LT6600-20ABSOLUTE AXIU RATIGS(Note 1)WUPACKAGE/ORDER IFORATIOTOP VIEWIN–1VOCM2V+3OUT+48765IN+VMIDV–OUT–UTotal Supply Voltage................................................11VOperating Temperature Range (Note 6)...–40°C to 85°CSpecified Temperature Range (Note 7)....–40°C to 85°CJunction Temperature...........................................150°CStorage Temperature Range.................–65°C to 150°CLead Temperature (Soldering, 10 sec)..................300°CThe q denotes specifications that apply over the full operating temperaturerange, otherwise specifications are at TA = 25°C. Unless otherwise specified VS = 5V (V+ = 5V, V– = 0V), RIN = 402Ω, and RLOAD = 1k.PARAMETERFilter Gain, VS = 3VCONDITIONSVIN = 2VP-P, fIN = DC to 260kHzVIN = 2VP-P, fIN = 2MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 10MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 16MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 20MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 60MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 100MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = DC to 260kHzVIN = 2VP-P, fIN = 2MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 10MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 16MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 20MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 60MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = 100MHz (Gain Relative to 260kHz)VIN = 2VP-P, fIN = DC to 260kHzVIN = 2VP-P, fIN = DC to 260kHz, VS = 3VVIN = 2VP-P, fIN = DC to 260kHz, VS = 5VVIN = 2VP-P, fIN = DC to 260kHz, VS = ±5VfIN = 250kHz, VIN = 2VP-PNoise BW = 10kHz to 20MHz2.5MHz, 2VP-P, RL = 800Ω2nd Harmonic3rd Harmonic20MHz, 2VP-P, RL = 800Ω2nd Harmonic3rd HarmonicMeasured Between Pins 4 and 5VS = 5VVS = 3VAverage of Pin 1 and Pin 8MIN–0.4–0.1–0.2–0.1–0.8TYP0.100.10.50–33–50000.10.4–0.4–33–50–0.112.112.011.97801188388634.7.50–50MAX0.50.10.51.91–280.50.10.41.60.6–280.412.612.512.4UNITSdBdBdBdBdBdBdBdBdBdBdBdBdBdBdBdBdBdBppm/CµVRMSdBcdBcdBcdBcVP-P DIFFVP-P DIFFµAELECTRICAL CHARACTERISTICSFilter Gain, VS = 5VFilter Gain, VS = ±5VFilter Gain, RIN = 100ΩFilter Gain Temperature Coefficient (Note 2)NoiseDistortion (Note 4)Differential Output SwingInput Bias Current2
UWWWORDER PARTNUMBERLT6600CS8-20LT6600IS8-20S8 PART MARKING660020600I20S8 PACKAGE8-LEAD PLASTIC SOTJMAX = 150°C, θJA = 100°C/WConsult LTC Marketing for parts specified with wider operating temperature ranges.qqqqqqqqqqqq–0.5–0.1–0.2–0.3–1.3–0.611.611.511.4qqq3.803.75–9566002fLT6600-20The q denotes specifications that apply over the full operating temperaturerange, otherwise specifications are at TA = 25°C. Unless otherwise specified VS = 5V (V+ = 5V, V– = 0V), RIN = 402Ω, and RLOAD = 1k.PARAMETERInput Referred Differential OffsetCONDITIONSRIN = 402ΩRIN = 100ΩDifferential Offset DriftInput Common Mode Voltage (Note 3)MINVS = 3VVS = 5VVS = ±5VVS = 3VVS = 5VVS = ±5VVS = 3VVS = 5VVS = ±5VVS = 3VVS = 5VVS = ±5VVS = 3VVS = 5VVS = ±5VVS = 5VS = 3VOCM = VMID= VS/2VS = 5VVS = 3VVS = 3V, VS = 5VS = 3V, VS = 5VS = ±5VqqqqqqqqqqqqqqqqqqqqqELECTRICAL CHARACTERISTICSTYP5101055510MAX2530351517201.53.01.01.53.02.0404035 2.557.65Differential Input = 500mVP-P,RIN = 100ΩDifferential Input = 2VP-P,Pin 7 at Mid-SupplyCommon Mode Voltage at Pin 2Output Common Mode Voltage (Note 5)Output Common Mode Offset(with Respect to Pin 2)Common Mode Rejection RatioVoltage at VMID (Pin 7)VMID Input ResistanceVOCM Bias CurrentPower Supply Current0.00.0–2.51.01.5–1.0–35–40–552.4.35–15–10 5 0–566 2.511.55.7–3–342465356UNITSmVmVmVmVmVmVµV/°CVVVVVVmVmVmVdBVVkΩµAµAmAmAmANote 1: Absolute Maximum Ratings are those values beyond which the lifeof a device may be impaired.Note 2: This is the temperature coefficient of the internal feedbackresistors assuming a temperature independent external resistor (RIN).Note 3: The input common mode voltage is the average of the voltagesapplied to the external resistors (RIN). Specification guaranteed forRIN ≥ 100Ω.Note 4: Distortion is measured differentially using a differential stimulus,The input common mode voltage, the voltage at Pin 2, and the voltage atPin 7 are equal to one half of the total power supply voltage.Note 5: Output common mode voltage is the average of the voltages atPins 4 and 5. The output common mode voltage is equal to the voltageapplied to Pin 2.Note 6: The LT6600C-20 is guaranteed functional over the operatingtemperature range –40°C to 85°C.Note 7: The LT6600C-20 is guaranteed to meet 0°C to 70°C specificationsand is designed, characterized and expected to meet the extendedtemperature limits, but is not tested at –40°C and 85°C. The LT6600I-20is guaranteed to meet specified performance from –40°C to 85°C.66002f
3
LT6600-20TYPICAL PERFOR A CE CHARACTERISTICS Amplitude Response100–10–20GAIN (dB)–40–50–60–70–80VS = 5VGAIN = 1TA = 25°C110FREQUENCY (MHz)10066002 G01GAIN (dB)GAIN (dB)–30–900.1Passband Gain and Group Delay1412108GAINVS = 5VGAIN = 4TA = 25°C5045OUTPUT IMPEDANCE (Ω)GAIN (dB)20–2–4–60.530252015105CMRR (dB)GROUPDELAY6.518.524.512.5FREQUENCY (MHz)Power Supply Rejection Ratio100908070V+ TO DIFFOUTVS = 3VTA = 25°CDISTORTION (dB)DISTORTION (dB)PSRR (dB)60504030201000.0010.010.11FREQUENCY (MHz)4
UW66002 G04Passband Gain and Phase20–2–4–6–8–10–12–14–16–180.56.518.524.512.5FREQUENCY (MHz)PHASEGAINVS = 5VGAIN = 1TA = 25°C95505–4020–2–4Passband Gain and Group DelayGAINVS = 5VGAIN = 1TA = 25°C504035GROUPDELAY302520151056.518.524.512.5FREQUENCY (MHz)030.566002 G03GROUP DELAY (ns)PHASE (DEG)–85–130–175–6–8–10–12–14–16–180.5–220–265–310–35530.566002 G02Output Impedance100VS = 5VGAIN = 1TA = 25°C807570656055504035Common Mode Rejection RatioINPUT = 1VP-PVS = 5VGAIN = 1TA = 25°C4035GROUP DELAY (ns)101030.50.10.130110FREQUENCY (MHz)10066002 G050.1110FREQUENCY (MHz)10066002 G06Distortion vs Frequency–40–50–60–70–80–90–100DIFFERENTIAL INPUT, 2ND HARMONICDIFFERENTIAL INPUT, 3RD HARMONICSINGLE-ENDED INPUT, 2ND HARMONICSINGLE-ENDED INPUT, 3RD HARMONIC–40–50–60–70–80–90–100Distortion vs Signal Level,VS = 3V3RD HARMONICVS = 3V10MHz INPUTRL = 800Ω ATEACH OUTPUTGAIN = 12NDTA = 25°CHARMONIC10MHz INPUT3RDHARMONIC1MHz INPUT2ND HARMONIC1MHz INPUTVIN = 2VP-PVS = 3VRL = 800Ω ATEACH OUTPUTGAIN = 1TA = 25°C0.1110FREQUENCY (MHz)10066002 G081010066002 G070123INPUT LEVEL (VP-P)4566002 G0966002fLT6600-20TYPICAL PERFOR A CE CHARACTERISTICS Distortion vs Signal Level,VS = ±5V–40–50DISTORTION (dB)–60–70–80–90–1002ND HARMONIC,10MHz INPUT3RD HARMONIC,10MHz INPUT2ND HARMONIC,1MHz INPUT3RD HARMONIC,1MHz INPUT–40DISTORTION COMPONENT (dB)–60–70–80–90DISTORTION COMPONENT (dB)VS = ±5VRL = 800Ω ATEACH OUTPUTGAIN = 1TA = 25°C0123INPUT LEVEL (VP-P)4566002 G10DISTORTION COMPONENT (dB)Total Supply Currentvs Total Supply Voltage60TA = 85°CTA = 25°CTA = –40°CTOTAL SUPPLY CURRENT (mA)50403020100012345678TOTAL SUPPLY VOLTAGE (V)UWDistortionvs Input Common Mode Level2ND HARMONIC,VS = 3V3RD HARMONIC,VS = 3V2ND HARMONIC,VS = 5V3RD HARMONIC,VS = 5V2VP-P 1MHz INPUTRL = 800Ω ATEACH OUTPUTGAIN = 1TA = 25°C–40–50–60–70–80–90Distortionvs Input Common Mode Level2ND HARMONIC,VS = 3V3RD HARMONIC,VS = 3V2ND HARMONIC,VS = 5V3RD HARMONIC,VS = 5V–50–100–3–2–10123INPUT COMMON MODE VOTLAGE RELATIVE TO PIN 7 (V)66002 G11–100500mVP-P 1MHz INPUT, GAIN = 4,RL = 800Ω AT EACH OUTPUT–3–2–10123INPUT COMMON MODE VOTLAGE RELATIVE TO PIN 7 (V)66002 G12Distortionvs Output Common Mode–40–50–60–70–80–90–100–1102VP-P 1MHz INPUT, GAIN = 1,RL = 800Ω AT EACH OUTPUT–2–1.5–1–0.500.511.5VOLTAGE PIN 2 TO PIN 7 (V)22ND HARMONIC,VS = 3V3RD HARMONIC,VS = 3V2ND HARMONIC,VS = 5V3RD HARMONIC,VS = 5V2ND HARMONIC,VS = ±5V3RD HARMONIC,VS = ±5V66002 G13Transient Response, Gain = 1VOUT+50mV/DIVDIFFERENTIALINPUT200mV/DIV100ns/DIV66002 G1591066002 G1466002f5
LT6600-20PI FU CTIO SIN– and IN+ (Pins 1, 8): Input Pins. Signals can be appliedto either or both input pins through identical externalresistors, RIN. The DC gain from differential inputs to thedifferential outputs is 402Ω/RIN.VOCM (Pin 2): Is the DC Common Mode Reference Voltagefor the 2nd Filter Stage. Its value programs the commonmode voltage of the differential output of the filter. Pin 2 isa high impedance input, which can be driven from anexternal voltage reference, or Pin 2 can be tied to Pin 7 onthe PC board. Pin 2 should be bypassed with a 0.01µFceramic capacitor unless it is connected to a ground plane.V+ and V– (Pins 3, 6): Power Supply Pins. For a single3.3V or 5V supply (Pin 6 grounded) a quality 0.1µFceramic bypass capacitor is required from the positivesupply pin (Pin 3) to the negative supply pin (Pin 6). Thebypass should be as close as possible to the IC. For dualsupply applications, bypass Pin 3 to ground and Pin 6 toground with a quality 0.1µF ceramic capacitor.OUT+ and OUT– (Pins 4, 5): Output Pins. Pins 4 and 5 arethe filter differential outputs. Each pin can drive a 100Ωand/or 50pF load.VMID (Pin 7): The VMID pin is internally biased at mid-supply, see block diagram. For single supply operation,the VMID pin should be bypassed with a quality 0.01µFceramic capacitor to Pin 6. For dual supply operation, Pin7 can be bypassed or connected to a high quality DCground. A ground plane should be used. A poor groundwill increase noise and distortion. Pin 7 sets the outputcommon mode voltage of the 1st stage of the filter. It hasa 5.5kΩ impedance, and it can be overridden with anexternal low impedance voltage source.BLOCK DIAGRA VIN+RIN8IN+VMID7V+11k402Ω11k200ΩV–OP AMPV–6OUT–5VIN–6
WUUUPROPRIETARYLOWPASSFILTER STAGE+VOCM–+200Ω+–VOCM–200Ω–+200Ω402Ω1RININ–2VOCM3V+466002 BDOUT+66002fLT6600-20APPLICATIO S I FOR ATIOInterfacing to the LT6600-20The LT6600-20 requires two equal external resistors, RIN,to set the differential gain to 402Ω/RIN. The inputs to thefilter are the voltages VIN+ and VIN– presented to theseexternal components, Figure 1. The difference betweenVIN+ and VIN– is the differential input voltage. The averageof VIN+ and VIN– is the common mode input voltage.Similarly, the voltages VOUT+ and VOUT– appearing at Pins4 and 5 of the LT6600-20 are the filter outputs. Thedifference between VOUT+ and VOUT– is the differentialoutput voltage. The average of VOUT+ and VOUT– is thecommon mode output voltage.Figure 1 illustrates the LT6600-20 operating with a single3.3V supply and unity passband gain; the input signal isDC coupled. The common mode input voltage is 0.5V, andthe differential input voltage is 2VP-P. The common modeV3210VIN+t0.01µF+VIN–VIN402Ω402ΩVIN–V0.1µF210–1VIN+0.1µFtVIN+V3210500mVP-P (DIFF)VIN+VIN–t0.01µFVIN+–VINUoutput voltage is 1.65V, and the differential output voltageis 2VP-P for frequencies below 20MHz. The common modeoutput voltage is determined by the voltage at pin 2. Sincepin 2 is shorted to pin 7, the output common mode is themid-supply voltage. In addition, the common mode inputvoltage can be equal to the mid-supply voltage of Pin 7(see the Distortion vs Input Common Mode Level graphsin the Typical Performance Characteristics).Figure 2 shows how to AC couple signals into theLT6600-20. In this instance, the input is a single-endedsignal. AC coupling allows the processing of single-endedor differential signals with arbitrary common mode levels.The 0.1µF coupling capacitor and the 402Ω gain settingresistor form a high pass filter, attenuating signals below4kHz. Larger values of coupling capacitors will propor-tionally reduce this highpass 3dB frequency.3.3V0.1µF17283V3WUU–+6LT6600-20+4VOUT+210VOUT+VOUT–t66002 F01–5VOUT–Figure 13.3V0.1µF402Ω170.01µF402Ω283V3VOUT+–+6LT6600-20+4210VOUT+VOUT––5VOUT–66002 F02Figure 262pF5V30.1µF32VOUT–10VOUT–V100Ω1728–+6LT6600-20+4VOUT+VOUT+–5100Ω+–2V66002 F03t62pFFigure 366002f7
LT6600-20APPLICATIOS IFORATIOIn Figure 3 the LT6600-20 is providing 12dB of gain. Thegain resistor has an optional 62pF in parallel to improvethe passband flatness near 20MHz. The common modeoutput voltage is set to 2V.Use Figure 4 to determine the interface between theLT6600-20 and a current output DAC. The gain, or “trans-impedance,” is defined as A = VOUT/IIN. To compute thetransimpedance, use the following equation:A=402•R1(Ω)12R+R()By setting R1 + R2 = 402Ω, the gain equation reduces toA = R1(Ω).The voltage at the pins of the DAC is determined by R1,R2, the voltage on Pin 7 and the DAC output current.Consider Figure 4 with R1 = 49.9Ω and R2 = 348Ω. Thevoltage at Pin 7 is 1.65V. The voltage at the DAC pins isgiven by:R1R1•R2VDAC=VPIN7•+IIN•R1+R2+402R1+R2=26mV+IIN•48.3ΩIIN is IIN+ or IIN–. The transimpedance in this example is50.4Ω.Evaluating the LT6600-20The low impedance levels and high frequency operation ofthe LT6600-20 require some attention to the matchingnetworks between the LT6600-20 and other devices. Theprevious examples assume an ideal (0Ω) source imped-ance and a large (1kΩ) load resistance. Among practicalCURRENTOUTPUTDACIIN–3.3V0.1µFR2317R1IIN+R1–++VOUT0.01µF2LT6600-208R2–5VOUT–66002 F04Figure 48
Uexamples where impedance must be considered is theevaluation of the LT6600-20 with a network analyzer.Figure 5 is a laboratory setup that can be used to charac-terize the LT6600-20 using single-ended instruments with50Ω source impedance and 50Ω input impedance. For aunity gain configuration the LT6600-20 requires a 402Ωsource resistance yet the network analyzer output iscalibrated for a 50Ω load resistance. The 1:1 transformer,53.6Ω and 388Ω resistors satisfy the two constraintsabove. The transformer converts the single-ended sourceinto a differential stimulus. Similarly, the output of theLT6600-20 will have lower distortion with larger loadresistance yet the analyzer input is typically 50Ω. The 4:1turns (16:1 impedance) transformer and the two 402Ωresistors of Figure 5, present the output of the LT6600-20with a 1600Ω differential load, or the equivalent of 800Ωto ground at each output. The impedance seen by thenetwork analyzer input is still 50Ω, reducing reflections inthe cabling between the transformer and analyzer input.Differential and Common Mode Voltage RangesThe differential amplifiers inside the LT6600-20 containcircuitry to limit the maximum peak-to-peak differentialvoltage through the filter. This limiting function preventsexcessive power dissipation in the internal circuitryand provides output short-circuit protection. The limitingfunction begins to take effect at output signal levels above2VP-P and it becomes noticeable above 3.5VP-P. This isillustrated in Figure 6; the LT6600-20 was configured withunity passband gain and the input of the filter was drivenwith a 1MHz signal. Because this voltage limiting takesplace well before the output stage of the filter reaches the2.5V0.1µFNETWORKANALYZERSOURCE50Ω+WUUCOILCRAFTTTWB-10101:1388Ω1753.6Ω388Ω283–+6LT6600-20+4COILCRAFTTTWB-16A4:1402ΩNETWORKANALYZERINPUT50Ω–02Ω66002 F050.1µF–2.5VFigure 566002fLT6600-20APPLICATIOS IFORATIO200OUTPUT LEVEL (dBV)1dB PASSBAND GAINCOMPRESSION POINTS1MHz 25°C1MHz 85°C–20–40–60–80–1003RD HARMONIC85°C3RD HARMONIC25°C2ND HARMONIC25°C2ND HARMONIC85°C0143521MHz INPUT LEVEL (VP-P)67–12066002 F06Figure 6. Output Level vs Input Level,Differential 1MHz Input, Gain = 1supply rails, the input/output behavior of the IC shown inFigure 6 is relatively independent of the power supplyvoltage.The two amplifiers inside the LT6600-20 have indepen-dent control of their output common mode voltage (seethe “block diagram” section). The following guidelines willoptimize the performance of the filter.Pin 7 must be bypassed to an AC ground with a 0.01µF orlarger capacitor. Pin 7 can be driven from a low impedancesource, provided it remains at least 1.5V above V– and atleast 1.5V below V+. An internal resistor divider sets thevoltage of Pin 7. While the internal 11k resistors are wellmatched, their absolute value can vary by ±20%. Thisshould be taken into consideration when connecting anexternal resistor network to alter the voltage of Pin 7.Pin 2 can be shorted to Pin 7 for simplicity. If a differentcommon mode output voltage is required, connect Pin 2to a voltage source or resistor network. For 3V and 3.3Vsupplies the voltage at Pin 2 must be less than or equal tothe mid supply level. For example, voltage (Pin 2) ≤ 1.65Von a single 3.3V supply. For power supply voltages higherthan 3.3V the voltage at Pin 2 should be within the voltageof Pin 7 – 1V to the voltage of Pin 7 + 2V. Pin 2 is a highimpedance input.UThe LT6600-20 was designed to process a variety of inputsignals including signals centered around the mid-supplyvoltage and signals that swing between ground and apositive voltage in a single supply system (Figure 1). Therange of allowable input common mode voltage (theaverage of VIN+ and VIN– in Figure 1) is determined bythe power supply level and gain setting (see Distortion vsInput Common Mode Level in the Typical PerformanceCharacteristics).Common Mode DC CurrentsIn applications like Figure 1 and Figure 3 where theLT6600-20 not only provides lowpass filtering but alsolevel shifts the common mode voltage of the input signal,DC currents will be generated through the DC path be-tween input and output terminals. Minimize these currentsto decrease power dissipation and distortion.Consider the application in Figure 3. Pin 7 sets the outputcommon mode voltage of the 1st differential amplifierinside the LT6600-20 (see the “Block Diagram” section) at2.5V. Since the input common mode voltage is near 0V,there will be approximately a total of 2.5V drop across theseries combination of the internal 402Ω feedback resistorand the external 100Ω input resistor. The resulting 5mAcommon mode DC current in each input path, must beabsorbed by the sources VIN+ and VIN–. Pin 2 sets thecommon mode output voltage of the 2nd differentialamplifier inside the LT6600-20, and therefore sets thecommon mode output voltage of the filter. Since, in theexample of Figure 3, Pin 2 differs from Pin 7 by 0.5V, anadditional 2.5mA (1.25mA per side) of DC current will flowin the resistors coupling the 1st differential amplifieroutput stage to filter output. Thus, a total of 12.5mA isused to translate the common mode voltages.A simple modification to Figure 3 will reduce the DCcommon mode currents by 36%. If Pin 7 is shorted toPin 2 the common mode output voltage of both op ampstages will be 2V and the resulting DC current will be 8mA.Of course, by AC coupling the inputs of Figure 3, thecommon mode DC current can be reduced to 2.5mA.66002fWUU9
LT6600-20APPLICATIOS IFORATIONoiseThe noise performance of the LT6600-20 can be evaluatedwith the circuit of Figure 7.Given the low noise output of the LT6600-20 and the 6dBattenuation of the transformer coupling network, it isnecessary to measure the noise floor of the spectrumanalyzer and subtract the instrument noise from the filternoise measurement.Example: With the IC removed and the 25Ω resistorsgrounded, Figure 7, measure the total integrated noise(eS) of the spectrum analyzer from 10kHz to 20MHz. Withthe IC inserted, the signal source (VIN) disconnected, andthe input resistors grounded, measure the total integratednoise out of the filter (eO). With the signal source con-nected, set the frequency to 1MHz and adjust the ampli-tude until VIN measures 100mVP-P. Measure the outputamplitude, VOUT, and compute the passband gainA = VOUT/VIN. Now compute the input referred integratednoise (eIN) as:NOISE SPECTRAL DENSITY (nVRMS/√Hz)(eO)2–(eS)2eIN=ATable 1 lists the typical input referred integrated noise forvarious values of RIN.Figure 8 is plot of the noise spectral density as a functionof frequency for an LT6600-20 with RIN = 402Ω using thefixture of Figure 7 (the instrument noise has been sub-tracted from the results).Table 1. Noise PerformancePASSBANDGAIN (V/V)421INPUT REFERREDINTEGRATED NOISE10kHz TO 20MHz42µVRMS67µVRMS118µVRMSINPUT REFERREDNOISE dBm/Hz–148–143–139RIN100Ω200Ω402ΩThe noise at each output is comprised of a differentialcomponent and a common mode component. Using atransformer or combiner to convert the differential outputsto single-ended signal rejects the common mode noise andgives a true measure of the S/N achievable in the system.Conversely, if each output is measured individually and the10
U2.5V0.1µFVINRIN3COILCRAFTTTWB-101025Ω1:1SPECTRUMANALYZERINPUT50Ω25Ω66002 F07WUU1728–++LT6600-20–RIN50.1µF–2.5VFigure 750VS = 5V25040200INTEGRATED NOISE (µVRMS)30SPECTRAL DENSITY2015010010INTEGRATED5000.1110010066002 F08FREQUENCY (MHz)Figure 8. Input Referred Noise, Gain = 1noise power added together, the resulting calculated noiselevel will be higher than the true differential noise.Power DissipationThe LT6600-20 amplifiers combine high speed with large-signal currents in a small package. There is a need toensure that the die junction temperature does not exceed150°C. The LT6600-20 package has Pin 6 fused to the leadframe to enhance thermal conduction when connecting toa ground plane or a large metal trace. Metal trace andplated through-holes can be used to spread the heatgenerated by the device to the backside of the PC board.For example, on a 3/32\" FR-4 board with 2oz copper, a totalof 660 square millimeters connected to Pin 6 of theLT6600-20 (330 square millimeters on each side of the PCboard) will result in a thermal resistance, θJA, of about85°C/W. Without the extra metal trace connected to the V–pin to provide a heat sink, the thermal resistance will bearound 105°C/W. Table 2 can be used as a guide whenconsidering thermal resistance.66002fLT6600-20APPLICATIOS IFORATIO COPPER AREATOPSIDE(mm2)110033035350BACKSIDE(mm2)11003303500BOARD AREA(mm2)25002500250025002500Table 2. LT6600-20 SO-8 Package Thermal ResistanceTHERMAL RESISTANCE(JUNCTION-TO-AMBIENT)65°C/W85°C/W95°C/W100°C/W105°C/WJunction temperature, TJ, is calculated from the ambienttemperature, TA, and power dissipation, PD. The powerdissipation is the product of supply voltage, VS, andsupply current, IS. Therefore, the junction temperature isgiven by:TJ = TA + (PD • θJA) = TA + (VS • IS • θJA)where the supply current, IS, is a function of signal level,load impedance, temperature and common modevoltages.PACKAGE DESCRIPTIOS8 Package8-Lead Plastic Small Outline (Narrow .150 Inch)(Reference LTC DWG # 05-08-1610).045 ±.005 .050 BSC8.1 – .197(4.801 – 5.004)NOTE 3765.245MIN.030 ±.005 TYPRECOMMENDED SOLDER PAD LAYOUT.010 – .020× 45°(0.2 – 0.508).008 – .010(0.203 – 0.2).016 – .050(0.406 – 1.270)NOTE:1. DIMENSIONS IN 0°– 8° TYPINCHES(MILLIMETERS)2. DRAWING NOT TO SCALE3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006\" (0.15mm)Information furnished by Linear Technology Corporation is believed to be accurate and reliable.However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.UFor a given supply voltage, the worst-case power dissi-pation occurs when the differential input signal is maxi-mum, the common mode currents are maximum (seeApplications Information regarding common mode DCcurrents), the load impedance is small and the ambienttemperature is maximum. To compute the junction tem-perature, measure the supply current under these worst-case conditions, estimate the thermal resistance fromTable 2, then apply the equation for TJ. For example, usingthe circuit in Figure 3 with a DC differential input voltageof 250mV, a differential output voltage of 1V, no loadresistance and an ambient temperature of 85°C, thesupply current (current into Pin 3) measures 55.5mA.Assuming a PC board layout with a 35mm2 copper trace,the θJA is 100°C/W. The resulting junction temperature is:TJ = TA + (PD • θJA) = 85 + (5 • 0.0555 • 100) = 113°CWhen using higher supply voltages or when driving smallimpedances, more copper may be necessary to keep TJbelow 150°C..160 ±.005.228 – .244(5.791 – 6.197).150 – .157(3.810 – 3.988)NOTE 31234.053 – .069(1.346 – 1.752).004 – .010(0.101 – 0.2).014 – .019(0.355 – 0.483)TYP.050(1.270)BSCSO8 0303WUUU66002f11
LT6600-20TYPICAL APPLICATIOAmplitude Response100–10–20GAIN (dB)–30–40–50–60–70–80VS = ±2.5VGAIN = 1C = 39pFR = 200ΩTA = 25°C101FREQUENCY (MHz)10066002 TA04–900.1RELATED PARTSPART NUMBERLTC®1565-31LTC1566-1LT1567LT1568LT6600-2.5LT6600-10DESCRIPTION650kHz Linear Phase Lowpass FilterLow Noise, 2.3MHz Lowpass FilterVery Low Noise, High Frequency Filter Building BlockVery Low Noise, 4th Order Building BlockVery Low Noise Differential Amplifier and 2.5MHzLowpass FilterVery Low Noise Differential Amplifier and 10MHzLowpass FilterCOMMENTSContinuous Time, SO8 Package, Fully DifferentialContinuous Time, SO8 Package1.4nV/√Hz Op Amp, MSOP Package, Fully DifferentialLowpass and Bandpass Filter Designs Up to 10MHz,Differential Outputs86dB S/N with 3V Supply, SO-882dB S/N with 3V Supply, SO-812
Linear Technology Corporation1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507 q www.linear.comUA 5th Order, 20MHz Lowpass FilterV+0.1µFVIN–RRC17283–+6+–4VOUT+VOUT–LT6600-2050.1µFVIN+C =RR12π • R • 20MHzGAIN =402Ω, MAXIMUM GAIN = 4V–2R66002 TA02aTransient Response, Gain = 1VOUT+50mV/DIVDIFFERENTIALINPUT200mV/DIV100ns/DIV66002 TA0366002f LT/TP 0503 1K • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 2003
因篇幅问题不能全部显示，请点此查看更多更全内容
Copyright © 2019- oldu.cn 版权所有 浙ICP备2024123271号-1
违法及侵权请联系：TEL:199 1889 7713 E-MAIL:2724546146@qq.com
本站由北京市万商天勤律师事务所王兴未律师提供法律服务