DS16F95A TIA/EIA-485-A (RS-485) Extended Temperature Differential Bus Transceiver General Description The DS16F95A Differential Bus Transceiver is a monolithic integrated circuit designed for bidirectional data communication on balanced multipoint bus transmission lines. The transceiver conforms to both TIA/EIA-485-A and TIA/EIA-422-B standards. The DS16F95A offers improved performance due to the use of L-FAST bipolar technology. The L-FAST technology allows for higher speeds and lower currents by minimizing gate delay times. The DS16F95A features an extended temperature range and is offered in a rugged ceramic package. The DS16F95A combines a TRI-STATE® differential line driver and a differential input line receiver, both of which operate from a single 5.0V power supply. The driver and receiver have an active Enable that can be externally connected to function as a direction control. The driver differential outputs and the receiver differential inputs are internally connected to form differential input/output (I/O) bus ports that are designed to offer minimum loading to the bus whenever the driver is disabled or when VCC = 0V. These ports feature wide positive and negative common mode voltage ranges, making the device suitable for multipoint applications in noisy environments. The driver is designed to accommodate loads of up to 60 mA of sink or source current and features positive and negative current limiting for protection from line fault conditions. The device is offered in a rugged 8–lead Ceramic DIP package and is functional over the extended temperature range of -55 °C to +180 °C. Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Extended temperature range to +180 °C Conforms to TIA/EIA-485-A Designed for multipoint transmission Wide positive and negative I/O bus voltage range Driver positive and negative current-limiting High impedance receiver input Receiver input hysteresis of 50 mV typical Operates from single 5.0V supply Reduced power consumption Pin compatible with DS16F95/DS3695 and SN75176A Available in a 8-lead ceramic DIP package Function Tables Logic Diagram Driver Driver Input Enable Outputs DI DE A H H H L L H L H X L Z Z B Receiver 30066720 Differential Inputs Enable Output A–B RE RO VID ≥ 0.2V L H VID ≤ −0.2V L L 0.2V > VID >-0.2V L X X H Z H = High Level L = Low Level X = Immaterial Z = High Impedance (Off) TRI-STATE® is a registered trademark of National Semiconductor Corporation. © 2008 National Semiconductor Corporation 300667 www.national.com DS16F95A TIA/EIA-485-A (RS-485) Extended Temperature Differential Bus Transceiver November 11, 2008 DS16F95A Recommended Operating Conditions (Note 10) Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the national Semiconductor Sales office/ Distributor for availability and specifications. Storage Temperature Range (Note 10) Lead Temperature (Soldering, 60 sec.) Junction Temperature Maximum Package Power Dissipation Capacity (J) Above 25°C, derate J package Supply Voltage Input Voltage (Bus Terminal) Enable Input Voltage ESD Ratings Min Typ Max Supply Voltage (VCC) 4.50 5.0 5.50 Voltage at Any Bus Terminal (Separately or Common Mode) (VI or VCM) −7.0 +12 Differential Input ±12 Voltage (VID) Output Current HIGH (IOH) Driver −60 Receiver −400 −65°C to +175°C 300°C +200°C 1300 mW 8.7 mW/°C 7.0V +15V/−10V 5.5V (Note 11) Output Current LOW (IOL) Driver Receiver Operating Temperature (TA) -55 60 16 +25 +180 Units V V V mA μA mA mA °C Driver Electrical Characteristics (Notes 2, 3) Over recommended supply voltage and operating temperature ranges, unless otherwise specified. Symbol Parameter Conditions VIH Input Voltage HIGH VIL Input Voltage LOW VIC Input Clamp Voltage II = −18 mA IIH Input Current HIGH VI = 2.4V IIL Input Current Low VI = 0.4V |VOD1| Differential Output Voltage |VOD2| Differential Output Voltage Δ|VOD| VOC DI, DE Typ Max 2.0 A-B, Figure 1 IO = 0 mA, No Load 3.6 RL = 100Ω 2.0 2.9 RL = 54Ω 1.5 2.6 RL = 54Ω or 100Ω, (Note 4) (A+B)/2, Figure 1 2.5 V 20 μA -50 μA 6.0 V V ±0.4 V 3.0 V ±0.2 V Change in Magnitude of Common Mode Output Voltage (Note 4) IO Output Current (Note 8) (Includes Receiver II) A or B, Output Disabled, DE = 0.4V VO = +12V 0.57 1.5 VO = −7.0V -0.43 -0.8 Short Circuit Output Current (Note 9) A or B VO = −7.0V -157 -250 VO = 0V -115 -150 VO = VCC 112 150 VO = +12V 137 250 www.national.com 2 V -1.3 Δ|VOC| IOS Units V 0.8 Change in Magnitude of Differential Output Voltage Common Mode Output Voltage (Note 5) Min mA mA (Note 2) Over recommended supply voltage and operating temperature ranges, unless otherwise specified. Symbol Parameter Min Typ Max Units 8.0 15 45 ns 8.0 15 30 ns RL = 110Ω, Figure 4 25 50 ns Output Enable Time to Low Level RL = 110Ω, Figure 5 25 50 ns tHZ Output Disable Time from High Level RL = 110Ω, Figure 4 20 80 ns tLZ Output Disable Time from Low Level RL = 110Ω, Figure 5 20 80 ns tLZL Output Disable Time from Low Level with Load Load per Figure 4, Resistor to GND Timing per Figure 5 300 tSKEW Skew (Pulse Width Distortion) tDD Differential Output Delay Time tTD Differential Output Transition Time tZH Output Enable Time to High Level tZL Conditions RL = 60Ω, Figure 3 RL = 60Ω, Figure 3 ns 1.0 12 ns Receiver Electrical Characteristics (Notes 2, 3) Over recommended supply voltage and operating temperature ranges, unless otherwise specified. Symbol VTH Parameter Differential Input High Conditions Min Typ VO = 2.7V, IO = −0.4 mA Threshold Voltage VTL Differential Input Low VO = 0.5V, IO = 8.0 mA Max Units 0.2 V −0.2 Threshold Voltage (Note 6) V VT+−VT− Hysteresis (Note 7) VCM = 0V 35 VIH Enable Input Voltage HIGH RE 2.0 VIL Enable Input Voltage LOW 0.8 V VIC Enable Input Clamp Voltage II = −18 mA -0.8 -1.3 V IIH Input Current HIGH VIH = 2.7V 1 20 μA IIL Input Current LOW VIL = 0.4V -3 -50 μA VOH Output Voltage HIGH (RO) VID = 200 mV, IOH = −400 μA, Figure 2 VOL Output Voltage LOW (RO) VID = −200 mV, IOL = 8.0 mA 0.3 0.45 Figure 2 IOL = 16 mA 0.4 0.50 IOS Short Circuit Output Current (RO) IOZ High Impedance State Output (RO) VO = 0.4V to 2.4V II Line Input Current (Note 8) RI Input Resistance VO = 0V, (Note 9) 2.5 -15 50 mV V 3.5 V -46 -85 mA 0.2 ±20 μA A or B, Other Input = 0V VI = +12V 0.57 1.5 VI = −7.0V -0.43 -0.8 A or B DE = 0.4V 18 22 3 12 V mA kΩ www.national.com DS16F95A Driver Switching Characteristics DS16F95A Receiver Switching Characteristics (Note 2) Over recommended supply voltage and operating temperature ranges, unless otherwise specified. Symbol tPLH Parameter Propagation Delay Time, Low-to-High Level Output tPHL Conditions Min Typ Max Units VIN = 0V to +3.0V CL = 15 pF, Figure 6 10 19 50 ns 10 19 50 ns 10 75 ns 12 75 ns CL = 5.0 pF, Figure 7 12 50 ns 12 50 ns Figure 6 1.0 16 ns Propagation Delay Time, High-to-Low Level Output tZH Output Enable Time to High Level tZL Output Enable Time to Low Level tHZ Output Disable Time from High Level tLZ Output Disable Time from Low Level |tPLH−tPHL| Pulse Width Distortion (SKEW) CL = 15 pF, Figure 7 Device Electrical Characteristics (Notes 2, 3) Over recommended supply voltage and operating temperature ranges, unless otherwise specified. Symbol ICC Parameter Supply Current (Total Package) Conditions Min No Load, DE = 2V, RE = 0.8V All Inputs Open Outputs Enabled ICCX DE = 0.8V, RE = 2V Outputs Disabled Typ Max 21.5 28 16 25 Units mA Note 1: “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 tables of “Electrical Characteristics” provide conditions for actual device operation. Note 2: Unless otherwise specified min/max limits apply across the -55°C to +180°C temperature range for the DS16F95A. All typical values are given for VCC = 5V and TA = 25°C. Note 3: All currents into the device pins are positive; all currents out of the device pins are negative. All voltages are referenced to ground unless otherwise specified. Note 4: Δ|VOD| and Δ|VOC| are the changes in magnitude of VOD and VOC, respectively, that occur when the input is changed from a high level to a low level. Note 5: In TIA/EIA-422-B and TIA/EIA-485-A Standards, VOC, which is the average of the two output voltages with respect to ground, is called output offset voltage, VOS. Note 6: The algebraic convention, where the less positive (more negative) limit is designated minimum, is used in this data sheet for common mode input voltage and threshold voltage levels only. Note 7: Hysteresis is the difference between the positive-going input threshold voltage, VT+, and the negative-going input threshold voltage, VT−. Note 8: Refer to TIA/EIA-485-A Standard for exact conditions. Note 9: Only one output at a time should be shorted. Do not exceed maximum junction temperature recommendations. This device does not include thermal shutdown protection. Note 10: Lifetime expectations for continuous operation at above 150 °C for more than 1000 hours should be verified with National Semiconductor Reliability Engineering. Reliability report available upon request. Note 11: ESD Rating information: HBM >5kV A or B pin, all other pins > 1kV. MM > 600V A or B pin, all other pins > 50V, CDM >750V, IEC61000–4–2 (Power On or Off) > 2kV A or B pin. Parameter Measurement Information 30066702 FIGURE 1. Driver VOD and VOC (Note 15) www.national.com 4 DS16F95A 30066703 FIGURE 2. Receiver VOH and VOL 30066704 30066705 tSKEW = |tPLHD–tPHLD| FIGURE 3. Driver Differential Output Delay and Transition Times (Notes 12, 14) 30066709 30066708 FIGURE 4. Driver Enable and Disable Times (tZH, tHZ) (Notes 12, 13, 14) 30066711 30066710 FIGURE 5. Driver Enable and Disable Times (tZL, tLZ, tLZL) (Notes 12, 13, 14) 5 www.national.com DS16F95A 30066713 30066712 FIGURE 6. Receiver Propagation Delay Times (Notes 12, 13) 30066714 30066715 30066717 30066716 30066718 FIGURE 7. Receiver Enable and Disable Times (Notes 12, 13, 15) Note 12: The input pulse is supplied by a generator having the following characteristics: PRR = 1.0 MHz, 50% duty cycle, tr ≤ 6.0 ns, tf ≤ 6.0 ns, ZO = 50Ω. Note 13: CL includes probe and stray capacitance. Note 14: DS16F95A Driver enable is Active-High. Note 15: All diodes are 1N916 or equivalent. Note 16: Testing at 20 pF assures conformance to 5 pF specification. www.national.com 6 The Differential Line Driver levels shifts standard TTL/CMOS levels to a differential voltage on the bus pins (A and B) that conform to RS-485. The driver is enabled when the DE pin is High. The driver is disabled when the DE pin is Low. The DI and DE pins should be driven or tied to the desired state, do not float. The differential driver is able to source and sink up to 60mA of output current. Care should be taken that the driver is not enabled into a fault condition where the package power dissipation capacity is exceeded. The DS16F95A features driver current limiting (see IOS specification) to protect from certain line faults where the amount of power is limited. This device is intended for use in rugged applications at elevated temperatures. It does not include a Thermal Shutdown feature commonly found on RS-485 transceivers. The Differential line Receiver levels shifts the RS-485 levels to standard TTL/CMOS levels. The receiver is enabled when the RE pin is Low. The receiver is disabled when the RE pin is High. The RE pin should be driven or tied to the desired state, do not float. Typical Application A typical application is shown below. The RS-485 network may be a simple point-to-point connection with two nodes or a more complex one with up to 32 single unit load transceivers as shown above. Stub lengths off the main line should be kept as short as possible to minimize reflections. The line is ter- 30066719 Connection Diagram 8-Lead Dual-In-Line Package 30066701 7 www.national.com DS16F95A minated at both ends in its characteristic impedance (typically 100 or 120 Ohms). The RS-485 network is a bi-directional half duplex interface. Being a multipoint bus, it is possible for all drivers to be disabled when one or more receivers are enabled. In this case, the receiver(s) is enabled when a valid differential voltage is not present and its output state is unknown. A common solution is to provide external failsafe biasing to bias the line to a known state such that the enabled receives will detect it correctly and idle with a static known state in this condition. See AN-847 for a discussion on Failsafe biasing of differential buses. For extended temperature applications, maximum junction temperature should be calculated. TJmax = TA + (ThetaJA) (Power Dissipation). Theta JA is the reciprocal of the derate term ( 1 / 8.7 mW/°C or 115 °C/W). Recommended maximum junction temperature for short duration operation is 200°C. See AN-336 for a discussion on thermal considerations. For maximum performance, a few system / PCB recommendations are: drive the logic inputs (DI, DE, RE) with rail-to-rail levels. This will provide the maximum noise margins to the thresholds. A clean supply is also desirable, a 0.1µF capacitor is recommended to be placed near the VCC pin along with a bulk capacitor. The use of power and ground planes is also recommended. Stub lengths off the RS-485 interface should be minimized to limit reflections. Typical interconnect impedance is 100 Ohms. Functional Description DS16F95A Physical Dimensions inches (millimeters) unless otherwise noted 8 Narrow Lead Ceramic Dual-In-Line Package (J) Order Number DS16F95AJA NS Package Number J08A www.national.com 8 DS16F95A Notes 9 www.national.com DS16F95A TIA/EIA-485-A (RS-485) Extended Temperature Differential Bus Transceiver Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage Reference www.national.com/vref Design Made Easy www.national.com/easy PowerWise® Solutions www.national.com/powerwise Solutions www.national.com/solutions Serial Digital Interface (SDI) www.national.com/sdi Mil/Aero www.national.com/milaero Temperature Sensors www.national.com/tempsensors Solar Magic® www.national.com/solarmagic Wireless (PLL/VCO) www.national.com/wireless Analog University® www.national.com/AU THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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