UM3487E ±15kV ESD-Protected, Fail-Safe, Hot-Swappable Auto Polarity Reversal RS-485 Transceivers UM3487E SOP8/DIP8 General Description The UM3487E series are +3.3V powered ±15kV ESD protected, fail-safe, hot-swappable, auto polarity reversal RS-485 transceivers. The device includes fail-safe circuitry, which guarantees a logic-high receiver output when the receiver inputs are open, shorted or idle. This means that the receiver output will be logic high if all transmitters on a terminated bus are disabled (high impedance). The UM3487E features reduced slew-rate driver that minimizes EMI and reduces reflections caused by improperly terminated cables, allowing error-free data transmission up to 500kbps. All transmitter outputs and receiver inputs are protected to ±15kV using the Human Body Model and IEC61000-4-2, Air-Gap Discharge. The UM3487E includes cable auto-invert functions that reverse the polarity of the RS485 bus pins in case the cable is misconnected. Receiver’s full fail-safe features are maintained even when the receiver polarity has been reversed. The transceivers typically draw 300μA of supply current when unloaded, or when fully loaded with the drivers disabled. The device has a 1/8-unit-load receiver input impedance that allows up to 256 transceivers on the bus and is intended for half-duplex communications. Applications Features Smart Meters/Automated Meter Reading Systems Industrial-Control Local Area Networks PROFIBUS® and Other RS-485 Based Field Bus Networks Building Lighting and Environmental Control Systems High Node Count RS-485 Systems Transceivers for EMI-Sensitive Applications Automatic Polarity Reversal RS-485 Transceivers I/O Logic Compatible with +5V, +3.3V & +1.8V Logic ESD Protection for RS-485 I/O Pins ±15kV—IEC61000-4-2, Air-Gap Discharge ±8kV—IEC61000-4-2, Contact Discharge True Fail-Safe Receiver Enhanced Slew-Rate Limiting –7V to +12V Common-Mode Input Voltage Range Allows up to 256 Transceivers on the Bus Thermal Shutdown Current-Limiting for Driver Overload Protection ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 1/15 UM3487E Pin Configurations Top View RO 1 8 VCC RE 2 7 L1 DE 3 6 DI 5 GND 4 UM3487 EESA XX L2 XX: Week Code UM3487EESA SOP8 RO 1 8 VCC RE 2 7 L1 DE 3 6 DI 5 GND 4 UM3487 EEPA XX L2 XX: Week Code UM3487EEPA DIP8 Ordering Information Part Number Marking Code Operating Temperature Package Type UM3487EESA UM3487EESA -40°C to +85°C SOP8 UM3487EEPA UM3487EEPA -40°C to +85°C DIP8 Absolute Maximum Ratings Symbol Parameter Value Unit VCC Supply Voltage +7 V Control Input Voltage (/RE, DE) -0.3V to 7V V Driver Input Voltage (DI) -0.3V to 7V V Driver Output Voltage (L1, L2) -7.5 to +12.5 V Receiver Input Voltage (L1, L2) -7.5 to +12.5 V Receiver Output Voltage (RO) -0.3V to (VCC + 0.3V) V TA Ambient Temperature -40 to +85 °C TSTG Storage Temperature Range -65 to +160 °C TL Lead Temperature for Soldering 10 seconds +300 °C ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 2/15 UM3487E DC Electrical Characteristics (VCC = +3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) Parameter Symbol Test Conditions ICC DE = VCC, No load, /RE=0V or VCC DI = GND DE =0V, or VCC /RE=0V Min Typ Max Unit SUPPLY CURRENT Supply Current Supply Current in Shutdown Mode ISHDN DE = GND, /RE = VCC Input High Voltage VIH1 DE, DI, /RE Input Low Voltage VIL1 DE, DI, /RE DI Input Hysteresis VHYS 0.35 mA 0.25 0.1 1 µA LOGIC 1.5 V 0.4 180 V mV DRIVER Differential Driver Output VOD1 No Load, Figure 2 3.2 Differential Driver Output VOD2 Figure 2, R = 54Ω 1.5 Change-in-Magnitude of Differential Output Voltage ΔVOD Figure 2, R = 54Ω; (Note 2) Driver Common-Mode Output Voltage VOC Figure 2, R = 54Ω Change-in-Magnitude of Common-Mode Voltage ΔVOC Figure 2, R = 54Ω; (Note 2) Driver Short-Circuit Output Current (Note 3) IOSD 3.3 V V 1.4 VOUT = -7V -250 VOUT = 12V 250 0.1 V 1.8 V 0.1 V mA ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 3/15 UM3487E DC Electrical Characteristics (Continued) (VCC = +3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC= +3.3V and TA = +25°C.) (Note 1) Parameter Symbol Test Conditions Min -200 Typ Max Unit -50 mV RECEIVER Receiver Differential Threshold Voltage VTH -7V≤VCM≤12V Receiver Input Hysteresis ΔVTH VCM=0V Receiver Input Resistance RIN -7V≤VCM≤12V Input Current (L1 and L2) IIN2 DE = GND, VCC = GND or 5V 50 mV 96 kΩ VIN = 12V 1.0 VIN = -7V -0.8 mA Receiver Output High Voltage VOH IO = -1.5mA, VID = 200mV VCC -0.2 V Receiver Output Low Voltage VOL IO = 2.5mA, VID = 200mV 0.3 V Three-State Output Current at Receiver IOZR 0V ≤ VO ≤ VCC ±1 µA Receiver Output Short Circuit Current IOSR 0V≤VRO ≤VCC ±40 mA ±10 ESD Protection ESD Protection for A, B Human Body Model IEC61000-4-2 Air Discharge IEC61000-4-2 Contact ±15 ±15 ±8 kV Note 1: All currents into the device are positive; all currents out of the device are negative. All voltages are referred to device ground unless otherwise noted. Note 2: ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes state. Note 3: Maximum current level applies to peak current just prior to fold back current limiting; minimum current level applies during current limiting. ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 4/15 UM3487E Switching Characteristics (VCC = +3.3V ±5%, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) Parameter Symbol Maximum Data Rate fMAX tDPLH Driver Input-to-Output tDPHL Test Conditions Min Typ Max 500 Figures 3 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF Unit kbps 50 100 200 50 100 200 3 100 ns 200 500 ns ns Driver Output Skew | tDPLH - tDPHL | tDSKEW Figures 3 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF Driver Rise or Fall Time tDR, tDF Figures 3 and 7, RDIFF = 54Ω, CL1 = CL2 = 100pF Driver Enable to Output High tDZH Figures 4 and 8, CL = 100pF, S2 closed 100 2500 ns Driver Enable to Output Low tDZL Figures 4 and 8, CL = 100pF, S1 closed 100 2500 ns Driver Disable Time from Low tDLZ Figures 4 and 8, CL = 15pF, S1 closed 50 100 ns Driver Disable Time from High tDHZ Figures 4 and 8, CL = 15pF, S2 closed 50 100 ns Receiver Input to Output tRPLH, tRPHL | VID | ≥1.0V; rise and fall time of VID≤15ns 100 200 ns Differential Receiver Skew | tRPLH - tRPHL | tRSKD Figures 6 and 9; | VID | ≥1.0V; rise and fall time of VID≤15ns 3 30 ns Receiver Enable to Output Low tRZL Figures 5 and 10, CL = 100pF, S1 closed 20 200 ns Receiver Enable to Output High tRZH Figures 5 and 10, CL = 100pF, S2 closed 20 200 ns Receiver Disable Time from Low tRLZ Figures 5 and 10, CL = 100pF, S1 closed 20 200 ns Receiver Disable Time from High tRHZ Figures 5 and 10, CL = 100pF, S2 closed 20 200 ns Time to Shutdown tSHDN (Note 4) 200 600 ns Driver Enable from Shutdown to Output High tDZH(SHDN) Figures 4 and 8, CL = 15pF, S2 closed 4500 ns Driver Enable from Shutdown to Output Low tDZL(SHDN) Figures 4 and 8, CL = 15pF, S1 closed 4500 ns Receiver Enable from Shutdown to Output High tRZH(SHDN) Figures 5 and 10, CL = 100pF, S2 closed 3500 ns Receiver Enable from Shutdown to Output Low tRZL(SHDN) Figures 5 and 10, CL = 100pF, S1 closed 3500 ns 100 50 Note 4: The device is put into shutdown by bringing /RE high and DE low. If the enable inputs are in this state for less than 50ns, the device is guaranteed not to enter shutdown. If the enable inputs are in this state for at least 600ns, the device is guaranteed to have entered shutdown. ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 5/15 UM3487E Non-Polarity Features The Polarities of driver and receiver is always kept the same status. When DE=/RE=LOGIC 0 and RO is standing LOGIC 0 for TS time, the polarities will be reversed automatically. Parameter Symbol Test Conditions Min Typ Max Unit Waiting Time for Inverting Ts DE=/RE=L, RO keeps L 150 200 250 ms Pin Description Pin Number Symbol Function 1 RO 2 /RE 3 DE 4 DI Receiver Output. Receiver Enable. Drive /RE low to enable Receiver, RO is high impedance when /RE is high. Drive /RE high and DE low to enter low-power shutdown mode. Driver Enable. Drive DE high to enable drivers. The outputs are high impedance when DE is low. Drive /RE high and DE low to enter low-power shutdown mode. Driver Input. 5 GND 6 L2 7 L1 8 VCC Ground Auto Polarity Reversal Receiver Input and Driver Output Pin. When power up, the bus pins have their normal polarity definition of L2 as non-inverting and L1 as inverting; otherwise L2 become inverting and L1 become non inverting for reversal status. Power Supply for RS-485 transceiver RS-485 Communication Function Table Table1. Transmitting /RE X X L H INPUTS DE H H L/O L/O OUTPUTS DI H/O L X X A H L Z B L H Z Shutdown Table2. Receiving /RE L L L H H INPUTS DE X X X H L VID=VA-VB ≥-50mV ≤-200mV Open/Shorted X X OUTPUTS RO H L H Z Shutdown H: High, L: Low, X: Do not care, Z: High impedance. In normal RS485 Polarity Status, L2=A and L1=B, otherwise L2=B and L1=A. ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 6/15 UM3487E Typical Operating Characteristics (VCC=3.3V, driver output and receiver output no load, unless otherwise noted.) RLOAD=5kΩ RLOAD=54Ω RLOAD=5kΩ ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 7/15 UM3487E Typical Operating Characteristics (Continued) (VCC=3.3V, driver output and receiver output no load, unless otherwise noted.) RLOAD=54Ω RLOAD=54Ω ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 8/15 UM3487E Typical Operating Circuit 120ohm 120ohm DI L1 B L1 L2 A L2 DE D D DE R L2 L2 L1 500ohm 500ohm L1 RO RE RO RE R Master Node R GND DI Terminal Slave Node R D +5V DI D DE RO RE Slave Node1 DI DE RO RE Slave Node N All UM3487E's L1 L2 pin can interchange each other; Figure 1. Typical Half-Duplex Non-Polarity RS-485 Network Test Circuit L1 3V DE RLOAD/2 VOD CL2 L2 DI VOD2 RDIFF L1 CL1 RLOAD/2 VOC L2 Figure 2. Driver DC Test Load Driver Output Under Test CL 500ohm Figure 3. Driver Timing Test Circuit S1 1K Test Point VCC Receive VCC Output S1 + CRL + 15pF 1K S2 S2 Figure 4. Driver Enable/Disable Timing Test Load Figure 5. Receiver Enable/Disable Timing Test Load ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 9/15 UM3487E B ATE Receiver Output R VD A Figure 6. Receiver Propagation Delay Test Circuit 3V 3V DI 0V tDPLH DE 0V tDPHL L1 1/2VO VO 1.5V 1.5V 1.5V 1.5V 1/2VO tDZL(SHDN), tDZL 1.4V L2 VOL VO 90% VDIFF 0V VDIFF = VL1 - VL2 90% VOH tSKEW=|tDPLH-tDPHL| 10% tDR Output Normally Low VOL+0.5V Output Normally High VOH-0.5V 1.4V 10% -VO tDLZ L1 VOH L2 VOL tDZH(SHDN), tDZH tDF Figure 7. Driver Propagation Delays tDHZ Figure 8. Driver Enable and Disable Times 3V 1.5V 1.5V RE 0V VOH tRZL(SHDN), tRZL tRLZ 1.5V Output Normally Low VOH 1.5V 1.5V RO VOL OUTPUT tRPHL L1 -1V 1.5V tRPLH L2 1V INPUT Figure 9. Receiver Propagation Delays VOL+0.5V RO VOH-0.5V Output Normally High VOL tRZH(SHDN), tRZH tRHZ Figure 10. Receiver Enable and Disable Times ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 10/15 UM3487E Detail Description Polarity Reversal Function With large node count RS485 network, it is common for some cable data lines to be wired backwards during installation. When this happens, the node is unable to communicate over, he must then rewire the connector, which is time consuming. The UM3487E simplifies this task by including an automatic polarity reversal function inside. Upon UM3487E power up, when DE=/RE=logic low, and RO keeps logic low over a predefined time TS (i.e. TS=200ms in UM3487E), the chip reverse its bus pins polarity, so B become non-inverting, and A become inverting. Otherwise, the chip operates like any standard RS485 transceiver, and the bus pins have their normal polarity definition of A as non inverting and B as inverting. Union Semi’s unique automatic polarity reversal function is superior to that found on competing devices, because the receiver’s full fail safe function is maintained, even when the RX polarity is reversed. Fail-Safe and Hot-Swap The UM3487E 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. This is done by setting the receiver input threshold between -50mV and -200mV. If the differential receiver input voltage VID is greater than or equal to -50mV, RO id logic high. If VID 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 threshold of UM3487E, this results in logic high with a 50mV minimum noise margin, and this -50mV to -200mV threshold complies with the ±200mV EIA/TIA-485 standard. When circuit boards with RS485 transceiver are inserted into a hot or powered backplane, differential disturbances to the data bus cab lead to data errors. Upon initial circuit board insertion, the microprocessor undergoes its own power-up sequence. During this period, the processor/s logic output drivers are high impedance and 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 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 facts could improperly enable the transceiver’s driver or receiver. When VCC rises, an internal pull down circuit holds DE low and /RE high. After the initial power up sequence, the pull down/pull up circuit becomes transparent, resetting the hot-swap tolerable input. This hot-swap input circuit enhances UM3487E’s performance in harsh environment application. ±15kV ESD Protection All pins on UM3487E device include ESD protection structures, and the family incorporates advanced structures which allow the RS-485 pins (L1, L2) to survive ESD events up to ±15kV. The RS-485 pins are particularly vulnerable to ESD damage because they typically connect to an exposed port on the exterior of the finished product. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, circuits keep working without latch up. The ESD protection can be tested in various ways and with reference to the ground pin. The L1, L2 are characterized for protection to the following limits: ±15kV using the Human Body Model and IEC61000-4-2, Air-Gap Discharge, and ±8kV Contact Discharge. The logic pins (RO, /RE, DE, DI) are characterized for protection to the following limits: ±2kV using the Human Body Model. ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 11/15 UM3487E Applications Information Non-Polarity transceiver When established the non-polarity RS-485 net, you should pay attention to two conditions. First, a pair of bias resistance (pull-up to +5V for RS-485 A bus, push-down to GND for RS-485 B bus) must be required, usually be built in the master node, or independently, 500Ω resistance is recommended. The other nodes don’t need bias resistance anymore. Second, the transceiver rate must be higher than 100bps or the maximum transmitting time for low logic should be less than 100ms. 256 Transceivers on the Bus The standard RS-485 receiver input impedance is 12kΩ (one unit load), and the standard driver can drive up to 32 unit loads. The Union family of transceivers have a 1/8 unit load receiver input impedance (96kΩ), allowing up to 256 transceivers to be connected in parallel on one communication line. Any combination of these devices and/or other RS-485 transceivers with a total of 32 unit loads or less can be connected to the line. Low-Power Shutdown Mode Low-power shutdown mode is initiated by bringing both /RE high and DE low. In shutdown, the device typically draws only 10uA of supply current. /RE and DE may be driven simultaneously; the parts 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 600ns, the parts are guaranteed to enter shutdown. Enable times tZH and tZL in the Switching Characteristics tables assume the part was not in a low-power shutdown state. Enable times tZH(SHDN) and tZL(SHDN) assume the parts were shut down. It takes drivers and receivers longer to become enabled from low-power shutdown mode (tZH(SHDN), tZL(SHDN)) than from driver/receiver-disable mode (tZH, tZL). Driver Output Protection Two mechanisms prevent excessive output current and power dissipation caused by faults or by bus contention. The first, 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). The second, a thermal shutdown circuit, forces the driver outputs into a high-impedance state if the die temperature becomes excessive. Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. For line lengths greater than 4000 feet, repeater is required. Typical Applications The UM3487E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. 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. ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 12/15 UM3487E Package Information UM3487EESA SOP8 Outline Drawing c E E1 L D 1 2 θ e Top View A A2 End View A1 b Side View DIMENSIONS MILLIMETERS INCHES Symbol Min Max Min Max A 1.350 1.750 0.053 0.069 A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 b 0.33 0.51 0.013 0.020 c 0.170 0.250 0.006 0.010 D 4.700 5.100 0.185 0.200 E 3.800 4.000 0.150 0.157 E1 5.800 6.200 0.228 0.244 e 1.270 (BSC) 0.050 (BSC) L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8° 4.95 1.30 Land Pattern 1.27 0.50 NOTES: 1. Compound dimension: 4.90×3.90 ; 2. Unit: mm; 3. General tolerance ±0.05mm unless otherwise specified; 4. The layout is just for reference. Tape and Reel Orientation UM3487 EESA XX ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 13/15 UM3487E UM3487EEPA DIP8 Outline Drawing D1 E E1 eA C D A1 L A3 A2 A eB b1 e b DIMENSIONS MILLIMETERS INCHES Symbol Min Max Min Max A 5.08 0.200 A1 0.38 0.015 A2 3.18 4.45 0.125 0.175 A3 1.40 2.03 0.055 0.080 b 0.41 0.56 0.016 0.022 b1 1.14 1.65 0.045 0.065 C 0.20 0.30 0.008 0.012 D 8.84 9.91 0.348 0.390 D1 0.13 2.03 0.005 0.080 E 7.62 8.26 0.300 0.325 E1 6.10 7.87 0.240 0.310 e 2.54 0.100 eA 7.62 0.300 eB 10.16 0.400 L 2.92 3.81 0.115 0.150 Tape and Reel Orientation UM3487 EEPA XX ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 14/15 UM3487E IMPORTANT NOTICE The information in this document has been carefully reviewed and is believed to be accurate. Nonetheless, this document is subject to change without notice. Union assumes no responsibility for any inaccuracies that may be contained in this document, and makes no commitment to update or to keep current the contained information, or to notify a person or organization of any update. Union reserves the right to make changes, at any time, in order to improve reliability, function or design and to attempt to supply the best product possible. Union Semiconductor, Inc Add: Unit 606, No.570 Shengxia Road, Shanghai 201210 Tel: 021-51093966 Fax: 021-51026018 Website: www.union-ic.com ________________________________________________________________________ http://www.union-ic.com Rev.03 Dec.2014 15/15