DS36C280 Slew Rate Controlled CMOS EIA-RS-485 Transceiver General Description Features The DS36C280 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 slew rate control feature allows the user to set the driver rise and fall times by using an external resistor. Controlled edge rates can reduce switching EMI. The CMOS design offers significant power savings over its bipolar and ALS counterparts without sacrificing ruggedness against ESD damage. The device is ideal for use in battery powered or power conscious applications. ICC is specified at 500 µA maximum. 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 are handled by a thermal shutdown circuit, which forces the driver outputs into the high impedance state. The receiver incorporates a fail safe circuit which guarantees a high output state when the inputs are left open (Note 1) . n 100% RS-485 compliant — Guaranteed RS-485 device interoperation n Low power CMOS design: ICC 500 µA max n Adjustable slew rate control — Minimizes EMI affects n Built-in power up/down glitch-free circuitry — Permits live transceiver insertion/displacement n SOIC packages 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 Receiver open input fail-safe (Note 1) n 1⁄4 unit load (DS36C280): ≥128 nodes n 1⁄2 unit load (DS36C280T): ≥64 nodes n ESD (human body model): ≥2 kV Connection and Logic Diagram Truth Table DRIVER SECTION DE/RE* DI DO/RI H H H DO*/RI* L H L L H L X Z Z RECEIVER SECTION 01205201 Order Number DS36C280M, DS36C280TM See NS Package Number M08A DE/RE* RI-RI* RO L ≥+0.2V H L ≤−0.2V L H X Z L OPEN (Note 1) H Note 1: Non-terminated, Open Inputs only TRI-STATE ® is a registered trademark of National Semiconductor Corporation. © 2004 National Semiconductor Corporation DS012052 www.national.com DS36C280 Slew Rate Controlled CMOS EIA-RS-485 Transceiver July 2000 DS36C280 Absolute Maximum Ratings (Note 2) Storage Temperature Range If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Lead Temperature Supply Voltage (VCC) Recommended Operating Conditions −0.5V to (VCC +0.5V) Common Mode (VCM) Driver Output/Receiver Input ± 15V Supply Voltage (VCC) Min Typ Max Units +4.75 +5.0 +5.25 V +12 V Bus Voltage Input Voltage (DO/RI, DO*/RI*) ± 14V Receiver Output Voltage −7 Operating Free Air Temperature (TA) −0.5V to (VCC +0.5V) DS36C280T Maximum Package Power Dissipation @ +25˚C M Package 1190 mV, derate +260˚C (Soldering 4 sec.) +12V Input Voltage (DE/RE*, & DI) −65˚C to +150˚C DS36C280 −40 +25 +85 ˚C 0 +25 +70 ˚C 9.5 mW/˚C above +25˚C Electrical Characteristics (Notes 3, 4) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Reference Min Typ Max Units 1.5 5.0 V 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 Differential Output Voltage (Termination Load) RL = 50Ω (422) RL = 27Ω (485) Balance of VOD2 RL = 27Ω or 50Ω ∆VOD2 (422) (485) (Note 5) |VOD2 − VOD2*| VOD3 VOC ∆VOC IOSD Figure 1 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 (422, 485) Differential Output Voltage (Full Load) R1 = 54Ω, R2 = 375Ω VTEST = −7V to +12V Figure 2 Driver Common Mode Output Voltage RL = 27Ω (485) RL = 50Ω (422) Figure 1 (Note 5) 0 3.0 V 0 3.0 V −0.2 +0.2 V Balance of VOC RL = 27Ω or |VOC − VOC*| RL = 50Ω Driver Output Short-Circuit Current VO = +12V (485) Figure 4 200 +250 mA VO = −7V (485) −190 −250 mA +0.035 +0.2 V (422, 485) 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 (Note 6) (422, 485) −0.2 −0.035 V VHST Hysteresis VCM = 0V 70 mV RIN Input Resistance −7V ≤ VCM ≤ +12V DS36C280T 24 68 kΩ RIN Input Resistance −7V ≤ VCM ≤ +12V DS36C280 48 68 kΩ IIN Line Input Current (Note 8) DE = VIL, RE* = VIL Other Input = 0V VCC = 4.75 to 5.25 DS36C280 VIN = +12V 0 0.19 0.25 mA VIN = −7V 0 −0.1 −0.2 mA DS36C280T VIN = +12V 0 0.19 0.5 mA VIN = −7V 0 −0.1 −0.4 mA DS36C280 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 or 0V IING Line Input Current Glitch (Note 8) Other Input = 0V DE = VIL, RE* = VIL VCC = +3.0V DS36C280T or 0V TA = 25˚C IB Input Balance Test www.national.com RS = 500Ω (422) (Note 10) 2 −0.4 mA ± 400 mV (Continued) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Reference Min RO Figure 11 3.5 RO 7 Typ Max Units 0.5 V 85 mA ±1 µA RECEIVER CHARACTERISTICS VOH High Level Output Voltage IOH = −4 mA, VID = +0.2V VOL Low Level Output Voltage IOL = +4 mA, VID = −0.2V IOSR Short Circuit Current VO = GND IOZR TRI-STATE Leakage Current VO = 0.4V to 2.4V 4.6 V 0.3 35 DEVICE CHARACTERISTICS VIH High Level Input Voltage 2.0 VCC V VIL Low Level Input Voltage GND 0.8 V IIH High Level Input Current VIH = VCC 2 µA IIL Low Level Input Current VCC = 5.0V −2 µA DE/RE*, DI VIL = 0V VCC = +3.0V SR = 0V ICCR ICCD Power Supply Current (No Load) −2 µA −1 mA 200 500 µA 200 500 µA SR Driver OFF, Receiver ON VCC Driver ON, Receiver OFF Switching Characteristics (Notes 4, 9, 11) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Reference Min Typ Max Units Figures 5, 6 10 399 1000 ns DRIVER CHARACTERISTICS tPHLD Differential Propagation Delay High to Low tPLHD Differential Propagation Delay Low to High 10 400 1000 ns tSKD Differential Skew 0 1 10 ns RL = 54Ω, CL = 100 pF |tPHLD − tPLHD| tr Rise Time tf Fall Time tr Rise Time tf Fall Time tr Rise Time tf Fall Time tPHZ Disable Time High to Z tPLZ Disable Time Low to Z tPZH Enable Time Z to High tPZL Enable Time Z to Low SR = Open SR = 100 kΩ 2870 ns 3070 ns 1590 ns 1640 SR = Short 100 100 CL = 15 pF CL = 100 pF ns 337 1000 ns ns 348 1000 Figures 7, 8 1100 2000 ns Figures 9, 10 500 800 ns Figures 7, 8 300 500 ns Figures 9, 10 300 500 ns 30 210 400 ns 30 190 400 ns 0 20 50 ns RECEIVER CHARACTERISTICS tPHL Propagation Delay High to Low tPLH Propagation Delay Low to High tSK Skew, |tPHL − tPLH| tPLZ Output Disable Time CL = 15 pF Figures 12, 13 CL = 15 pF tPHZ tPZL Figures 14, 15, 16 Output Enable Time tPZH 50 150 ns 55 150 ns 40 150 ns 45 150 ns 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. 3 www.national.com DS36C280 Electrical Characteristics (Notes 3, 4) DS36C280 Switching Characteristics (Notes 4, 9, 11) (Continued) 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 and VOD2. Note 4: All typicals are given for: VCC = +5.0V, TA = + 25˚C. Note 5: Delta |VOD2| and Delta |VOC| are changes in magnitude of VOD2 and VOC, respectively, that occur when input changes state. Note 6: Threshold parameter limits specified as an algebraic value rather than by magnitude. Note 7: Hysteresis defined as VHST = VTH − VTL. Note 8: IIN includes the receiver input current and driver TRI-STATE leakage current. Note 9: CL includes probe and jig capacitance. Note 10: For complete details of test, see RS-485. Note 11: SR = GND for all Switching Characteristics unless otherwise specified. Parameter Measurement Information 01205202 FIGURE 1. Driver VOD2 and VOC 01205205 FIGURE 5. Driver Differential Propagation Delay Test Circuit 01205218 FIGURE 2. Driver VOD3 01205203 FIGURE 3. Driver VOH and VOL 01205206 FIGURE 6. Driver Differential Propagation Delays and Differential Rise and Fall Times 01205204 Vtest = −7V to +12V FIGURE 4. Driver IOSD www.national.com 4 DS36C280 Parameter Measurement Information (Continued) 01205210 FIGURE 10. TRI-STATE Waveforms (tPZL, tPLZ) 01205207 FIGURE 7. TRI-STATE Test Circuit (tPZH , tPHZ) 01205211 FIGURE 11. Receiver VOH and VOL 01205208 FIGURE 8. TRI-STATE Waveforms (tPZH, tPHZ) 01205212 FIGURE 12. Receiver Differential Propagation Delay Test Circuit 01205209 FIGURE 9. TRI-STATE Test Circuit (tPZL, tPLZ) 01205213 FIGURE 13. Receiver Differential Propagation Delay Waveforms 5 www.national.com DS36C280 Parameter Measurement Information (Continued) 01205214 FIGURE 14. Receiver TRI-STATE Test Circuit 01205215 FIGURE 15. Receiver Enable and Disable Waveforms (tPLZ, tPZL) 01205216 FIGURE 16. Receiver Enable and Disable Waveforms (tPHZ, tPZH) www.national.com 6 DS36C280 Typical Application Information 01205217 FIGURE 17. Typical Pin Connection TABLE 1. Device Pin Descriptions Pin # Name Description Receiver Output: When DE/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. 1 RO 2 SR Slew Rate Control: A resistor connected to Ground controls the Driver Output rising and falling edge rates. 3 DE/RE* Combined Driver and Receiver Output Enable: When signal is LOW the receiver output is enabled and the driver outputs are in TRI-STATE (OFF). When signaI is HlGH, the receiver output is in TRI-STATE (OFF) and the driver outputs are enabled. 4 DI Driver Input: When DE/RE* is HlGH, 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. −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 18 ). Second, for a 1⁄4 UL device the top and bottom borders shown in Figure 18 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 18 ). 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 were 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. The DS36C279 and DS36C280 have addition feature which offer 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. Unit Load A unit load for a 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 18 ). A RS-485 driver is capable of driving up to 32 unit loads. This allows upto 32 nodes on a single bus. Although sufficient for many applications, it is sometime desirable to have even more nodes. For example an aircraft that has 32 rows with 4 seats per row could 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 DS36C278, the DS36C279, and the DS36C280 all have 1⁄2 unit load and 1⁄4 unit load (UL) options available. These devices will allow upto 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 18 are scaled. Both 0 mA reference points at +5V and 7 www.national.com DS36C280 Unit Load tion fixed edge rate devices. The slew rate control may be adjusted with or without any external components. The DS36C280 offers both low power (ICC 500 µA max) and low EMI for an RS-485 interface. (Continued) The slew rate control is located at pin two of the device and only controls the driver output edges. The slew rate control pin (SR) may be left open or shorted to ground, with or without a resistor. When the SR pin is shorted to ground without a resistor, the driver output edges will transition typically 350 ns. When the SR pin is left open, the driver output edges will transition typically 3 µs. When the SR pin is shorted to ground with a resistor, the driver output edges will transition between 350 ns and 3 µs depending on the resistor value. Refer to the slew rate versus resistor value curve in this datasheet for determining resistor values and expected typical slew rate value. Please note, when slowing the edge rates of the device (see Figure 19 ) will decrease the maximum data rate also. 01205219 FIGURE 18. Input Current vs Input Voltage Operating Range Slew Rate Control The DS36C280 features an adjustable slew rate control. This feature allows more control over EMl levels than tradiDifferential Rise/Fall Time vs Slew Rate Resistor 01205220 FIGURE 19. Slew Rate Resistor vs Rise/Fall Time www.national.com 8 DS36C280 Slew Rate Controlled CMOS EIA-RS-485 Transceiver Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead (0.150" Wide) Molded Small Outline Package, JEDEC Order Number DS36C280M or DS36C280TM NS Package Number M08A 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. For the most current product information visit us at www.national.com. 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 AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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