DS90LV049 3V LVDS Dual Line Driver with Dual Line Receiver General Description Features The DS90LV049 is a dual CMOS flow-through differential line driver-receiver pair designed for applications requiring ultra low power dissipation, exceptional noise immunity, and high data throughput. The device is designed to support data rates in excess of 400 Mbps utilizing Low Voltage Differential Signaling (LVDS) technology. n n n n n n n n n n n n The DS90LV049 drivers accept LVTTL/LVCMOS signals and translate them to LVDS signals. On the other hand, the receivers accept LVDS signals and translate them to 3 V CMOS signals. The LVDS input buffers have internal failsafe biasing that places the outputs to a known H (high) state for floating receiver inputs. In addition, the DS90LV049 supports a TRI-STATE function for a low idle power state when the device is not in use. Up to 400 Mbps switching rates Flow-through pinout simplifies PCB layout 50 ps typical driver channel-to-channel skew 50 ps typical receiver channel-to-channel skew 3.3 V single power supply design TRI-STATE output control Internal fail-safe biasing of receiver inputs Low power dissipation (70 mW at 3.3 V static) High impedance on LVDS outputs on power down Conforms to TIA/EIA-644-A LVDS Standard Industrial operating temperature range (−40˚C to +85˚C) Available in low profile 16 pin TSSOP package The EN and EN inputs are ANDed together and control the TRI-STATE outputs. The enables are common to all four gates. Connection Diagram Functional Diagram Dual-In-Line 20042001 Order Number DS90LV049TMT Order Number DS90LV049TMTX (Tape and Reel) See NS Package Number MTC16 20042002 Truth Table EN EN LVDS Out LVCMOS Out L or Open L or Open OFF OFF H L or Open ON ON L or Open H OFF OFF H H OFF OFF © 2003 National Semiconductor Corporation DS200420 www.national.com DS90LV049 3V LVDS Dual Line Driver with Dual Line Receiver March 2003 DS90LV049 Absolute Maximum Ratings Lead Temperature Range (Note 1) Soldering (4 sec.) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (VDD) MTC Package −0.3 V to (VDD + 0.3 V) LVDS Input Voltage (RIN+, RIN-) 866 mW Derate MTC Package −0.3 V to +3.9 V 6.9 mW/˚C above +25˚C ESD Rating Enable Input Voltage (EN, EN) −0.3 V to (VDD + 0.3 V) (HBM, 1.5 kΩ, 100 pF) LVCMOS Output Voltage (DIN) −0.3 V to (VDD + 0.3 V) (MM, 0 Ω, 200 pF) LVDS Output Voltage (DOUT+, DOUT-) −0.3 V to +3.9 V 100 mA LVDS Output Short Circuit Current (DOUT+, DOUT−) Supply Voltage (VDD) 24 mA ≥ 250 V Min Typ Max Units +3.0 +3.3 +3.6 V −40 +25 +85 ˚C Operating Free Air LVDS Output Short Circuit Current Duration(DOUT+, DOUT−) Storage Temperature Range ≥ 7 kV Recommended Operating Conditions LVCMOS Output Short Circuit Current (ROUT) +150˚C Maximum Package Power Dissipation @ +25˚C −0.3 V to +4 V LVCMOS Input Voltage (DIN) +260˚C Maximum Junction Temperature Temperature (TA) Continuous −65˚C to +150˚C Electrical Characteristics Over supply voltage and operating temperature ranges, unless otherwise specified. (Notes 2, 4, 6) Symbol Parameter Conditions Pin Min Typ Max Units VDD V LVCMOS Input DC Specifications (Driver Inputs, ENABLE Pins) VIH Input High Voltage VIL Input Low Voltage IIH Input High Current IIL Input Low Current VIN = GND VCL Input Clamp Voltage ICL = −18 mA 2.0 DIN EN EN VIN = VDD GND −10 0.8 V 1 +10 µA +10 µA −10 −0.1 −1.5 −0.6 250 350 450 mV 1 35 |mV| 1.23 1.375 V 1 25 |mV| −5.8 −9.0 mA −5.8 −9.0 mA V LVDS Output DC Specifications (Driver Outputs) | VOD | Differential Output Voltage ∆VOD Change in Magnitude of VOD for Complementary Output States RL = 100 Ω (Figure 1) VOS Offset Voltage ∆VOS Change in Magnitude of VOS for Complementary Output States IOS Output Short Circuit Current (Note 14) IOSD Differential Output Short Circuit Current (Note 14) IOFF Power-off Leakage VOUT = 0 V or 3.6 V VDD = 0 V or Open −20 ±1 +20 µA IOZ Output TRI-STATE Current EN = 0 V and EN = VDD VOUT = 0 V or VDD −10 ±1 +10 µA −15 35 mV 1.125 ENABLED, DIN = VDD, DOUT+ = 0 V or DIN = GND, DOUT− = 0 V DOUT− DOUT+ ENABLED, VOD = 0 V LVDS Input DC Specifications (Receiver Inputs) VTH Differential Input High Threshold VTL Differential Input Low Threshold VCMR Common-Mode Voltage Range IIN Input Current www.national.com VCM = 1.2 V, 0.05 V, 2.35 V -100 VID = 100 mV, VDD=3.3 V VDD=3.6 V VIN =0 V or 2.8 V VDD=0 V VIN =0 V or 2.8 V or 3.6 V 2 −15 0.05 RIN+ RIN- mV 3 V −12 ±4 +12 µA −10 ±1 +10 µA (Continued) Over supply voltage and operating temperature ranges, unless otherwise specified. (Notes 2, 4, 6) Symbol Parameter Conditions Pin Min Typ Max Units 0.05 0.25 V ±1 +10 µA 21 35 mA 15 25 mA Typ Max Units LVCMOS Output DC Specifications (Receiver Outputs) VOH Output High Voltage IOH = -0.4 mA, VID= 200 mV VOL Output Low Voltage IOL = 2 mA, VID = 200 mV IOZ Output TRI-STATE Current Disabled, VOUT =0 V or VDD 2.7 ROUT -10 3.3 V General DC Specifications IDD Power Supply Current (Note 3) EN = 3.3 V IDDZ TRI-State Supply Current EN = 0 V VDD Switching Characteristics VDD = +3.3V ± 10%, TA = −40˚C to +85˚C (Notes 4, 13) Symbol Parameter Conditions Min LVDS Outputs (Driver Outputs) tPHLD Differential Propagation Delay High to Low 0.7 2 ns tPLHD Differential Propagation Delay Low to High 0.7 2 ns tSKD1 Differential Pulse Skew |tPHLD − tPLHD| (Notes 5, 7) 0 0.05 0.4 ns tSKD2 Differential Channel-to-Channel Skew (Notes 5, 8) 0 0.05 0.5 ns tSKD3 Differential Part-to-Part Skew (Notes 5, 9) 1.0 ns tTLH Rise Time (Note 5) 0.2 0.4 1 ns tTHL Fall Time (Note 5) 0.2 0.4 1 ns tPHZ Disable Time High to Z 1.5 3 ns tPLZ Disable Time Low to Z tPZH Enable Time Z to High tPZL Enable Time Z to Low fMAX Maximum Operating Frequency (Note 16) RL = 100 Ω (Figure 2 and Figure 3) 0 RL = 100 Ω (Figure 4 and Figure 5) 1.5 3 ns 3 6 ns 1 3 6 200 250 1 ns MHz LVCMOS Outputs (Receiver Outputs) tPHL Propagation Delay High to Low 0.5 2 3.5 ns tPLH Propagation Delay Low to High 0.5 2 3.5 ns tSK1 Pulse Skew |tPHL − tPLH| (Note 10) tSK2 Channel-to-Channel Skew (Note 11) tSK3 Part-to-Part Skew (Note 12) tTLH Rise Time(Note 5) 0.3 tTHL Fall Time(Note 5) 0.3 tPHZ Disable Time High to Z 3 5.6 8 ns tPLZ Disable Time Low to Z 3 5.4 8 ns tPZH Enable Time Z to High 2.5 4.6 7 ns tPZL Enable Time Z to Low 2.5 4.6 7 fMAX Maximum Operating Frequency (Note 17) 200 250 (Figure 6 and Figure 7) 0 0.05 0.4 ns 0 0.05 0.5 ns 1.0 ns 0.9 1.4 ns 0.75 1.4 ns 0 (Figure 8 and Figure 9) ns MHz 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: VTH, VTL, VOD and ∆VOD. Note 3: Both, driver and receiver inputs are static. All LVDS outputs have 100 Ω load. All LVCMOS outputs are floating. None of the outputs have any lumped capacitive load. Note 4: All typical values are given for: VDD = +3.3 V, TA = +25˚C. Note 5: These parameters are guaranteed by design. The limits are based on statistical analysis of the device performance over PVT (process, voltage, temperature) ranges. Note 6: The DS90LV049’s drivers are current mode devices and only function within datasheet specifications when a resistive load is applied to their outputs. The typical range of the resistor values is 90 Ω to 110 Ω. Note 7: tSKD1 or differential pulse skew is defined as |tPHLD − tPLHD|. It is the magnitude difference in the differential propagation delays between the positive going edge and the negative going edge of the same driver channel. 3 www.national.com DS90LV049 Electrical Characteristics DS90LV049 Switching Characteristics (Continued) Note 8: tSKD2 or differential channel-to-channel skew is defined as the magnitude difference in the differential propagation delays between two driver channels on the same device. Note 9: tSKD3 or differential part-to-part skew is defined as |tPLHD Max − tPLHD Min| or |tPHLD Max − tPHLD Min|. It is the difference between the minimum and maximum specified differential propagation delays. This specification applies to devices at the same VDD and within 5˚C of each other within the operating temperature range. Note 10: tSK1 or pulse skew is defined as |tPHL − tPLH|. It is the magnitude difference in the propagation delays between the positive going edge and the negative going edge of the same receiver channel. Note 11: tSK2 or channel-to-channel skew is defined as the magnitude difference in the propagation delays between two receiver channels on the same device. Note 12: tSK3 or part-to-part skew is defined as |tPLH Max − tPLH Min| or |tPHL Max − tPHL Min|. It is the difference between the minimum and maximum specified propagation delays. This specification applies to devices at the same VDD and within 5˚C of each other within the operating temperature range. Note 13: Generator waveform for all tests unless otherwise specified: f = 1 MHz, ZO = 50 Ω, tr ≤ 1 ns, and tf ≤ 1 ns. Note 14: Output short circuit current (IOS) is specified as magnitude only, minus sign indicates direction only. Note 15: All input voltages are for one channel unless otherwise specified. Other inputs are set to GND. Note 16: fMAX generator input conditions: tr = tf < 1 ns (0% to 100%), 50% duty cycle, 0 V to 3 V. Output Criteria: duty cycle = 45%/55%, VOD > 250 mV, all channels switching. Note 17: fMAX generator input conditions: tr = tf < 1 ns (0% to 100%), 50% duty cycle, VID = 200 mV, VCM = 1.2 V . Output Criteria: duty cycle = 45%/55%, VOH > 2.7 V, VOL < 0.25 V, all channels switching. Parameter Measurement Information 20042003 FIGURE 1. Driver VOD and VOS Test Circuit 20042004 FIGURE 2. Driver Propagation Delay and Transition Time Test Circuit www.national.com 4 DS90LV049 Parameter Measurement Information (Continued) 20042005 FIGURE 3. Driver Propagation Delay and Transition Time Waveforms 20042006 FIGURE 4. Driver TRI-STATE Delay Test Circuit 5 www.national.com DS90LV049 Parameter Measurement Information (Continued) 20042007 FIGURE 5. Driver TRI-STATE Delay Waveform 20042009 FIGURE 6. Receiver Propagation Delay and Transition Time Test Circuit 20042010 FIGURE 7. Receiver Propagation Delay and Transition Time Waveforms www.national.com 6 DS90LV049 Parameter Measurement Information (Continued) 20042011 FIGURE 8. Receiver TRI-STATE Delay Test Circuit 20042014 FIGURE 9. Receiver TRI-STATE Delay Waveforms Typical Application 20042008 FIGURE 10. Point-to-Point Application 7 www.national.com DS90LV049 magnetic field cancellation is much better with the closer traces. In addition, noise induced on the differential lines is much more likely to appear as common-mode which is rejected by the receiver. Match electrical lengths between traces to reduce skew. Skew between the signals of a pair means a phase difference between signals which destroys the magnetic field cancellation benefits of differential signals and EMI will result. (Note the velocity of propagation, v = c/Er where c (the speed of light) = 0.2997 mm/ps or 0.0118 in/ps). Do not rely solely on the autoroute function for differential traces. Carefully review dimensions to match differential impedance and provide isolation for the differential lines. Minimize the number or vias and other discontinuities on the line. Applications Information General application guidelines and hints for LVDS drivers and receivers may be found in the following application notes: LVDS Owner’s Manual (lit #550062-002), AN-805, AN-808, AN-903, AN-916, AN-971, AN-977. LVDS drivers and receivers are intended to be primarily used in an uncomplicated point-to-point configuration as is shown in Figure 10. This configuration provides a clean signaling environment for the fast edge rates of the drivers. The receiver is connected to the driver through a balanced media which may be a standard twisted pair cable, a parallel pair cable, or simply PCB traces. Typically, the characteristic differential impedance of the media is in the range of 100 Ω. A termination resistor of 100 Ω (selected to match the media), and is located as close to the receiver input pins as possible. The termination resistor converts the driver output current (current mode) into a voltage that is detected by the receiver. Other configurations are possible such as a multireceiver configuration, but the effects of a mid-stream connector(s), cable stub(s), and other impedance discontinuities as well as ground shifting, noise margin limits, and total termination loading must be taken into account. The TRI-STATE function allows the device outputs to be disabled, thus obtaining an even lower power state when the transmission of data is not required. The DS90LV049 has a flow-through pinout that allows for easy PCB layout. The LVDS signals on one side of the device easily allows for matching electrical lengths of the differential pair trace lines between the driver and the receiver as well as allowing the trace lines to be close together to couple noise as common-mode. Noise isolation is achieved with the LVDS signals on one side of the device and the TTL signals on the other side. Avoid 90˚ turns (these cause impedance discontinuities). Use arcs or 45˚ bevels. Within a pair of traces, the distance between the two traces should be minimized to maintain common-mode rejection of the receivers. On the printed circuit board, this distance should remain constant to avoid discontinuities in differential impedance. Minor violations at connection points are allowable. TERMINATION Use a termination resistor which best matches the differential impedance or your transmission line. The resistor should be between 90 Ω and 130 Ω. Remember that the current mode outputs need the termination resistor to generate the differential voltage. LVDS will not work without resistor termination. Typically, connecting a single resistor across the pair at the receiver end will suffice. Surface mount 1% to 2% resistors are best. PCB stubs, component lead, and the distance from the termination to the receiver inputs should be minimized. The distance between the termination resistor and the receiver should be < 10 mm (12 mm MAX). POWER DECOUPLING RECOMMENDATIONS Bypass capacitors must be used on power pins. Use high frequency ceramic (surface mount is recommended) 0.1 µF and 0.001 µF capacitors in parallel at the power supply pin with the smallest value capacitor closest to the device supply pin. Additional scattered capacitors over the printed circuit board will improve decoupling. Multiple vias should be used to connect the decoupling capacitors to the power planes. A 10 µF (35 V) or greater solid tantalum capacitor should be connected at the power entry point on the printed circuit board between the supply and ground. PROBING LVDS TRANSMISSION LINES Always use high impedance ( > 100 kΩ), low capacitance ( < 2 pF) scope probes with a wide bandwidth (1 GHz) scope. Improper probing will give deceiving results. CABLES AND CONNECTORS, GENERAL COMMENTS When choosing cable and connectors for LVDS it is important to remember: Use controlled impedance media. The cables and connectors you use should have a matched differential impedance of about 100 Ω. They should not introduce major impedance discontinuities. Balanced cables (e.g. twisted pair) are usually better than unbalanced cables (ribbon cable, simple coax.) for noise reduction and signal quality. Balanced cables tend to generate less EMI due to field canceling effects and also tend to pick up electromagnetic radiation a common-mode (not differential mode) noise which is rejected by the receiver. PC BOARD CONSIDERATIONS Use at least 4 PCB layers (top to bottom); LVDS signals, ground, power, TTL signals. Isolate TTL signals from LVDS signals, otherwise the TTL may couple onto the LVDS lines. It is best to put TTL and LVDS signals on different layers which are isolated by a power/ground plane(s). Keep drivers and receivers as close to the (LVDS port side) connectors as possible. FAIL-SAFE FEATURE An LVDS receiver is a high gain, high speed device that amplifies a small differential signal (20 mV) to CMOS logic levels. Due to the high gain and tight threshold of the receiver, care should be taken to prevent noise from appearing as a valid signal. DIFFERENTIAL TRACES Use controlled impedance traces which match the differential impedance of your transmission medium (i.e. cable) and termination resistor. Run the differential pair trace lines as close together as possible as soon as they leave the IC (stubs should be < 10 mm long). This will help eliminate reflections and ensure noise is coupled as common-mode. In fact, we have seen that differential signals which are 1 mm apart radiate far less noise than traces 3 mm apart since www.national.com 8 External lower value pull up and pull down resistors (for a stronger bias) may be used to boost fail-safe in the presence of higher noise levels. The pull up and pull down resistors should be in the 5 kΩ to 15 kΩ range to minimize loading and waveform distortion to the driver. The common-mode bias point should be set to approximately 1.2 V (less than 1.75 V) to be compatible with the internal circuitry. (Continued) The receiver’s internal fail-safe circuitry is designed to source/sink a small amount of current, providing fail-safe protection (a stable known state of HIGH output voltage) for floating receiver inputs. The DS90LV049 has two receivers, and if an application requires a single receiver, the unused receiver inputs should be left OPEN. Do not tie unused receiver inputs to ground or any other voltages. The input is biased by internal high value pull up and pull down current sources to set the output to a HIGH state. This internal circuitry will guarantee a HIGH, stable output state for open inputs. For more information on failsfe biasing of LVDS interfaces please refer to AN-1194. Pin Descriptions Pin No. Name Description 10, 11 DIN 6, 7 DOUT+ Non-inverting driver output pins, LVDS levels. 5, 8 DOUT− Inverting driver output pins, LVDS levels. 2, 3 RIN+ Non-inverting receiver input pins, LVDS levels. There is a pull-up current source present. 1, 4 RIN- Inverting receiver input pins, LVDS levels. There is a pull-down current source present. 14, 15 ROUT 9, 16 EN, EN Driver input pins, LVCMOS levels. There is a pull-down current source present. Receiver output pins, LVCMOS levels. Enable and Disable pins. There are pull-down current sources present at both pins. 12 VDD Power supply pin. 13 GND Ground pin. Typical Performance Curves Differential Output Voltage vs Load Resistor Power Supply Current vs Frequency 20042021 20042019 9 www.national.com DS90LV049 Applications Information DS90LV049 3V LVDS Dual Line Driver with Dual Line Receiver Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead (0.100" Wide) Molded Thin Shrink Small Outline Package, JEDEC Order Number DS90LV049TMT Order Number DS90LV049TMTX (Tape and Reel) NS Package Number MTC16 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. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure 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 Americas Customer Support Center Email: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. 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