DS8925 LocalTalk™ Dual Driver/Triple Receiver General Description Features The DS8925 is a dual driver/triple receiver device optimized to provide a single chip solution for a LocalTalk Interface. The device provides one differential TIA/EIA-422 driver, one TIA/EIA-423 single ended driver, one TIA/EIA-422 receiver and two TIA/EIA-423 receivers, all in a surface mount 16 pin package. This device is electrically similar to the 26LS30 and 26LS32 devices. The drivers feature ± 10V common mode range, and the differential driver provides TRI-STATEable outputs. The receivers offer ± 200 mV thresholds over the ± 10V common mode range. n n n n n n Connection Diagram Functional Diagram Single chip solution for LocalTalk port Two driver/three receivers per package Wide common mode range: ± 10V ± 200 mV receiver sensitivity 70 mV typical receiver input hysteresis Available in SOIC packaging Dual-In-Line Package DS011895-1 Order Number DS8925M See NS Package Number M16A DS011895-2 TRI-STATE ® is a registered trademark of National Semiconductor Corporation. LocalTalk™ is a trademark of Apple Computer Incorporated. © 1998 National Semiconductor Corporation DS011895 www.national.com DS8925 LocalTalk Dual Driver/Triple Receiver December 1998 Absolute Maximum Ratings (Note 1) Derate M Package 10.6 mW/˚C above +25˚C Storage Temperature Range Lead Temperature Range (Soldering, 4 Sec.) This Device Does Not Meet 2000V ESD Rating If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (VCC) Supply Voltage (VEE) Enable Input Voltage (DEN1) Driver Input Voltage (DIN) Driver Output Voltage (Power Off: DOUT) Receiver Input Voltage (VID: RIN+ − RIN−) Receiver Input Voltage (VCM: (RIN+ + RIN−)/2) Receiver Input Voltage (Input to GND: RIN) Receiver Output Voltage (ROUT) Maximum Package Power Dissipation @ +25˚C M Package +7V −7V +7V +7V ± 15V −65˚C to +150˚C +260˚C (Note 7) Recommended Operating Conditions ± 25V Supply Voltage (VCC) Supply Voltage (VEE) Operating Free Air Temperature (TA) ± 25V ± 25V +5.5V Min +4.75 −4.75 Typ +5.0 −5.0 Max +5.25 −5.25 Units V V 0 25 70 ˚C Min Typ Max Units ±7 ± 9.0 ± 4.5 ± 10 ± 5.25 V 4.0 6.4 8.0 12.8 1.33W Electrical Characteristics (Notes 2, 3) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Pin DIFFERENTIAL DRIVER CHARACTERISTICS VOD Output Differential Voltage VO Output Voltage VOD1 Output Differential Voltage VSS |VOD1 − VOD1*| ∆VOD1 Output Unbalance VOS Offset Voltage ∆VOS Offset Unbalance VOD2 Output Differential Voltage IOZD TRI-STATE ® Leakage Current RL = ∞ or RL = 3.9 kΩ RL = ∞ or RL = 3.9 kΩ RL = 100Ω, Figure 1 DOUT+, DOUT− RL = 140Ω, Figure 1 VCC = 5.25V VO = +10V VEE = −5.25V VO = +6V VO = −6V VO = −10V 6.0 V |V| |V| 0.02 0.4 0 3 V 0.05 0.4 V 150 µA 7.0 2 V |V| 1 100 µA −1 −100 µA −2 −150 µA 4 4.4 6 3.7 4.3 SINGLE ENDED DRIVER CHARACTERISTICS VO Output Voltage (No Load) VT Output Voltage ∆VT Output Unbalance RL = ∞ or RL = 3.9 kΩ, Figure 2 RL = 3 kΩ, Figure 2 RL = 450Ω, Figure 2 DOUT− 3.6 |V| |V| 4.1 |V| 0.02 0.4 V −80 −150 mA 80 150 mA 2 150 µA 1 100 µA −1 −100 µA −2 −150 µA DRIVER CHARACTERISTICS VCM Common Mode Range IOSD Short Circuit Current Power Off, or D1 Disabled VO = 0V, Sourcing Current IOXD Power-Off Leakage Current (VCC = VEE = 0V) VO = 0V, Sinking Current VO = +10V VO = +6V VO = −6V VO = −10V www.national.com 2 ± 10 DOUT+, DOUT− V Electrical Characteristics (Notes 2, 3) (Continued) Over Supply Voltage and Operating Temperature ranges, unless otherwise specified Symbol Parameter Conditions Pin Min Typ Max Units −200 ± 35 +200 mV RECEIVER CHARACTERISTICS VTH Input Threshold VHY Hysteresis RIN Input Resistance IIN Input Current (Other Input = 0V, Power On, or VCC = VEE = 0V) −7V ≤ VCM ≤ +7V VCM = 0V −10V ≤ VCM ≤ +10V VIN = +10V VIN = +3V VIN = −3V VIN = −10V VIB Input Balance Test VOH High Level Output Voltage RS = 500Ω (R2 only) IOH = −400 µA, VIN = +200 mV VOL Low Level Output Voltage IOSR Short Circuit Current IOH = −400 µA, VIN = OPEN IOL = 8.0 mA, VIN = −200 mV VO = 0V 70 6.0 RIN+, RIN− kΩ 3.25 mA 0 1.50 mA 0 −1.50 mA 2.7 ROUT mV 8.5 2.7 −15 −3.25 mA ± 400 mV 4.2 V 4.2 V 0.3 0.5 V −34 −85 mA DEVICE CHARACTERISTICS VIH High Level Input Voltage VIL Low Level Input Voltage IIH High Level Input Current IIL Low Level Input Current VIN = 2.4V VIN = 0.4V VCL Input Clamp Voltage IIN = −12 mA ICC Power Supply Current No Load VCC D1 Enabled or Disabled VEE IEE 2.0 DIN, DEN1 3 V 0.8 V 1 40 µA −10 −200 µA −1.5 V 40 65 mA −5 −15 mA www.national.com Switching Characteristics (Notes 4, 5) Over Supply Voltage and Operating Temperature Ranges, unless otherwise specified Symbol Parameter Conditions Min Typ Max Units 70 134 350 ns 70 141 350 ns 7 50 ns ns DIFFERENTIAL DRIVER CHARACTERISTICS RL = 100Ω, CL = 500 pF, (Figures 3, 4) C1 = C2 = 50 pF tPHLD Differential Propagation Delay High to Low tPLHD Differential Propagation Delay Low to High tSKD Differential Skew |tPHLD − tPLHD| tr Rise Time 50 140 300 tf Fall Time 50 140 300 ns tPHZ Disable Time High to Z 300 600 ns tPLZ Disable Time Low to Z 300 600 ns tPZH Enable Time Z to High 160 350 ns tPZL Enable Time Z to Low 160 350 ns 70 120 350 ns 70 150 350 ns 30 70 ns RL = 100Ω, CL = 500 pF (Figures 7, 8) SINGLE ENDED DRIVER CHARACTERISTICS RL = 450Ω, CL = 500 pF (Figures 5, 6) tPHL Propagation Delay High to Low tPLH Propagation Delay Low to High tSK Skew, |tPHL − tPLH tr Rise Time 50 100 300 ns tf Fall Time 20 50 300 ns 10 33 75 ns 10 30 75 ns 3 20 ns RECEIVER CHARACTERISTICS tPHL Propagation Delay High to Low tPLH Propagation Delay Low to High tSK Skew, |tPHL − tPLH| CL = 15 pF (Figures 9, 10) 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 table of Electrical Characteristics specifies conditions of device operation. Note 2: Current into device pins is defined as positive. Current out of device pins is defined as negative. All voltages are referenced to ground except VOD, VOD1, VOD2, and VSS. Note 3: All typicals are given for: VCC = +5.0V, VEE = −5.0V, TA = +25˚C unless otherwise specified. Truth Tables Receiver (1) Driver (D1) Inputs Outputs DEN1 DIN1 DOUT1+ DOUT1− H X Z Z L L L H L H H L Output DIN2 DOUT2− L H H L ROUT1 ≤−200 mV H ≥+200 mV L OPEN† H Inputs Output RIN2+ − RIN2− ROUT2 ≤−200 mV L ≥+200 mV H OPEN† H Receiver (3) H = Logic High Level (Steady State) L = Logic Low Level (Steady State) X = Irrelevant (Any Input) Z = Off State (TRI-STATE, High Impedance) † OPEN = Non-Terminated www.national.com Output Receiver (2) Driver (D2) Input Input RIN1− 4 Input Output RIN3+ ROUT3 ≤−200 mV L ≥+200 mV H OPEN† H Parameter Measurement Information DS011895-3 FIGURE 1. Differential Driver DC Test Circuit DS011895-4 FIGURE 2. Single Ended Driver DC Test Circuit DS011895-5 FIGURE 3. Differential Driver Propagation Delay and Transition Time Test Circuit DS011895-6 FIGURE 4. Differential Driver Propagation Delay and Transition Time Waveforms DS011895-7 FIGURE 5. Single Ended Driver Propagation Delay and Transition Time Test Circuit 5 www.national.com Parameter Measurement Information (Continued) DS011895-8 FIGURE 6. Single Ended Driver Propagation Delay and Transition Time Waveform DS011895-9 FIGURE 7. Differential Driver TRI-STATE Test Circuit DS011895-10 FIGURE 8. Differential Driver TRI-STATE Waveforms DS011895-11 FIGURE 9. Receiver Propagation Delay Test Circuit www.national.com 6 Parameter Measurement Information (Continued) DS011895-12 Note 4: Generator waveform for all tests unless otherwise specified: f = 500 kHz, ZO = 50Ω, tr ≤ 10 ns, tf ≤ 10 ns. Note 5: CL includes probe and jig capacitance. Note 6: All diodes are 1N916 or equivalent. Note 7: ESD Rating HBM (1.5 kΩ, 100 pF) pins 10, 12 ≥ 1500V, all other pins ≥ 2000V. FIGURE 10. Receiver Propagation Delay Waveform Typical Application Information DS011895-13 FIGURE 11. Typical LocalTalk Application TABLE 1. Device Pin Descriptions Pin# 2, 4 Name Description DIN TTL Driver Input Pins 3 DEN1 Active Low Driver Enable Pin. A High on this Pin TRI-STATES the Driver Outputs (D1 Only) 15 DOUT+ Non-Inverting Driver Output Pin 13, 14 DOUT− Inverting Driver Output Pin 9, 11 RIN+ Non-Inverting Receiver Input Pin 10, 12 RIN− Inverting Receiver Input Pin 5, 6, 7 ROUT Receiver Output Pin 8 GND Ground Pin 1 VEE Negative Power Supply Pin, −5V ± 5% 16 VCC Positive Power Supply Pin, +5V ± 5% 7 www.national.com Typical Application Information left floating as this may lead to unwanted switching which may affect ICC, particularly the frequency component. Unused driver inputs should be tied to ground. (Continued) DRIVER OUTPUT WAVEFORMS Receiver outputs will be in a HIGH state when inputs are open; therefore, outputs should not be tied to ground. It is best to leave unused receiver outputs floating. The driver configuration on the DS8925 is unique among TIA/EIA-422 devices in that it utilizes −5V VEE supply. A typical TIA/EIA-422 driver uses +5V only and generates signal swings of approximately 0V–5V. RECEIVER FAILSAFE All three receivers on this device incorporate open input failsafe protection. The differential receiver output will be in a HIGH state when inputs are open, but will be indetermined if inputs are shorted together. Unused differential inputs should be left floating. Both single-ended receivers (inverting and non-inverting) are biased internally so that an open input will result in a HIGH output. Therefore, these inputs should not be shorted to ground when unused. By utilizing VEE, the differential driver is able to generate a much larger differential signal. The typical output voltage is about |4| V, which gives |8| V differentially, thus providing a much greater noise margin than +5V drivers. See Figure 12. The receiver therefore has a range of +8V to −8V or VSS of 16V (VSS = VOD–VOD*). Each side of the differential driver operates similar to a TIA/ EIA-423 driver. The output voltages are slightly different due to the loading: the differential driver has differential termination, the single-ended driver is terminated with a resistor to ground. BYPASS CAPACITORS Bypass capacitors are recommended for both VCC and VEE. Noise induced on the supply lines can affect the signal quality of the output; VCC affects the VOH and VEE affects the VOL. Capacitors help reduce the effect on signal quality. A value of 0.1 µF is typically used. Since this is a power device, it is recommended to use a bypass capacitor for each supply and for each device. Sharing a bypass capacitor between other devices may not be sufficient. TERMINATION On a multi-point transmission line which is electrically long, it is advisable to terminate the line at both ends with its characteristic impedance to prevent signal reflection and its associated noise/crosstalk. A 100Ω termination resistor is commonly specified by TIA/ EIA-422 for differential signals. The DS8925 is also specified using 140Ω termination which will result in less power associated with the driver output. The additional resistance is typical of applications requiring EMI filtering on the driver outputs. DS011895-15 Note 8: Star (*) represents the opposite input condition for a parameter. FIGURE 12. Typical Driver Output Waveforms TWO-WIRE LocalTalk The DS8925 is a single chip solution for a LocalTalk interface. A typical application is shown in Figure 11. UNUSED PINS Unused driver outputs should be left open. If tied to either ground or supply, the driver may enter an IOS state and consume excessive power. Unused driver inputs should not be www.national.com An alternative implementation of LocalTalk is to only use two wires to communicate. The differential data lines can be transformer-coupled on to a twisted pair medium. See Figure 13. The handshake function must then be accomplished in software. 8 Typical Application Information (Continued) DS011895-16 Note 9: Star (*) represents the opposite input condition for a parameter. FIGURE 13. Differential Communication, Transformer-Coupled to a Twisted-Pair Line state will be near 0V instead of VEE. Thus, the output would switch from about 4V to 0V, instead of 4V to −4V. The differential driver will meet TIA/EIA-422, but with a reduced noise margin. The single-ended driver will not meet TIA/EIA-423 without the −5V supply. The receivers will be functional but may suffer parametrically. The inverting receiver is referenced to VEE therefore, the threshold may shift slightly. The inputs can still vary over the ± 10V common mode range. SINGLE +5V SUPPLY The DS8925 is derived from the DS3691/92 which could be configured using a single +5V supply (VEE = 0V). This device is not specified for this type of operation. However, the device will not be damaged if operated using a single +5V supply. Both drivers require the −5V supply in order to meet the output voltage levels specified. When the device switches from a positive voltage to the complimentary state, it is pulled toward the VEE level. If that level is 0V, then the complimentary Typical Performance Characteristics Differential Driver Output Voltage vs Output Current (Note 10) Differential Driver Output Voltage vs Output Current DS011895-17 DS011895-18 9 www.national.com Typical Performance Characteristics Differential Driver Propagation Delay vs Temperature (Note 10) (Continued) Differential Driver Propagation Delay vs Power Supply Voltage DS011895-19 Differential Driver Skew vs Temperature DS011895-20 Differential Driver Skew vs Power Supply Voltage DS011895-21 Differential Transition Time vs Temperature DS011895-22 Differential Transition Time vs Power Supply Voltage DS011895-23 www.national.com DS011895-24 10 Typical Performance Characteristics Driver Output High Voltage vs Output High Current (Note 10) (Continued) Driver Output High Voltage vs Output High Current DS011895-25 Driver Output Low Voltage vs Output Low Current DS011895-26 Driver Output Low Voltage vs Output Low Current DS011895-27 Driver Propagation Delay vs Temperature DS011895-28 Driver Propagation Delay vs Power Supply Voltage DS011895-30 DS011895-29 11 www.national.com Typical Performance Characteristics (Note 10) (Continued) Driver Skew vs Power Supply Voltage Driver Skew vs Temperature DS011895-31 Driver Transition Time vs Temperature DS011895-32 Driver Transition Time vs Power Supply Voltage DS011895-33 Receiver Output High Voltage vs Output High Current DS011895-34 Receiver Output High Voltage vs Output High Current DS011895-35 www.national.com DS011895-36 12 Typical Performance Characteristics Receiver Output Low Voltage vs Output Low Current (Note 10) (Continued) Receiver Output Low Voltage vs Output Low Current DS011895-37 Receiver Input Current vs Input Voltage (Power On) DS011895-38 Receiver Input Current vs Input Voltage (Power Off) DS011895-39 Receiver Output Propagation Delay vs Temperature DS011895-40 Receiver Output Propagation Delay vs Power Supply Voltage DS011895-41 DS011895-42 13 www.national.com Typical Performance Characteristics Receiver Output Skew vs Temperature (Note 10) (Continued) Receiver Output Skew vs Power Supply Voltage DS011895-43 Supply Current vs Power Supply Voltage DS011895-44 Supply Current vs Power Supply Voltage DS011895-45 DS011895-46 Note 10: V defined as VCC = |VEE| www.national.com 14 15 DS8925 LocalTalk Dual Driver/Triple Receiver Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead (0.150") Wide Molded Small Outline Package, JEDEC Order Number DS8925M NS Package Number M16A 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. 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