DS1485 High-Speed RS-485/RS-422 Multipoint Transceiver General Description Features The DS1485 is a high-speed low power transceiver for RS485 and RS-422 communication. The device contains one driver and one receiver. The driver’s output transition time supports operation up to 40 Mbps while minimizing power consumption. The transceiver draws 5mA of supply current when unloaded or fully loaded with the driver disabled and operates from a single +5V supply. n n n n n n n The driver is short-circuited current limited and is protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into TRI-STATE ® (High Impedance state) under faut conditions. The driver guarantees a minimum of 1.5V differential output voltage with maximum loading across the common mode range (VOD3). The receiver incorporates a fail safe circuit which guarantees a logic high output state when the inputs are left open. (Note 1) The DS1485 is available in surface mount and DIP packages and is characterized for Industrial (−40˚C to +85˚C) and Commercial temperature range operation. n n n n Connection and Logic Diagram Truth Table n n n Meets TIA/EIA RS-485 Multipoint Standard Supports 40 Mbps operation Guaranteed Full Load Output Voltage (V OD3) Low Quiesent Current 5mA typ −7V to +12V Common−Mode Input Voltage Range TRI-STATE Outputs on Driver and Receiver AC Performance: − Driver Transition Time 3ns typ − Driver Propagation Delay 7ns typ − Driver Skew 0.2ns typ − Receiver Propagation Delay 3ns typ − Receiver Skew 0.3ns typ Half−Duplex Flow Through Pinout Operates from a single 5V supply Allows up to 32 Transceivers on the Bus Current−Limiting and Thermal Shutdown for Driver Overload Protection Industrial temperature range: −40˚C to +85˚C ± 10kV ESD (human body model) Protection on Bus Pins Pin and Functional Compatibility with ADM1485, MAX485, LTC1485, SN75LBC176 and SN75ALS176B DRIVER SECTION DO*/RI* RE* DE DI DO/RI X H H H L X H L L H X L X Z Z RECEIVER SECTION DS100079-1 Order Number DS1485TM, DS1485TN, DS1485M, DS1485N See NS Package Number M08A or N08E RE* DE RI−RI* RO L L ≥ +0.2V H L L ≤ −0.2V L H L X Z L L OPEN (Note 1) H Note 1: Non-terminated, open input only TRI-STATE ® is a registered trademark of National Semiconductor Corporation. © 1999 National Semiconductor Corporation DS100079 Powered by ICminer.com Electronic-Library Service CopyRight 2003 www.national.com DS1485 High-Speed RS-485/RS-422 Multipoint Transceiver September 1997 Absolute Maximum Ratings (Note 2) Lead Temperature (Soldering 4 sec) ESD (HBM) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. +260˚C ≥ 10kV Recommended Operating Conditions Supply Voltage (VCC) −0.5V to +7V Input Voltage (DE, RE*, & DI) −0.5V to (VCC +0.5V) Common Mode (VCM) Driver Output/Receiver Input −10V to +15V Input Voltage (DO/RI, DO*/RI*) −10V to +15V Receiver Output Voltage (RO) −0.5V to (VCC +0.5V) Maximum Package Power Dissipation @ +25˚C M Package TBD mW, derate TBD mW/˚C above +25˚C N Package TBD mW, derate TBD mW/˚C above +25˚C Storage Temperature Range −65˚C to +150˚C Min +4.5 Supply Voltage (VCC) Bus Voltage −7 Operating Free Air Temperature (TA) DS1485 0 DS1485T −40 Typ +5.0 Max +5.5 +12 Units V V 25 25 +70 +85 ˚C ˚C Electrical Characteristics Over Supply Voltage and Operating Temperature ranges, unless otherwise specified ((Note 3) and (Note 4)) Symbol VOD1 Parameter Differential Driver Output Voltage−Unloaded Conditions IO = 0 mA (No Load) Pin Min DO/RI, DO*/RI* 1.5 Typ Differential Driver Output RL = 50Ω (RS−422), Figure 1 2.0 TBD Voltage with load RL = 27Ω (RS−485), Figure 1 1.5 TBD ∆VOD Change in Magnitude of Output Differential Voltage RL = 27Ω or 50Ω, Figure 1 (Note 5) VOD3 Differential Driver Output Voltage (Full Load w/max VCM) R1 = 54Ω, R2 = 375Ω VTEST = −7V to +12V, Figure 2 VOC Driver Common Mode Output Voltage RL = 27Ω or 50Ω, Figure 1 ∆VOC Change in Magnitude of Common Mode Output Voltage RL = 27Ω or 50Ω, Figure 1 (Note 5) VOD2 VIH High Level Input Voltage VIL Low Level Input Voltage IIN1 Input Current VIN = 0V or VCC IIN2 Input Current (Note 6) DE = 0V, VCC = 0V or 5.5V VIN = +12V VTH Receiver Differential Threshold Voltage −7V ≤ VCM ≤ +12V ∆VTH Receiver Input Hysteresis VCM = 0V VOH Receiver Output High Voltage IOH = −4 mA, VID = +0.2V Figure 11 VOL Receiver Output Low Voltage IOL = +4 mA, VID = −0.2V Figure 11 IOZR Receiver TRI-STATE Leakage Current VO = 0.4V to 2.4V RIN Receiver Input Resistance −7V ≤ VCM ≤ +12V ICC Power Supply Current ICCR (No Load) (Note 7) DE = VCC, RE = 0V DE = 0V, RE = 0V DE = VCC, RE = VCC ICCD −0.2 DE, RE*, DI IOSD Driver Output Short-Circuit Current IOSR Receiver Output Short-Circuit Current www.national.com Powered by ICminer.com Electronic-Library Service CopyRight 2003 5.0 V V 5.0 V +0.2 V TBD 5.0 V −1 TBD 3.0 V −0.2 +0.2 V 2.0 VCC V GND 0.8 V ±1 µA −0.2 1.0 mA −0.8 mA +0.2 V 70 RO DO/RI, DO*/RI* VO = +12V (RS−485), Figure 4 VO = −7V (RS−485), Figure 4 0V ≤ VO ≤ VCC V ±1 µA 5 mA kΩ TBD TBD 5 mA TBD 5 mA TBD RO 2 V 0.4 TBD VCC DO/RI, DO*/RI* mV 4.0 DE = 0V, RE = VCC ICCZ Units 1.5 DO/RI, DO*/RI* VIN = −7V Max 5 mA 35 +250 mA −35 −250 mA 7 85 mA Switching Characteristics Over Supply Voltage and Operating Temperature ranges, unless otherwise specified. ((Note 4), (Note 8) and (Note 9)) Symbol Parameter Conditions Min Typ Max Units TBD 10 ns TBD 10 ns 0 TBD 1 ns 0 TBD 2 ns 0 TBD DRIVER CHARACTERISTICS tPHLD Driver Differential Propagation Delay High to Low tPLHD Driver Differential Propagation Delay Low to High tSKEW1 Differential Pulse Skew |tPHLD − t PLHD | @ any specific Differential Channel−Channel Skew (between devices) @ any specific tSKEW2 tSKEW3 Complementary Output Skew (Dynamic Common Mode) RL = 54Ω, CL = 100 pF Figure 5 and Figure 6 over VCC, temp and process VCC/temp VCC/temp (over process) difference in propagation delay between outputs at the 50% point ns tr Driver Rise Time RL = 54Ω, CL = 100 pF 3 TBD 6 ns tf Driver Fall Time Figure 5 and Figure 6 3 TBD 6 ns tPHZ Dr. Disable Time High to Z CL = 15 pF, Figure 7 and Figure 8 20 ns tPLZ Dr. Disable Time Low to Z CL = 15 pF, Figure 9 and Figure 10 20 ns tPZH Dr. Enable Time Z to High CL = 100 pF, Figure 7 and Figure 8 20 ns tPZL Dr. Enable Time Z to Low CL = 100 pF, Figure 9 and Figure 10 20 ns TBD 12 ns TBD 12 ns 0 TBD 1 ns 0 TBD 2 ns RECEIVER CHARACTERISTICS tPHL Receiver Propagation Delay High to Low tPLH Receiver Propagation Delay Low to High tSKEW1 Pulse Skew |tPHL − tPLH| @ any specific Differential Channel−Channel Skew @ any specific tSKEW2 CL = 15 pF Figure 12 and Figure 13 over VCC, temp and process VCC/temp VCC/temp (over process) tPLZ Rec. Disable Time from Low CL = 15 pF TBD 25 ns tPHZ Rec. Disable Time from High Figure 14, Figure 15 and Figure 16 TBD 25 ns tPZL Rec. Enable Time to Low TBD 25 ns tPZH Rec. Enable Time to High TBD 25 fMAX Maximum Data Rate (Note 10) 40 TBD ns Mbps Note 2: “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the devices should be operated at these limits. The table of “Electrical Characteristics” specifies conditions of device operation. Note 3: Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground except VOD1, VOD2, VOD3 and VID. Note 4: All typicals are given for: VCC = +5.0V, TA = + 25˚C. Note 5: Delta |V OD| and Delta |VOC| are changes in magnitude of VOD and VOC, respectively, that occur when input changes state. Note 6: IIN2 includes the receiver input current and driver TRI-STATE leakage current. Note 7: Supply current specification is valid for loaded transmitters when DE = 0V or enabled (DE = H) with no load. Note 8: f = 1MHz, tr and tf ≤ 6ns, Z O = 50Ω. Note 9: CL includes probe and jig capacitance. Note 10: fMAX is the guaranteed data rate for 50 ft of twisted pair cable. fMAX may be conservatively determined from the ratio of driver transition time (tr) to the data rate unit interval (1/f MAX). Using a 25% ratio yields fMAX = 6ns/0.25z40 Mbps. Higher data rates may be supported by allowing larger ratio, or shorter cables. 3 Powered by ICminer.com Electronic-Library Service CopyRight 2003 www.national.com Parameter Measurement Information DS100079-2 FIGURE 1. Driver VOD2 and VOC DS100079-6 FIGURE 6. Driver Differential Propagation Delays and Differential Rise and Fall Times DS100079-18 FIGURE 2. Driver VOD3 DS100079-7 FIGURE 7. TRI-STATE Test Circuit (tPZH , tPHZ) DS100079-3 FIGURE 3. Driver VOH and VOL DS100079-8 FIGURE 8. TRI-STATE Waveforms (tPZH, tPHZ) DS100079-4 Vtest = −7V to +12V FIGURE 4. Driver IOSD DS100079-9 FIGURE 9. TRI-STATE Test Circuit (tPZL, tPLZ) DS100079-5 FIGURE 5. Driver Differential Propagation Delay Test Circuit DS100079-10 FIGURE 10. TRI-STATE Waveforms (tPZL, tPLZ) www.national.com Powered by ICminer.com Electronic-Library Service CopyRight 2003 4 Parameter Measurement Information (Continued) DS100079-12 FIGURE 12. Receiver Differential Propagation Delay Test Circuit DS100079-11 FIGURE 11. Receiver VOH and VOL DS100079-13 FIGURE 13. Receiver Differential Propagation Delay Waveforms DS100079-14 FIGURE 14. Receiver TRI-STATE Test Circuit DS100079-16 DS100079-15 FIGURE 16. Receiver Enable and Disable Waveforms (tPHZ, tPZH) FIGURE 15. Receiver Enable and Disable Waveforms (tPLZ, tPZL) TABLE 1. Device Pin Descriptions Pin No. Name Description 1 RO Receiver Output: When RE (Receiver Enable) is LOW, the receiver is enabled (ON); if DO/RI ≥ DO*/RI* by 200 mV, RO will be HIGH. If DO/RI ≤ DO*/RI* by 200 mV, RO will be LOW. Additionally, RO will be HIGH for open (non-terminated) inputs. 2 RE* Receiver Output Enable: When RE* is LOW, the receiver output is enabled. When RE* is HIGH, the receiver output is in TRI-STATE (OFF). 3 DE Driver Output Enable: When DE is HIGH, the driver outputs (DO/RI and DO*/RI*) are enabled. When DE is LOW, the driver outputs are in TRI-STATE (OFF). Pins DO/RI and DO*/RI* also function as the receiver input pins. 4 DI Driver Input: When DE (Driver Enable) is HIGH, the driver is enabled; if DI is LOW, then DO/RI will be LOW and DO*/RI* will be HIGH. If DI is HIGH, then DO/RI is HIGH and DO*/RI* is LOW. 5 GND Ground Connection. 6 DO/RI Non-inverting Driver Output/Receiver Input pin. Driver ouput levels conform to RS-485 signaling levels. 7 DO*/RI* 8 VCC Inverting Driver Output/Receiver Input pin. Driver ouput levels conform to RS-485 signaling levels. Positive Power Supply Connection: Recommended operating range for V 5 Powered by ICminer.com Electronic-Library Service CopyRight 2003 CC is +4.5V to +5.5V. www.national.com Typical Application Information Unit Load First, for a 1⁄2 UL device the top and bottom borders shown in Figure 17 are scaled. Both 0 mA reference points at +5V and −3V stay the same. The other reference points are +12V at +0.5 mA for the top border and −7V at −0.4 mA for the bottom border (see Figure 17 ). Second, for a 1⁄4 UL device the top and bottom borders shown in Figure 17 are scaled also. Again, both 0 mA reference points at +5V and −3V stay the same. The other reference points are +12V at +0.25 mA for the top border and −7V at −0.2 mA for the bottom border (see Figure 17 ). The advantage of the 1⁄2 UL and 1⁄4 UL devices is the increased number of nodes on one bus. In a single master multi-slave type of application where the number of slaves exceeds 32, the DS1485 may save in the cost of extra devices like repeaters, extra media like cable, and/or extra components like resistors. A unit load for an RS-485 receiver is defined by the input current versus the input voltage curve. The gray shaded region is the defined operating range from −7V to +12V. The top border extending from −3V at 0 mA to +12V at +1 mA is defined as one unit load. Likewise, the bottom border extending from +5V at 0 mA to −7V at −0.8 mA is also defined as one unit load (see Figure 17 ). An RS-485 driver is capable of driving up to 32 unit loads. This allows up to 32 nodes on a single bus. Although sufficient for many applications, it is sometimes desirable to have even more nodes. For example, an aircraft that has 32 rows with 4 seats per row would benefit from having 128 nodes on one bus. This would allow signals to be transferred to and from each individual seat to 1 main station. Usually there is one or two less seats in the last row of the aircraft near the restrooms and food storage area. This frees the node for the main station. The DS1485 has 1⁄2 unit load and 1⁄4 unit load (UL) options available. This device will allow up to 64 nodes or 128 nodes guaranteed over temperature depending upon which option is selected. The 1⁄2 UL option is available in industrial temperature and the 1⁄4 UL is available in commercial temperature. DS100079-19 FIGURE 17. Input Current vs Input Voltage Operating Range www.national.com Powered by ICminer.com Electronic-Library Service CopyRight 2003 6 Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC Order Number DS1485TM, DS1485M NS Package Number M08A 8-Lead (0.300" Wide) Molded Dual-In-Line Package Order Number DS1485TN, DS1485N NS Package Number N08E 7 Powered by ICminer.com Electronic-Library Service CopyRight 2003 www.national.com DS1485 High-Speed RS-485/RS-422 Multipoint Transceiver LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 2. A critical component is any component of a life support 1. Life support devices or systems are devices or sysdevice or system whose failure to perform can be reatems which, (a) are intended for surgical implant into sonably expected to cause the failure of the life support the body, or (b) support or sustain life, and whose faildevice or system, or to affect its safety or effectiveness. ure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 1 80-530 85 85 English Tel: +49 (0) 1 80-532 78 32 Français Tel: +49 (0) 1 80-532 93 58 Italiano Tel: +49 (0) 1 80-534 16 80 National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. Powered by ICminer.com Electronic-Library Service CopyRight 2003