EL2004中文资料

EL2004 EL2004CNovember1993RevG Note All information contained in this data sheet has been carefully checked and is believed to be accurate as of the date of publication however this data sheet cannot be a‘‘controlled document’’ Current revisions if any to these specifications are maintained at the factory and are available upon your request We recommend checking the revision level before finalization of your design documentation Patent pending1989Elantec IncFeaturesSlew rate 2500V m sRise time 1nsBandwidth 350MHzELH0033 pin compatibleg5to g15V operation100mA output currentMIL-STD-883B Rev C devicesmanufactured in U S AApplicationsCoaxial cable driverFast op amp boosterFlash converter driverVideo line driverHigh-speed sample and holdPulse transformer driverA T E pin driverOrdering InformationPart No Temp Range Package OutlineEL2004CG b25 C to a85 C TO-8MDP0002EL2004G b55 C to a125 C TO-8MDP0002EL2004L b55 C to a125 C52-Pad LCC MDP0013EL2004L MIL b55 C to a125 C52-Pad LCC MDP00135962-89659is the SMD version of this deviceConnection DiagramCase is Electrically Isolated2004–1Top ViewGeneral DescriptionThe EL2004is a very high-speed FET input buffer line driverdesigned for unity gain applications at both high current(up to100mA)and at frequencies up to350MHz The2500V m s slewrate and wide bandwidth ensures the stability of the circuitwhen the EL2004is used inside op amp feedback loopsApplications for the EL2004include line drivers video bufferswideband instrumentation and high-speed drivers for inductiveand capacitive loads The performance of the EL2004makes itan ideal buffer for video applications including input buffers forflash A D converters and output buffers for video DACs Itsexcellent phase linearity is particularly advantageous in digitalsignal processing applicationsElantec facilities comply with MIL-I-45208A and are MIL-STD-1772certified Elantec’s Military devices comply withMIL-STD-883B Revision C and are manufactured in our rigidlycontrolled ultra-clean facilities in Milpitas California For ad-ditional information on Elantec’s Quality and Reliability Assur-ance Policy and procedures request brochure QRA-1Simplified Schematic2004–32T D i s 3 2 i n34T D i s 2 7 i n T D i s 3 4 i nAC Test Circuit2004–4Typical Performance CurvesDissipationMaximum Power TO-82004–5Gain vs Input VoltageOutput CurrentOutput Resistance vs2004–75Typical Performance Curves ContdTemperatureRise Time vs ResponseSmall Signal Pulse ResponseLarge Signal Pulse Frequency ResponseVoltageOffset Voltage vs Supply Warm-upCurrent During Normalized Input Bias Supply Voltage Supply Current vs Supply VoltageOutput Voltage vs 2004–86Applications InformationThe EL2004is one member of a family of high performance buffers manufactured by Elantec The2004is optimized for speed while others offer choices of input DC parameters or output drive or cost The following table illustrates those members available at the time of this printing Consult the factory for the latest capabilities in this developing lineElantec’s Buffer FamilySlewBandwidth Input Peak RisePart RateMHz Current I OUT TimeV m s(Warm)mA nsELH0002200506m A4007 ELH003315001002 5nA2502 9 EL200425003502 5nA2501 0 EL200515001400 1nA2502 5Recommended Layout PrecautionsThe very high-speed performance of the EL2004 can only be realized by taking certain precau-tions in circuit layout and power supply decou-pling Low inductance ceramic chip or disc power supply decoupling capacitors of0 1m F or more should be connected with the shortest practical lead lengths between the device supply leads and a ground plane In addition it can be helpful to parallel these with4 7m F electrolytics(Tanta-lum preferred) Failure to follow these precau-tions can result in oscillationCircuit OperationThe EL2004is effectively an ideal unity gain am-plifier with almost infinite input impedance and about6X output impedanceInput CharacteristicsThe input impedance of a junction FET is a strong function of temperature and input volt-age Nominal input resistance of EL2004is1012 at25 C junction but as I B doubles every11 C in the JFET the input resistance falls Duringwarm-up self-heating raises the junction temper-ature up to60 C or more(without heatsink)so operating I B will be much higher than the data sheet25 C specificationAnother factor which can increase bias current is input voltage If the input voltage is more than 20V below the positive supply the input current rises exponentially (See Curve )Input Bias Current vsTemperatureInput VoltageInput Bias Current vs2004–9 In applications such as sample and hold circuits where it is important to maintain low input bias current over input voltage range the EL2005 High Accuracy Fast Buffer is recommendedThe input capacitance of EL2004comprises the FET device gate-to-source capacitance(which isa function of input voltage)and stray capaci-tance to the case Effective input capacitance can be minimized by connecting the case to the out-put since it is electrically isolated Or for reduced radiation the case may be grounded The AC characteristics specified in this data sheet were obtained with the case floatingOffset Voltage AdjustmentThe EL2004’s offset voltages have been actively laser trimmed at g15V supplies to meet specified limits when the offset adjust pin is shorted to the offset preset pin If external offset null is re-quired the offset adjust pin should be connected to a200X trim pot connected to the negative sup-ply7Circuit Operation ContdOffset Zero Adjust2004–10Capacitive LoadingThe EL2004is designed to drive capacitive loadsup to several thousand picofarads without oscil-lation However peak current resulting fromcharging currents on fast edges should be limitedbelow the absolute maximum peak current ratingof250mA In some cases it may be necessary toemploy one of the current limit schemes shownbelowShort Circuit ProtectionDynamic response of the EL2004was preservedby excluding current limit circuits which are notneeded in most applications However in situa-tions where operating conditions are not con-trolled short circuit protection can be added byinserting resistors between the output device col-lectors and supplies as illustratedUsing ResistorCurrent Limiting2004–11Suitable resistor values can be calculated as fol-lowsR SC eV aI SCeV bI SCwhere I SC s100mA for EL2004Current LimitingUsing Current Sources2004–12The inclusion of limiting resistors in the collec-tors of the output devices will reduce the outputvoltage swing and speed Decoupling V C a andV C b pins with capacitors to ground will retainfull output swing for transient pulsesAn alternate active current limit technique thatretains full DC output swing is shown aboveHere the current sources are saturated duringnormal operation thus applying full supply volt-age to the V C pins Under fault conditions thevoltage decreases as the current source reaches itslimitR LIM eV BEI SCe0 6V100mAe6XPower SuppliesThe EL2004has been characterized for both g15and g5V dual supply operation but other combi-nations can also be useful For example in manyvideo applications it is only necessary for the out-put to swing g2V or less but speed and distor-tion are important In this situation the inputstage can be operated at the full g15V supplywhile the output collectors are returned to g5VThe speed and distortion will be almost as goodas if the whole circuit was operating at g15Vbut the dissipation is substantially reduced andhigher load currents can be safely accommodat-ed8Circuit Operation ContdIncreasing Operating Voltageand Reducing Thermal TailWhen driving heavy loads the changing dissipa-tion in the output transistors can sometimescause temperature gradients in the circuit whichcause a shift in offset voltage and the phenome-non known as‘‘thermal tail’’ Bootstrapping theoutput as illustrated substantially reduces thepower in the output transistors and mitigates theeffectHigh Voltage Inputs can be Accommodatedwith Bootstrapped Supplies2004–13HardwareIn order to utilize the full drive capabilities of theEL2004 it should be mounted with a heatsinkparticularly for extended temperature operationSuitable heatsinks include Thermalloy2240A(33 C W) Wakefield215CB(30 C W)andIERC-UP-TO-848CB(15 C W)The case is isolated from the circuit and may beconnected to system chassis Sockets are not rec-ommended as they add substantial inductanceand capacitance which impair the performance ofthe device However for test purposes they areunavoidable and precautions such as shielding in-put from output are suggestedGeneral Application SuggestionsVideo DAC BufferMany of the available video D to A convertersare unable to directly drive50X or75X cablesThe EL2004’s excellent phase linearity at videofrequencies make it an ideal solution In criticalapplications or where line termination is not con-trolled a matching pad should be used as shownThe capacitor should be adjusted for optimumpulse response If properly layed out this circuitwill not overshootVideo DAC Buffer2004–14Impedance MatchingThe EL2004provides power gain and isolationbetween source and load when used as an activetap or impedance matching device as illustratedhere In this example there is no output match-ing pad between the2004and the75X line Suchmatching is not needed when the distant end ofthe cable is properly terminated as there is noreflected signal to worry about and the2004iso-lates the source This technique allows the fulloutput voltage of the EL2004to be applied to theloadImpedance Converter2004–159General Application Suggestions ContdInverting Amplifier for 20MHz Flash Converter2004–16Boosting the OutputUnlike most integrated cicuits two or more EL2004’s can be paralleled for increased output drive This capability results from the finite out-put resistance and low output mismatch of theEL2004 For example a 50X cable driver with g 10V capability can be made by using two EL2004’s A short-circuit protected version is shown below50X Cable Driver with Short Circuit ProtectionNPN e 2N6551(PNP e 2N6554or equivalent 2W devices2004–1710Burn-In Circuit2004–18Pin numbers are for TO-8packageLCC uses the same schematic11EL2004MacromodelConnections inputl V al l Vc al l l V bl l l l Vc bl l l l l outputl l l l l lsubckt M2004512110911Modelsmodel qn npn(is e5e b14bf e150vaf e100rc e1rb e5re e1ikf e200mAa cje e5pF cjc e5pF mje e 42mjc e 23tf e 3nS tr e200nS br e5vtf e0)model qp pnp(is e5e b14bf e150vaf e100rc e2rb e3re e1ikf e100mAa cje e5 7pF cjc e4pF tf e 3nS mje e 32mjc e 43tr e170nS br e5vtf e0)model qf njf(vto eb3V beta e4 0e b3cgd e4pF cgs e10pF lambda e671 0e b6) Resistorsr1202158 33r2271058 33r322112r411232Transistorsj112520qfj4241026qfq2212125qnq3242425qpq512122qnq692423qpq7262627qnends12TAB WIDET Dis38inEL2004Macromodel Contd2004–1913KNALB14KNALB15E L 2004 N o v e m b e r 1993R e v GGeneral DisclaimerSpecifications contained in this data sheet are in effect as of the publication date shown Elantec Inc reserves the right to make changes in the circuitry or specifications contained herein at any time without notice Elantec Inc assumes no responsibility for the use of any circuits described herein and makes no representations that they are free from patent infringementElantec Inc 1996Tarob Court Milpitas CA 95035Telephone (408)945-1323(800)333-6314Fax (408)945-9305European Office 44-71-482-4596WARNING Life Support PolicyElantec Inc products are not authorized for and should not be used within Life Support Systems without the specific written consent of Elantec Inc Life Support systems are equipment in-tended to support or sustain life and whose failure to perform when properly used in accordance with instructions provided can be reasonably expected to result in significant personal injury or death Users contemplating application of Elantec Inc products in Life Support Systems are requested to contact Elantec Inc factory headquarters to establish suitable terms conditions for these applications Elantec Inc ’s warranty is limited to replace-ment of defective components and does not cover injury to per-sons or property or other consequential damagesPrinted in U S A16。