Simplicity 1967 Specifikace

1LTC19671967fPrecision ExtendedBandwidth, RMS-to-DC Converter High Linearity:0.02% Linearity Allows Simple System Calibration Wide Input Bandwidth:Ban

10LTC19671967fBecause this peak has energy (proportional to voltagesquared) that is 16 times (42) the energy of the RMS value,the peak is necessarily

11LTC19671967fAPPLICATIO S I FOR ATIOWUUUbecause of the computation of the square of the input. Thetypical values shown, 5% peak ripple with 0.05%

12LTC19671967fInput ConnectionsThe LTC1967 input is differential and DC coupled. TheLTC1967 responds to the RMS value of the differentialvoltage betwe

13LTC19671967fOutput ConnectionsThe LTC1967 output is differentially, but not symmetri-cally, generated. That is to say, the RMS value that theLTC1967

14LTC19671967f100mV to 110mV (+10%) and back (–10%), the stepresponses are essentially the same as a standard expo-nential rise and decay between thos

15LTC19671967fReducing Ripple with a Post FilterThe output ripple is always much larger than the DC error,so filtering out the ripple can reduce the p

16LTC19671967fAPPLICATIO S I FOR ATIOWUUUsomewhat lower (≈0.7 • 1.45 ≈ 1Hz) than with 2.2µFalone. To adjust the bandwidth of either of them, simpl

17LTC19671967fAPPLICATIO S I FOR ATIOWUUUFigures 18 and 19 show the settling time versus settlingaccuracy for the Buffered and DC accurate post fi

18LTC19671967fAPPLICATIO S I FOR ATIOWUUUCrest factor, which is the peak to RMS ratio of a dynamicsignal, also effects the required CAVE value. Wi

19LTC19671967fwaveform dynamics and the type of filtering used. Theabove method is conservative for some cases and aboutright for others.The LTC1967 w

2LTC19671967fSupply VoltageV+ to GND... 6VInput Currents (Note 2) ...

20LTC19671967fVOUT = (√(5mV AC)2 + (0.2mV DC)2) • 1.001 + 0.1mV= 5.109mV= 5mV + 2.18%As can be seen, the gain term dominates with large inputs,while t

21LTC19671967fAPPLICATIO S I FOR ATIOWUUUdevoted to sampling, ten time constants elapse. Thisallows each sample to settle to within 46ppm and it i

22LTC19671967fnot zero at 0V, but rather at one half its reference, so bothan output offset and a gain error will result. These errorswill vary from p

23LTC19671967fThe trade-off here is that on the one hand, the DC error isinput frequency dependent, so a calibration signal fre-quency high enough to

24LTC19671967fAPPLICATIO S I FOR ATIOWUUUTROUBLESHOOTING GUIDETop Ten LTC1967 Application Mistakes1. Circuit won’t work–Dead On Arrival–no power d

25LTC19671967fAPPLICATIO S I FOR ATIOWUUU7. Output is noisy with >50kHz inputs.– This is a fundamental characteristic of this topol-ogy. The LT

26LTC19671967fTYPICAL APPLICATIO SUSI PLIFIED SCHE ATICWW5V Single Supply, Differential,AC-Coupled RMS-to-DC ConverterSingle Supply RMS Current M

27LTC19671967fUPACKAGE DESCRIPTIOMS8 Package8-Lead Plastic MSOP(Reference LTC DWG # 05-08-1660)Information furnished by Linear Technology Corporation

28LTC19671967f LINEAR TECHNOLOGY CORPORATION 2004 LT/TP 0504 1K • PRINTED IN USALinear Technology Corporation1630 McCarthy Blvd., Milpitas, CA 95035

3LTC19671967fThe ● denotes specifications which apply over the full operatingtemperature range, otherwise specifications are TA = 25°C. V+ = 5V, VOUTR

4LTC19671967fELECTRICAL CHARACTERISTICSNote 13: The common mode rejection ratios of the LTC1967 are measuredwith DC inputs from 50mV to 350mV. The inp

5LTC19671967fTYPICAL PERFOR A CE CHARACTERISTICS UWPerformance vs Large Crest FactorsAC LinearityDC Linearity Supply Current vs Supply VoltageSupp

6LTC19671967fTYPICAL PERFOR A CE CHARACTERISTICS UWBandwidth to 200kHzDC Transfer Function Near ZeroInput Common Mode RejectionRatio vs FrequencyO

7LTC19671967fGND (Pin 1): Ground. The power return pin.IN1 (Pin 2): Differential Input. DC coupled (polarity isirrelevant).IN2 (Pin 3): Differential I

8LTC19671967fthe lowpass filter. The input to the LPF is the calculationfrom the multiplier/divider; (VIN)2/VOUT. The lowpassfilter will take the aver

9LTC19671967fAPPLICATIO S I FOR ATIOWUUUNote that the internal scalings are such that the ∆Σ outputduty cycle is limited to 0% or 100% only when V