DS36C279 Low Power EIA-RS-485 Transceiver with Sleep Mode General Description Features The DS36C279 is a low power differential bus/line transceiver designed to meet the requirements of RS-485 Standard for multipoint data transmission. In addition it is compatible with TIA/EIA-422-B. The sleep mode feature automatically puts the device in a power saving mode when both the driver and receiver are disabled.†† The device is ideal for use in power conscious applications where the device may be disabled for extended periods of time. The driver and receiver outputs feature TRI-STATE ® capability. The driver outputs operate over the entire common mode range of −7V to +12V. Bus contention or fault situations that cause excessive power dissipation within the device are handled by a thermal shutdown circuit, which forces the driver outputs into a high impedance state. The receiver incorporates a fail safe circuit which guarantees a high output state when the inputs are left open.† The DS36C279T is fully specified over the industrial temperature range (−40˚C to +85˚C). n 100% RS-485 compliant — Guaranteed RS-485 device interoperation n Low power CMOS design: ICC 500 µA max n Automatic sensing sleep mode — Reduces ICC to 10 µA maximum n Built-in power up/down glitch-free circuitry — Permits live transceiver intersection/displacement n DIP and SOIC packages available n Industrial temperature range: −40˚C to +85˚C n On-board thermal shutdown circuitry — Prevents damage to the device in the event of excessive power dissipation n Wide common mode range: −7V to +12V n Receive open input fail-safe (Note 1) n 1⁄4 unit load (DS36C279): ≥ 128 nodes n 1⁄2 unit load (DS36C279T): ≥ 64 nodes n ESD (Human Body Model): ≥ 2 kV n Drop-in replacement for: — LTC485 MAX485 DS75176 DS3695 Connection and Logic Diagram Truth Table DRIVER SECTION RE* DE DI DO/RI X H H H DO*/RI* L X H L L H X L X Z Z RECEIVER SECTION DS012053-1 Order Number DS36C279M, DS36C279N, DS36C279TM or DS36C279TN 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 (Note 2) L L OPEN (Note 1) H Note 1: Non-terminated, open input only Note 2: Device enters sleep mode if enable conditions are held 600 ns TRI-STATE ® is a registered trademark of National Semiconductor Corporation. © 1999 National Semiconductor Corporation DS012053 www.national.com DS36C279 Low Power EIA-RS-485 Transceiver with Sleep Mode July 1998 Absolute Maximum Ratings (Note 3) Storage Temperature Range Lead Temperature (Soldering 4 sec) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. −65˚C to +150˚C +260˚C Recommended Operating Conditions Supply Voltage (VCC) +12V Input Voltage (DE, RE*, & DI) −0.5V to (VCC +0.5V) Common Mode (VCM) ± 15V Driver Output/Receiver Input ± 14V Input Voltage (DO/RI, DO*/RI*) Receiver Output Voltage −0.5V to (VCC +0.5V) Maximum Package Power Dissipation @ +25˚C M Package 1190 mW, derate 9.5 mW/˚C above +25˚C N Package 744 mW, derate 6.0 mW/˚C above +25˚C Supply Voltage (VCC) Min Typ Max Units +4.75 +5.0 +5.25 V +12 V Bus Voltage −7 Operating Free Air Temperature (TA) DS36C279T −40 +25 +85 ˚C 0 +25 +70 ˚C DS36C279 Electrical Characteristics (Notes 4, 5) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Reference Min Typ Max Units (422) (485) 1.5 5.0 0 5.0 V 0 5.0 V DIFFERENTIAL DRIVER CHARACTERISTICS VOD1 Differential Output Voltage IO = 0 mA (No Load) VOD0 Output Voltage IO = 0 mA VOD0* Output Voltage (Output to GND) VOD2 ∆VOD2 Differential Output Voltage RL = 50Ω (422) (Termination Load) RL = 27Ω (485) Balance of VOD2 RL = 27Ω or 50Ω (Note 6) |VOD2 − VOD2*| VOD3 VOC ∆VOC IOSD Figure 1 V 2.0 2.8 1.5 2.3 5.0 V V −0.2 0.1 +0.2 V 1.5 2.0 5.0 V 0 3.0 V 0 3.0 V −0.2 +0.2 V (422, 485) Differential Output Voltage R1 = 54Ω, R2 = 375Ω (Full Load) VTEST = −7V to +12V Figure 2 Driver Common Mode RL = 27Ω (485) Output Voltage RL = 50Ω (422) Balance of VOC RL = 27Ω or |VOC − VOC*| RL = 50Ω Figure 1 (Note 6) (422, 485) Driver Output Short-Circuit VO = +12V (485) Figure 4 200 +250 mA Current VO = −7V (485) −190 −250 mA +0.035 +0.2 V RECEIVER CHARACTERISTICS VTH VTL Differential Input High Threshold Voltage −7V ≤ VCM ≤ +12V VO = VOH, IO = −0.4 mA Differential Input Low Threshold Voltage −7V ≤ VCM ≤ +12V VO = VOL, IO = 0.4 mA VHST Hysteresis VCM = 0V RIN Input Resistance −7V ≤ VCM ≤ +12V IIN (Note 7) (422, 485) Line Input Current Other Input = 0V, (Note 9) DE = VIL, RE* = VIL, −0.2 −0.035 V 70 mV DS36C279T 24 68 kΩ DS36C279 48 68 kΩ (Note 8) DS36C279 VCC = 4.75 to 5.25 DS36C279T or 0V IING Line Input Current Glitch (Note 9) Other Input = 0V, DE = VIL, RE* = VIL, DS36C279 VCC = +3.0V or 0V, TA = 25˚C DS36C279T IB Input Balance Test RS = 500Ω VOH High Level Output Voltage IOH = −4 mA, VID = +0.2V VOL Low Level Output Voltage IOL = +4 mA, VID = −0.2V www.national.com VIN = +12V 0 0.19 0.25 mA VIN = −7V 0 −0.1 −0.2 mA VIN = +12V 0 0.19 0.5 mA VIN = −7V 0 −0.1 −0.4 mA VIN = +12V 0 0.19 0.25 mA VIN = −7V 0 −0.1 −0.2 mA VIN = +12V 0 0.19 0.5 mA VIN = −7V 0 −0.1 −0.4 mA ± 400 mV 3.5 4.6 (422) (Note 12) 2 RO Figure 11 0.3 V 0.5 V Electrical Characteristics (Notes 4, 5) (Continued) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Reference Min Typ RO 7 35 Max Units RECEIVER CHARACTERISTICS IOSR Short Circuit Current VO = GND IOZR TRI-STATE Leakage Current VO = 0.4V to 2.4V 85 mA ±1 µA 2.0 VCC V GND 0.8 V 2 µA −2 µA DEVICE CHARACTERISTICS VIH High Level Input Voltage VIL Low Level Input Voltage IIH High Level Input Current VIH = VCC IIL Low Level Input Current VCC = 5V DE, RE*, DI VIL = 0V VCC = +3.0V ICC ICCR Power Supply Current (No Load) Driver and Receiver ON Driver OFF, Receiver ON ICCD Driver ON, Receiver OFF ICCX Sleep Mode VCC −2 µA 200 500 µA 200 500 µA 200 500 µA 0.2 10 µA Switching Characteristics (Notes 5, 10) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Reference Min Typ Max Units 10 39 80 ns 10 40 80 ns 0 1 10 ns ns DRIVER CHARACTERISTICS tPHLD Differential Propagation Delay High to Low tPLHD Differential Propagation Delay Low to High tSKD Differential Skew RL = 54Ω, CL = 100 pF Figures 5, 6 |tPHLD − tPLHD| tr Rise Time 3 25 50 tf Fall Time 3 25 50 ns tPHZ Disable Time High to Z Figures 7, 8 80 200 ns tPLZ Disable Time Low to Z Figures 9, 10 tPZH Enable Time Z to High tPZL tPSH tPSL CL = 15 pF RE* = L 80 200 ns Figures 7, 8 50 200 ns Enable Time Z to Low CL = 100 pF RE* = L Figures 9, 10 65 200 ns Driver Enable from Sleep CL = 100 pF Figures 7, 8 70 98 250 ns Mode to Output High (Note 11) Figures 9, 10 70 98 250 ns Figures 12, 13 30 210 400 ns 30 190 400 ns Driver Enble from Sleep CL = 100 pF Mode to Output Low (Note 11) RECEIVER CHARACTERISTICS tPHL Propagation Delay CL = 15 pF High to Low tPLH Propagation Delay Low to High tSK Skew, |tPHL − tPLH| tPLZ Output Disable Time tPHZ tPZL 0 CL = 15 pF DE = H Figures 14, 15, 16 Output Enable Time tPZH tPSH tPSL Receiver Enable from Sleep CL = 15 pF Mode to Output High (Note 11) Receiver Enable from Sleep CL = 15 pF 3 20 50 ns 50 150 ns 55 150 ns 40 150 ns 45 150 ns Figures 14, 16 70 97 250 ns Figures 14, 15 70 95 250 ns www.national.com Switching Characteristics (Notes 5, 10) (Continued) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Reference Min Typ Max Units RECEIVER CHARACTERISTICS Mode to Output Low (Note 11) Note 3: “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 4: 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 and VOD2. Note 5: All typicals are given for: VCC = +5.0V, TA = + 25˚C. Note 6: Delta |VOD2| and Delta |V OC| are changes in magnitude of VOD2 and VOC , respectively, that occur when input changes state. Note 7: Threshold parameter limits specified as an algebraic value rather than by magnitude. Note 8: Hysteresis defined as VHST = VTH − VTL. Note 9: IIN includes the receiver input current and driver TRI-STATE leakage current. Note 10: CL includes probe and jig capacitance. Note 11: For enable from sleep mode delays DE = L and RE* = H for greater than 600 ns prior to test (device is in sleep mode). Note 12: For complete details of test, see RS-485. Parameter Measurement Information DS012053-3 FIGURE 3. Driver VOH and VOL DS012053-2 FIGURE 1. Driver VOD2 and VOC DS012053-4 Vtest = −7V to +12V FIGURE 4. Driver IOSD DS012053-17 FIGURE 2. Driver VOD3 DS012053-5 FIGURE 5. Driver Differential Propagation Delay Test Circuit www.national.com 4 Parameter Measurement Information (Continued) DS012053-6 FIGURE 6. Driver Differential Propagation Delays and Differential Rise and Fall Times DS012053-10 FIGURE 10. TRI-STATE and Sleep Mode Waveforms (tPZL, (tPSL), tPLZ) DS012053-7 FIGURE 7. TRI-STATE and Sleep Mode Test Circuit (tPZH, (tPSH), tPHZ) DS012053-11 DS012053-8 FIGURE 11. Receiver VOH and VOL FIGURE 8. TRI-STATE and Sleep Mode Waveforms (tPZH, (tPSH), tPHZ) DS012053-12 FIGURE 12. Receiver Differential Propagation Delay Test Circuit DS012053-9 FIGURE 9. TRI-STATE and Sleep Mode Test Circuit (tPZL, (tPSL), tPLZ) 5 www.national.com Parameter Measurement Information (Continued) DS012053-13 FIGURE 13. Receiver Differential Propagation Delay Waveforms DS012053-14 FIGURE 14. Receiver TRI-STATE and Sleep Mode Test Circuit DS012053-15 FIGURE 15. Receiver Enable and Disable Waveforms (tPLZ, tPZL, (tPSL)) DS012053-16 FIGURE 16. Receiver Enable and Disable Waveforms (tPHZ, tPZH, (tPSH)) www.national.com 6 Parameter Measurement Information (Continued) DS012053-19 FIGURE 17. Entering Sleep Mode Conditions Typical Application Information DS012053-18 FIGURE 18. Typical RS-485 Bus Interface 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). When RE* is HIGH and DE is LOW, the device will enter a low-current sleep mode after 600 ns. 3 DE Driver Output Enable: When DE is HIGH, the driver outputs are enabled. When DE is LOW, the driver outputs are in TRI-STATE (OFF). When RE* is HIGH and DE is LOW, the device will enter a low-current sleep mode after 600 ns. 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 Driver Output/Receiver Input, 485 Bus Pin. 7 DO*/RI* Driver Output/Receiver Input, 485 Bus Pin. 8 VCC Positive Power Supply Connection: Recommended operating range for VCC is +4.75V to +5.25V. Unit Load unit load (see Figure 19). 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 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 7 www.national.com Unit Load (Continued) 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 DS36C278, the DS36C279, and the DS36C280 all have 1⁄2 unit load and 1⁄4 unit load (UL) options available. These devices 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. First, for a 1⁄2 UL device the top and bottom borders shown in Figure 19 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 19). Second, for a 1⁄4 UL device the top and bottom borders shown in Figure 19 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 19). 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 DS36C278/279/280 may save in the cost of extra devices like repeaters, extra media like cable, and/or extra components like resistors. www.national.com DS012053-20 FIGURE 19. Input Current vs Input Voltage Operating Range The DS36C279 and DS36C280 have an additional feature which offers more advantages. The DS36C279 has an automatic sleep mode function for power conscious applications. The DS36C280 has a slew rate control for EMI conscious applications. Refer to the sleep mode and slew rate control portion of the application information section in the corresponding datasheet for more information on these features. Sleep Mode The DS36C279 features an automatic shutdown mode that allows the device to save power when not transmitting data. Since the shutdown mode is automatic, no external components are required. It may be used as little or as much as the application requires. The more the feature is utilized, the more power it saves. The sleep mode is automatically entered when both the driver and receiver are disabled. This occurs when both the DE pin is asserted to a logic low and the RE* pin is asserted to a logic high. Once both pins are asserted the device will enter sleep mode typically in 50 ns. The DS36C279 is guaranteed to go into sleep mode within 600 ns after both pins are asserted. The device wakes up (comes out of sleep mode) when either the DE pin is asserted to a logic high and/or the RE* pin is asserted to a logic low. After the device enters sleep mode it will take longer for the device to wake up than it does for the device to enable from TRI-STATE. Refer to datasheet specifications tPSL and tPSH and compare with tPZL and tPZH for timing differences. The benefit of the DS36C279 is definitely its power savings. When active the device has a maximum ICC of 500 µA. When in sleep mode the device has a maximum ICC of only 10 µA, which is 50 times less power than when active. The ICC when the device is active is already very low but when in sleep mode the ICC is ultra low. 8 Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC Order Number DS36C279M or DS36C279TM NS Package Number M08A 8-Lead (0.300" Wide) Molded Dual-In-Line Package Order Number DS36C279N or DS36C279TN NS Package Number N08E 9 www.national.com DS36C279 Low Power EIA-RS-485 Transceiver with Sleep Mode 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. 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