ６０ ８０ Ｔ Ｅ Ｍ Ｐ Ｅ Ｒ Ａ Ｔ Ｕ Ｒ Ｅ （℃） ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ ｖｓ． ＤＲＩＶＥＲ ＯＵＴＰＵＴ ＨＩＧＨ ＶＯＬＴＡＧＥ －１００ １５０ －８０ ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ（ｍＡ） １２５ １００ ７５ ５０ －６０ －４０ －２０ ２５ ０ ０ ２ ０ ４ ６ ８ １０ １２ －７ －６ －５ －４ －３ －２ －１ ＯＵＴＰＵＴ ＬＯＷ ＶＯＬＴＡＧＥ（Ｖ） ０ １ ２ ４ ３ ５ ＯＵＴＰＵＴ ＨＩＧＨ ＶＯＬＴＡＧＥ（Ｖ） ＳＵＰＰＬＹ ＣＵＲＲＥＮＴ ｖｓ．ＴＥＭＰＥＲＡＴＵＲＥ ＳＨＵＴＤＯＷＮ ＣＵＲＲＥＮＴ ｖｓ．ＴＥＭＰＥＲＡＴＵＲＥ １００ １．２ ９０ ８０ ＳＨＵＴＤＯＷＮ ＣＵＲＲＥＮＴ（ｎＡ） ＳＵＰＰＬＹ ＣＵＲＲＥＮＴ（ｍＡ） １．１ １．０ ０．９ ７０ ６０ ５０ ４０ ３０ ２０ ０．８ １０ ０．７ ０ －４０ －２０ ０ ２０ ４０ ６０ ８０ １００ Ｔ Ｅ Ｍ Ｐ Ｅ Ｒ Ａ Ｔ Ｕ Ｒ Ｅ （℃） ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ １００ ２．５ ＤＩＦＦＥＲＥＮＴＩＡＬ ＯＵＴＰＵＴ ＶＯＬＴＡＧＥ（Ｖ） １７５ ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ（ｍＡ） ２０ ２．６ ７０ ０．１ ２０ ０ ＤＲＩＶＥＲ ＤＩＦＦＥＲＥＮＴＩＡＬ ＯＵＴＰＵＴ ＶＯＬＴＡＧＥ ｖｓ．ＴＥＭＰＥＲＡＴＵＲＥ ８０ ０ －２０ Ｔ Ｅ Ｍ Ｐ Ｅ Ｒ Ａ Ｔ Ｕ Ｒ Ｅ （℃） ＤＩＦＦＥＲＥＮＴＩＡＬ ＯＵＴＰＵＴ ＶＯＬＴＡＧＥ（Ｖ） １００ ０．７ ＯＵＴＰＵＴ ＶＯＬＴＡＧＥ（ｍＡ） ＯＵＴＰＵＴ ＬＯＷ ＶＯＬＴＡＧＥ（Ｖ） ０．５ ＤＲＩＶＥＲ ＯＵＴＰＵＴ ＣＵＲＲＥＮＴ ｖｓ． ＤＩＦＦＥＲＥＮＴＩＡＬ ＯＵＴＰＵＴ ＶＯＬＴＡＧＥ ０．８ －２０ ３．１０ ＯＵＴＰＵＴ ＨＩＧＨ ＶＯＬＴＡＧＥ （Ｖ） ＲＥＣＥＩＶＥＲ ＯＵＴＰＵＴ ＬＯＷ ＶＯＬＴＡＧＥ ｖｓ．ＴＥＭＰＥＲＡＴＵＲＥ －４０ ３．１５ ３．００ －４０ ０ ０ ３．２０ ３．０５ －２ ０ ３．２５ －４０ －２０ ０ ２０ ４０ ６０ ８０ Ｔ Ｅ Ｍ Ｐ Ｅ Ｒ Ａ Ｔ Ｕ Ｒ Ｅ （℃） Ｐａｇｅ ｏｆ １１ ４ １００ １００ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ Pin Description PIN NAME 1 RO 2 /RE FUNCTION Receiver Output. If A > B by -50mV, RO will be high; if A < B by 200mV, RO will be low. Receiver Output Enable. RO is enabled when RE is low; RO is high impedance when RE is high. If RE is high and DE is low, the device will enter a low-power shutdown mode. Driver Output Enable. The driver outputs are enabled by bringing DE high. They are high impedance 3 when DE is low. If /RE is high and DE is low, the device will enter a low-power shutdown mode. If the DE driver outputs are enabled, the parts function as line drivers. While they are high impedance, they function as line receivers if /RE is low. 4 DI 5 6 7 8 GND Driver Input. A low on DI forces output B high and output A low. Similarly, a high on DI forces output B low and output A high. Ground A Noninverting Receiver Input and Noninverting Driver Output B Inverting Receiver Input and Inverting Driver Output Positive Supply: 3.0V≤VCC≤3.6V VCC ＴＯＰ ＶＩＥＷ ＳＴＣ３４８５Ｅ ８ Ｖｃｃ ＲＯ １ ＲＥ ２ ７ Ｂ ＲＥ ２ ７ Ｂ ＤＥ ３ ６ Ａ ＤＥ ３ ６ ＲＯ １ Ｒ ＤＩ ４ Ｄ ＤＩ ４ ５ ＧＮＤ ＤＥ ８ Ｖｃｃ Ｒ Ｒｔ ＤＩ Ｒｔ Ａ ５ ＧＮＤ Ｄ Ｄ Ｂ Ａ ＳＯ／ＤＩＰ ＲＯ Ｒ ＲＥ Figure 1. STC3485E Pin Configuration and Typical Operating Circuit ３７５ Ω ＲＬ ２ Ｄ ＲＬ ２ ＶＣＣ Ｄ ＶＤＤ ＲＬ ＶＣＣ ＶＣＣ Figure 2. Driver VOD and VOC ＶＩＤ ＶＣＭ＝ －７Ｖ ｔｏ ＋１２Ｖ ＶＤＤ ３７５ Ω Figure 3. Driver VOD with Varying Common-Mode Voltage Ｒ ＯＶ ＶＯＬ ＩＣＬ ＶＯＨ （＋） ＩＯＨ （－） Figure 4. Receiver VOH and VOL ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Ｐａｇｅ ｏｆ １１ ５ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ ３Ｖ ＩＮ １．５Ｖ １．５Ｖ ＣＬ ０Ｖ Ｄ ＧＥＮＥＲＡＴＯＲ （Ｎ Ｏ Ｔ Ｅ ４ ） ＯＵＴ ＲＬ＝ ６０ Ω ｔＤＤ ｔＤＤ ５０ Ω ＯＵＴ ＣＬ ≈ ２．０Ｖ ９０％ ９０％ ＶＣＣ ５０％ １０％ ５０％ １０％ ≈ －２．０Ｖ Ｃ Ｌ ＝１５ｐＦ（ＮＯＴＥ ５） ｔＴＤ ｔＴＤ Figure 5. Driver Differential Output Delay and Transition Times ３Ｖ ＶＣＭ ＩＮ １．５Ｖ １．５Ｖ ＲＬ＝２７ Ω ０Ｖ Ｓ１ ｔＰＬＨ Ｄ ＧＥＮＥＲＡＴＯＲ （Ｎ Ｏ Ｔ Ｅ ４ ） ｔＰＨＬ ＯＵＴ ５０ Ω ＶＣＣ ＣＬ＝１５ｐＦ （Ｎ Ｏ Ｔ Ｅ ５ ） ＶＯＨ Ｙ ＯＵＴ ＶＤＭ ＶＯＭ ＶＯＬ ｔＰＨＬ ＶＯＭ ＝ ｔＰＬＨ Ｖ ＯＨ ＋Ｖ ＣＬ ≈ １．５Ｖ ２ ＶＯＨ Ｚ ＯＵＴ ＶＯＭ ＶＤＭ ＶＯＬ Figure 6. Driver Propagation Times ３Ｖ Ｓ１ Ｄ ０Ｖ ＯＲ ３Ｖ ＯＵＴ ＩＮ １．５Ｖ １．５Ｖ ０Ｖ ＣＬ＝１５ｐＦ （Ｎ Ｏ Ｔ Ｅ ５ ） ＲＬ＝１１０ Ω ＧＥＮＥＲＡＴＯＲ （Ｎ Ｏ Ｔ Ｅ ４ ） ｔＰＺＨ ｔＰＨＺ ５０ Ω ＶＯＨ ＶＯＭ＝ ０．２５Ｖ Ｙ ＯＵＴ Ｖ ＯＨ ＋Ｖ ＣＬ ≈ １．５Ｖ ２ ＶＯＭ ０Ｖ Figure 7. Driver Enable and Disable Times (tPZH, tPSH, tPHZ) ＶＣＣ Ｓ１ Ｄ ０Ｖ ＯＲ ３Ｖ ３Ｖ ＲＬ＝１１０ Ω ＯＵＴ ＩＮ １．５Ｖ １．５Ｖ ０Ｖ ＣＬ＝５０ｐＦ （Ｎ Ｏ Ｔ Ｅ ５ ） ＧＥＮＥＲＡＴＯＲ （Ｎ Ｏ Ｔ Ｅ ４ ） ｔＰＬＺ ｔＰＺＬ ５０ Ω ＶＣＣ ＶＯＭ ＯＵＴ ０．２５Ｖ ＶＯＬ Figure 8. Driver Enable and Disable Times (tPZL, tPSL, tPLZ) ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Ｐａｇｅ ｏｆ １１ ６ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ ３．０Ｖ ＶＩＤ ＧＥＮＥＲＡＴＯＲ （Ｎ Ｏ Ｔ Ｅ ４ ） ＯＵＴ Ｒ ＩＮ １．５Ｖ １．５Ｖ ＣＬ＝１５ｐＦ ５０ Ω ０Ｖ （ＮＯＴＥ ５） ｔ ＲＰＬＨ ｔ ＲＰＨＬ ＶＣＣ ＶＯＭ＝ １．５Ｖ ＶＣＣ ２ ＶＯＭ ＶＯＭ ＯＵＴ ０Ｖ ０Ｖ Figure 9. Receiver Propagation Delay Ｓ１ Ｓ３ １．５Ｖ ＶＣＣ １Ｋ ＶＩＤ －１．５Ｖ Ｒ Ｓ２ ＣＬ ＧＥＮＥＲＡＴＯＲ （Ｎ Ｏ Ｔ Ｅ ４ ） （ＮＯＴＥ ５） ５０ Ω Figure 10. Receiver Enable and Disable Times Note 4: The input pulse is supplied by a generator with the following characteristics: PRR = 250kHz, 50% duty cycle, tr=6.0ns, ZO = 50O. Note 5: CL includes probe and stray capacitance. Function Tables Devices with Receiver/Driver Enable Table 1. Transmitting INPUTS Table 2. Receiving OUTPUTS /RE DE DI B A X 1 1 0 0 1 0 0 1 1 0 X High-Z X High-Z X 0 1 INPUTS MODE OUTPUTS MODE /RE DE A, B RO Normal 0 X ≥?-0.05V 0 X ≤?-0.2V High-Z Normal X Inputs Open High-Z Shutdown 0 1 1 0 1 Normal Normal 0 X High-Z Shutdown ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Normal Normal Ｐａｇｅ ｏｆ １１ ７ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ Applications Information The STC3485E is low-power transceivers for RS-485 communications. The STC3485E can transmit and receive at data rates up to 500kbps. The STC3485E is half-duplex. Driver Enable (DE) and Receiver Enable (/RE) pins are included on the STC3485E. When disabled, the driver and receiver outputs are high impedance. Reduced EMI and Reflections The STC3485E is slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 11 shows the output waveform of the slew-rate-limited STC3485E transmitting a 125kHz signal, as well as the Fourier analysis of that waveform. The high-frequency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced. Low-Power Shutdown Mode A low-power shutdown mode is initiated by bringing both /RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled (high impedance). In shutdown, the devices typically draw only 1µA of supply current. For these devices, the tPSH and tPSL enable times assume the part was in the low-power shutdown mode; the tPZH and tPZL enable times assume the receiver or driver was disabled, but the part was not shut down. Figure 11. Driver Output Waveform and FFT Plot of Figure 12. STC3485E Driver Propagation Delay STC3485E Transmitting a 125kHz Signal Figure 13. STC3485E Receiver Propagation Delay Figure 14. STC3485E System Differential Voltage at 125kHz Driving 4000 ft of Cable ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Ｐａｇｅ ｏｆ １１ ８ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ Driver Output Protection Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). In addition, a thermal shutdown circuit forces the driver outputs into a high-impedance state if the die temperature rises excessively. Propagation Delay Figures 12 and 13 show the typical propagation delays. Skew time is simply the difference between the low-to-high and high-to-low propagation delay. Small driver/receiver skew times help maintain a symmetrical mark-space ratio (50% duty cycle). The receiver skew time, |tPRLH - tPRHL|, is under 10ns (20ns for the STC3485E). The driver skew times are typically under 50ns for the STC3485E. Line Length vs. Data Rate The RS-485 standard covers line lengths up to 4000 feet. Figure 13 shows the system differential voltage for parts driving 4000 feet of 26AWG twisted-pair wire at 125kHz into 120O loads. ±15kV ESD Protection As with all STC 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 STC3485E family of devices have extra protection against static electricity. STC’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, Union’s E versions keep working without latchup or damage. 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) ±15kV using IEC 1000-4-2’s Air-Gap method. Human Body Model Figure 15a shows the Human Body Model and Figure 15b shows the current waveform it generates when discharged into a low impedance. This model consists of 100pF capacitor charged to the ESD voltage of interest, which is then discharged into the test device through a 1.5kO r?esistor. 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 STC3485E family devices help 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 16a shows the IEC 1000-4-2 model, and Figure 16b 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. ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Ｐａｇｅ ｏｆ １１ ９ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ 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 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. Typical Applications The STC3485E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 1 shows typical network applications circuits. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possible. The slew-rate-limited STC3485E is more tolerant of imperfect termination. ＲＣ １Ｍ ＲＤ １５００ Ω ＣＨＡＲＧＥ－ＣＵＲＲＥＮＴ ＬＩＭＩＴ ＲＥＳＩＳＴＯＲ ＨＩＧＨ－ ＶＯＬＴＡＧＥ ＤＣ ＳＯＵＲＣＥ ＣＳ １００ｐＦ ＤＩＳＣＨＡＲＧＥ ＲＥＳＩＳＴＡＮＣＥ ＳＴＯＲＡＧＥ ＣＡＰＡＣＩＴＯＲ ＤＥＶＩＣＥ ＵＮＤＥＲ ＴＥＳＴ Figure 15a. Human Body ESD Test Model ＲＣ ５０Ｍ ｔｏ １００Ｍ ＣＨＡＲＧＥ－ＣＵＲＲＥＮＴ ＬＩＭＩＴ ＲＥＳＩＳＴＯＲ ＨＩＧＨ－ ＶＯＬＴＡＧＥ ＤＣ ＳＯＵＲＣＥ ＣＳ １５０ｐＦ Figure 15b. Human Body Current Waveform ＲＤ ３３０ Ω ＤＩＳＣＨＡＲＧＥ ＲＥＳＩＳＴＡＮＣＥ ＳＴＯＲＡＧＥ ＣＡＰＡＣＩＴＯＲ ＤＥＶＩＣＥ ＵＮＤＥＲ ＴＥＳＴ Figure 16a. IEC 1000-4-2 ESD Test Model Figure 16b. IEC 1000-4-2 ESD Generator Current Waveform ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ Ｐａｇｅ ｏｆ １１ １０ ＳＴＣ Ｉｎｔｅｒｎａｔｉｏｎａｌ Ｌｉｍｉｔｅｄ ｈｔｔｐ：／／ｗｗｗ．ｍｃｕ－ｍｅｍｏｒｙ．ｃｏｍ Package Information ＩＮＣＨＥＳ ＤＩＭ Ｄ Ａ ０°－ ８° Ａ１ ０．１０１ｍｍ ０．００４ｉｎ． Ｅ ＭＡＸ ＭＩＮ ＭＡＸ Ａ ０．０５３ ０．０６９ １．３５ １．７５ Ａ１ ０．００４ ０．０１０ ０．１０ ０．２５ Ｂ ０．０１４ ０．０１９ ０．３５ ０．４９ Ｃ ０．００７ ０．０１０ ０．１９ ０．２５ Ｅ ０．１５０ ０．１５７ ３．８０ ４．００ ｅ Ｃ Ｌ ＳＯ ＳＭＡＬＬ ＯＵＴＬＩＮＥ ＰＡＣＫＡＧＥ （０ ． １ ５ ０ ｉ ｎ ． ） Ｈ Ｂ ｅ ＭＩＬＬＩＭＥＴＥＲＳ ＭＩＮ ０．０５０ １．２７ Ｈ ０．２２８ ０．２４４ ５．８０ ６．２０ Ｌ ０．０１６ ０．０５０ ０．４０ １．２７ ＤＩＭ ＰＩＮＳ Ｄ ＩＮＣＨＥＳ ＭＩＬＬＩＭＥＴＥＲＳ ＭＩＮ ＭＡＸ ＭＩＮ ＭＡＸ ８ ０．１８９ ０．１９７ ４．８０ ５．００ Ｄ １４ ０．３３７ ０．３４４ ８．５５ ８．７５ Ｄ １６ ０．３８６ ０．３９４ ９．８０ １０．００ ２１－００４１Ａ Ｅ Ｅ１ Ｄ Ａ３ Ａ Ｌ Ａ２ ｅ Ｂ ＳＴＣ３４８５Ｅ Ｄａｔａｓｈｅｅｔ Ｒｅｖ．０．１， Ｄｅｃ．２００５ ＭＡＸ － ０．２００ － ５．０８ － ０．３８ － ０．１２５ ０．１７５ ３．１８ ４．４５ Ａ３ ０．０５５ ０．０８０ １．４０ ２．０３ Ｂ ０．０１６ ０．０２２ ０．４１ ０．５６ Ｂ１ ０．０４５ ０．０６５ １．１４ １．６５ Ｃ ０．００８ ０．０１２ ０．２０ ０．３０ Ｄ１ ０．００５ ０．０８０ ０．１３ ２．０３ Ｅ ０．３００ ０．３２５ ７．６２ ８．２６ Ｅ１ ０．２４０ ０．３１０ ６．１０ ７．８７ ｅ ０．１００ － ２．５４ － ｅＡ ０．３００ － ７．６２ － ｅＢ － ０．４００ － １０．１６ Ｌ ０．１１５ ０．１５０ ２．９２ ３．８１ Ｄ１ Ｐｌａｓｔｉｃ ＤＩＰ ＰＬＡＳＴＩＣ ＤＵＡＬ－ＩＮ－ＬＩＮＥ ＰＡＣＫＡＧＥ （０．３００ｉｎ．） ＭＩＮ Ａ ０．０１５ ｅＡ ｅＢ ＭＡＸ Ａ１ Ｃ Ｂ１ ＭＩＬＬＩＭＥＴＥＲＳ ＭＩＮ Ａ２ ０°－ １５° Ａ１ ＩＮＣＨＥＳ ＤＩＭ ＩＮＣＨＥＳ ＭＩＬＬＩＭＥＴＥＲＳ ＤＩＭ ＰＩＮ ＭＩＮ ＭＡＸ ＭＩＮ ＭＡＸ Ｄ ８ ０．３４８ ０．３９０ ８．８４ ９．９１ Ｄ １４ ０．７３５ ０．７６５ １８．６７ １９．４３ Ｄ １６ ０．７４５ ０．７６５ １８．９２ １９．４３ Ｄ １８ ０．８８５ ０．９１５ ２２．４８ ２３．２４ Ｄ ２０ １．０１５ １．０４５ ２５．７８ ２６．５４ Ｄ ２４ １．１４ １．２６５ ２８．９６ ３２．１３ Ｐａｇｅ ｏｆ １１ １１