常用芯片资料——1407.docx

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1、Single Supply feiHcrRail Low Power FEHrput Op AmpAD822FEATURESTrue Single Supply OperationOutput Swings Rail to RailInput Voltage Range Extends below GroundSingle Supply Capability from 3 V to 36 VDual Supply Capability from L 5 V to 18 VHigh Load DriveCapacitive Load Drive of 350 pE G = +1Mini mu m

2、 Output Current of 15 mAExcellent AC Performance for Low Power800 mA Max Quiescent Current per AmplifierUnity Gain Bandwidth: L 8 M HzSlew Rate of 3. 0 V/msGood DC Performance800 mV Max Input Offset Voltage2 mV/ C Typ Offset Voltage Drift25 pA Max Input Bias CurrentLow Noise13 nV/VHz 10 kHzNo Phase

3、InversionAPPLICATIONSBatt er 厂 Powe red Precision InstrumentationPhotodiode PreampsActive Filters12- to 14-BitData Acquisition SystemsM e dical Instru m e ntationLow Power References and RegulatorsPRODUCT DESCRIPTIONThe A D822 is a dual precision, low power FET input op am p that can operate from a

4、single supply of 3. 0 V to 36 V, or dual supplies of L5 V to 18 V. It has true single supply capabilityCONNECTION DIAGRAM8-Lead Plastic DI P, MS OP, and SOICOUT118V+-INI27OUT2+IN136-IN2V-4AD8225+IN2with an input voltage range extending below the negative raU, allowing the AD822 to accommodate input

5、signals below ground in the single supply mode. Output voltage swing extends to within 10 mV of each rail providing the maxi mum output dynamic range.Offset voltage of 800 AV max, offset voltage drift of 2 NV/ C, input bias currents below 25 pA and low input voltage noise provide de precision with s

6、ource impedances up to a Gigaohm.1. 8 MHz unity gain bandwidth, -93 dB T II D at 10 kHz and 3 V/M slew rate are provided with a low supply current of 800 MA per amplifier The AD822 drives up to 350 pF of direct capacitive load as a follower, and provides a mini mum output current of 15 mA. This allo

7、ws the amplifier to handle a wide range of load conditions. This combination of ac and de performance, plus the outstanding load drive capability, results in an exceptionally versatile amplifier for the single supply user.The AD822 is available in two performance grades. The A and B grades are rated

8、 over the industrial temperature range of C to +85 C.The A D822 is offered in three varieties of 8-lead package: Plastic DIP, MSOP, and SOIC.100105VVoUT0V (GND)110100Ik10kFigure 2. Gain-of-2 A mplifier; Vs = 5, 0, ViN = 2 5 V SineCentered at 1.25 V, Rb = 100 kQFREQUENCY - HzFigure 1. Input Voltage N

9、oise vs. FrequencyREV. BTel: 781/329-4700Fax: 781/326-8703Information furnished by Analog Devices is believed to be accurate and reliabl e. Ho we ver, no responsibility is assu med by Analog Devices for its use, nor for any infringe ments of patents or other rights of third parties w hich may result

10、 fro m its use. No license is granted by i in plication or otherwise under any patent or patent rights of Analog Devices.One Technology W ay, P. 0. Box 9106, Norwood, MA 02062-9106, U.S. A.www. analog, com Analog Devices, Inc., 20011000Isource = 10mAIsink = 10mA100Isource = 1mAIsink = 1mA10Isource =

11、 10 AIsink = 10 A1-60 - 40 - 2002 04 06 080 1 00 120 140TEMPERATURE - CTPC 19. Output Saturation Voltage vs. Tem perature100908070+PSRR605040-PSRR302010010100 Ik 10k100k IM 10MFREQUENCY - HzTPC 22. Power Supply Rejection vs. Frequency80307015V25Rl = 2k6015V50Vs = 15V-OUT40S = 0Y 5V30s = OV； 3V2010Vs

12、 = OY5V=OV,3V201510S = OY 5VVs = OY 3Vo-60-40 - 20020406080TEMPERATURE - C100120 1400 10k100kIMFREQUENCY - Hz10MTPC 20.Short Circuit Current Li mit vs.Tem p eratureTPC23. LargeSignal Frequency ResponsePo wer Dissipation vs.Temperature for1600T = +125 C 1400T = +25 C1200T = -55 C100080060040020000481

13、2162024283236TOTAL SUPPLY VOLTAGE - VTPC 21. Quiescent Current vs. Supply Voltage vs. Te mperature2.42.22.08-LEADMINI-DIP1.88-LEADSOIC1.61.41.21.00.88-LEADMSOP0.60.40.20.0-60-40-20020406080AMBIENT TEMPERATURE - CTPC 24. Maxim u m Plastic Packages-70OUT-8020k2 2k-900.1 F-100-110-120-130-140300Ik3k10k

14、30k100k300kINFREQUENCY - HzTPC 25.1/2AD822Crosstalk vs. Frequency0.01 F0.01 FRl100pFOUT20V p-p31/2AD8225kCROSSTALK = 20L0GOUTIOVin1/2AD82275k0. 1TPC 28. Crosstalk Test CircuitTPC 26. Unity-Gain FollowerTPC 29. Large Signal Response Unity Gain Follower;Vs二 15 V, Rl= 10 kQTPC 27. 20 V p-p, 25 kHz Sine

15、 Wave Input; Unity Gain Follower; RL= 600 Q Vs = 1 5 VTPC 30. S mall Signal Response Unity Gain Follower; Vs二 15 V, Rj,二 10 kQGNDGNDTPC 31. Vs = 5 V, 0 V; Unity Gain Follower Response to 0 V to 4 V StepTPC 34. Vs = 5 V, 0 V; to 0 V to 5 V StepUnity Gain Follower Response+Vs 0.01 F8VIN1/24 AD822Rl lO

16、OpFVOUTGNDTPC 32. Unity Gain FollowerTPC 35. Vs = 5 V, 0 V; 40 mV Step CenteredUnity Gain Follower Response, to 10 mV Above Ground, RL= 10 kQ10k20kIN+Vs0.01 F81/2AD822VOUTlOOpFGNDTPC 33. Gain-of-Two InverterTPC 36. Vs = 5 V, 0 V;20 mV Step, CenteredGain-of-Two Inverter Response to 20 mV Below Ground

17、, KL = 10 kQGNDGND(a)Inverter Response toGround, RL = 10 k。TPC 37. Vs = 5 V, 0 V; Gain-of-Two2. 5 V Step Centered - L 25 V BelowGNDTPC 38. Vs = 3 V, 0 V; Gain-of-Two Inverter, ViN= 1. 25 V, 25 kHz, Sine Wave Centered at -Q 75 V, R. = 600 Q+VsGND(b)5VRp*IN“OUTTPC 39. (a) Response with RP= 0; V1N from

18、 0 to +VS (b) VN = 0 to+Vs + 200 mVVoUT - 0 to +VsRP= 49.9kQAPPLICATION NOTESINPUT CHARACTERISTICSIn the AD822, n-channel JFETs are used to provide a low offset, low noise, high impedance input stage. Minima m input common- mode voltage extends from 0. 2 V below - Vs to 1 V less than +VS. Driving th

19、e input voltage closer to the positive rail will cause a loss of amplifier bandwidth (as can be seen by comparing the large signal responses shown in TP Cs 31 and 34) and increased com mon-mode voltage error as illustrated in TPC 17.The AD822 does not exhibit phase reversal for input voltages lid lp

20、nand including +VS. IPX 39aAshoAys. the response of an A uo22 voltage follower to a U v to 5 V (+V ； square waveSinput Th.e input andoutput are superimposed. The output tracks the input up to +V without phase reversal. 1 he reducedSbandwidth above a 4 V input causes the rounding of the output wave l

21、oi in. rur input villages gretuer uitui t v , a lesitiioi inSseries with the A D822 s noninverting input will prevent phase reversal, at the expense of greater input voltage noise This is illustrated in TPC 39b.Since the input stage uses n-channel JFETs, input current during nor mal operation is neg

22、ative; the current flows out fro m the input terminals. If the input voltage is driven more positive than +VS - 0. 4 V, the input current will reverse direction as internal device junctions becom e forward biased This is illustrated in TPC 4.A current limiting resistor should be used in series with

23、the input of the AD822 if there is a possibility of the input voltage exceeding the positive supply by more than 300 mV, or if an input voltage will be applied to the AD822 when Vs = 0. The amplifier will be damaged if left in that condition for more than 10 seconds. A 1 kQresistor allows the amplif

24、ier to withstand up to 10 V of continuous overvoltage, and increases the input voltage noise by a negligible amount.Input voltages less than - Vs are a completely different story. The amplifier can safely withstand input voltages 20 V below the minus supply voltage as long as the total voltage from

25、the positive supply to the input teim i nal is less than 36 V. In addition, the input stage typically m aintains picoamp level input currents across that input voltage range.T he A D822 is designed for 13 nV/V Hz wideband input voltage noise and maintains low noise performance to low frequencies (re

26、fer to TPC 11). This noise performance, along with the A D822 s low input current and current noise means that the A D822 contributes negligible noise for applications with source resistances greater than 10 kQand signal band widths greater than 1 kHz. This is illustrated in Figure 3.100kWHENEVER JO

27、HNSON NOISE IS GREATER THAN AMPLIFIER NOISE, AMPLIFIER NOISE CAN BE 10k CONSIDERED NEGLIGIBLE FOR APPLICATION.1kHzIkRESISTOR JOHNSONNOISE1001010Hz1AMPLIFIER-GENERATED NOISE 0.110k100k IM 10M100M 1G 10GSOURCE IMPEDANCE -Figure 3. Total Noise vs. Source ImpedanceOUTPUT CHARACTERISTICSThe A D822 s uniq

28、ue bipolar rail-to-rail output stage swings within 5 mV of the minus supply and 10 mV of the positive supply with no external resistive load. The AD822 sapproximate output saturation resistance is 40 Qsourcing and 20 Qsinking. T his can be used to esti mate output saturation voltage when driving hea

29、vier current loads. For instance, when sourcing 5 mA, the saturation voltage to the positive supply rail will be 200 mV, when sinking 5 mA, the saturation voltage to the minus rail will be 100 mV.The amplified sopen-loop gain characteristic will change as a function of resistive load, as shown in TP

30、Cs 7 through 10. For load resistances over 20 kQ the A D822 sinput error voltage is virtually unchanged until the output voltage is driven to 180 mV of either supply.If the AD822 soutput is overdriven so as to saturate either of the output devices, the amplifier will recover within 2 用 of its input

31、returning to the amplifier slinear operating regioaDirect capacitive loads will interact with the am plifief s effective output impedance to form an additional pole in the amplifiers feedback loop, which can cause excessive peaking on the pulse response or loss of stability. Worst-case is when the a

32、mplifier is used as a unity gain follower. Figure 4 shows the AD822 s pulse response as a unity gain follower driving 350 pF. This amount of overshoot indicates approxi mately 20 degrees of phase margin-the system is stable, but is nearing the edge. Configurations with less loop gain, and as a resul

33、t less loop bandwidth, will be much less sensitive to capacitance load effects. Figure 5 is a plot of capacitive load that will result in a 20 degree phase margin versus noise gain for the A 1)822. Noise gain is the inverse of the feedback attenuation factor provided by the feedback network in use.F

34、igure 4. S m all Signal Response of AD822 as Unity GainFollower Driving 350 pFFigure 6 shows a method for extending capacitance load drive capability for a unity gain follow er. With these component values, the circuit will drive 5, 000 pF with a 10% overshoot+vs0.01 F 81/2iooAD822vOUT 0.01 F4Clvs20

35、pF20kFigure 6. Extending Unity Gain Follower Capacitive Load Capability Beyond 350 pFAPPLICATIONSSingle Supply Voltage-to-Frequency ConverterThe circuit shown in Figure 7 uses the A D 822 to drive a low power timer, which produces a stable pulse of width ti. The positive going output pulse is integr

36、ated by Rl-Cl and used as one input to the A D822, which is connected as a differential integrator The other input (nonloading) is the unknown voltage, VIN. The AD822 output drives the timer trigger input, closing the overall feedback loop.+ 10VC50.1U4REF-02V = 5V REF1300Ik3k10k30kCAPACITIVE LOAD FO

37、R 200 PHASE MARGIN-pFRscale* 10kCMOS 74HCO4U3B 4U3A2C30.1 FOUT20UT1499kR21%0.01F,2%U2CMOS 555UIClR3* 116kTHRRf、RIFigure 5. Capacitive Load Tolerance vs. Noise Gain1/2AD822BOUTTRVin499k 1%C20.01 F,2%C6 390pF 5% (NPO)DISGND1CVC4 0.010V TO 2.5VFULL SCALENOTES:R3 C6four = Vin/(Vref ti), ti = L 1=25kHz F

38、s AS SHOWN* = 1% METAL FILM, 50ppm/ C TC* = 10% 20T FILM, 100ppm/ C TCti=33 s FOR foui = 20kHz Vin = 2 0VFigure 7. Single Supply Voltage-to-Frequency ConverterT y pi cal A D822 bias currents of 2 pA allow megoh m-range source impedances with negligible de errors Linearity errors on the order of 0. 0

39、1 % full scale can be achieved with this circuit This performance is obtained with a 5 V single supply which delivers less than 1 mA to the entire circuitSingle Supply Program mable Gain Instrumentation Amplifier The A D822 can be configured as a single supply instrumentation amplifier that is able

40、to operate from single supplies down to 3 V, or dual supplies up to 15 V. Using only one A D822 rather than three separate op amps, this circuit is cost and power efficient AD822 FET inputs 2pA bias currents minimize offset errors caused by high unbalanced source impedances.An array of precision thi

41、n4ilm resistors sets the in amp gain to be either 10 or 100. These resistors are laser-tri m med to ratio match to 0. 01%, and have a maxi mu m differential TC of 5 ppm/ CVrefVlNlIN2Table L AD822 In Amp PerformanceParametersVs = 3 V, 0 VVs = 5 VC MRR74 dB80 dBC o m m o n- M o d eV oltage Range-Q2 V

42、to +2 V-5 2 V to +43 dB B W, G = 10180 kHz180 kHzG 二 10018 kHz18 kHztsETTLING2 V Step (Vs = 0 V, 3 V)2 Ms5 V (Vs =5 V)5 MsNoise f = 1 kHz, G = 10270 nV/VHz270 nV/V HzG 二 1002. 2 2/J Hz2. 2 3/J HzIsupply (Total)1. 10 mA1. 15 mAFigure 8a. Pulse Response of In Amp to a 500 mV p-pInput Signal; Vs = 5 V,

43、 0 V; Gain = 10RI 90k=10R2 9kR3Ik=100o. iR4IkG = 100R5 9kR690k=10OHMTEKPART # 1043Rp lkRP lk1/2AD8221/2AD822VoUT(G = 10) VOUT(G = 100) Vout = (ViniINI- VlN2 )喏正-T州R5 + R6(1+ -R4) +vREFFigure 8b. A Single Supply Progra m m ab le Instru m e ntatio n A m plifier1 F MYLAR CHANNEL 195.3k1 FMYLARCHANNEL 2

44、3V95.3k0F 0.1 F1/247.5kAD822500 F4.99kL10kHEADPHONES32 IMPEDANCE10k4.99kp47,5kAD822500 FFigure 9. 3 V Single Supply Stereo Headphone Driver3 V, Single Supply Stereo Headphone DriverThe AD822 exhibits good current drive and T H D + N perfbL ma nee, even at 3 V single supplies. At 1 kHz, total harmoni

45、c distortion plus noise (T H D + N) equals -62 dB (0. 079 %) for a 300 mV p-p output signal. This is comparable to other single supply op amps which consume more power and cannot run on 3 V power suppliesIn Figure 9, each channel sinput signal is coupled via a 1 MF M ylar capacitor. Resistor dividers set the de voltage at the noninverting inputs so that the output voltage is midway between the power supplies (1. 5 V). T he gain is 1. 5. Each half of the A 1)822 c