ltc1967 Linear Technology Corporation, ltc1967 Datasheet

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... The LTC1967 allows hassle-free system calibra- tion at any input voltage. The LTC1967 has a rail-to-rail output with a separate out- put reference pin providing flexible level shifting; it oper- ates on a single power supply from 4.5V to 5.5V. A low power shutdown mode reduces supply current to 0 ...

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... Input Currents (Note 2) ..................................... 10mA Output Current (Note 3) ..................................... 10mA ENABLE Voltage ......................................... –0. OUT RTN Voltage ........................................ –0. Operating Temperature Range (Note 4) LTC1967C/LTC1967I ......................... – Specified Temperature Range (Note 5) LTC1967C/LTC1967I ......................... – Maximum Junction Temperature ......................... 150 C Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec) ...

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... Note 4: The LTC1967C/LTC1967I are guaranteed functional over the operating temperature range of – Note 5: The LTC1967C is guaranteed to meet specified performance from The LTC1967C is designed, characterized and expected to meet specified performance from – but is not tested nor QA sampled at these temperatures. The LTC1967I is guaranteed to meet specified performance from – ...

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... LTC1967 ELECTRICAL CHARACTERISTICS Note 13: The common mode rejection ratios of the LTC1967 are measured with DC inputs from 50mV to 350mV. The input CMRR is defined as the change in V measured between input levels 350mV and input IOS + + + levels of V – 350mV to V divided by V – 350mV. The output CMRR is ...

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... SUPPLY VOLTAGE (V) Input Signal Bandwidth vs RMS Value 1000 300 0.1% ERROR 1% ERROR 200 100 100 0 –100 10 –200 –300 –400 1 6 100 1k 10k 100k INPUT SIGNAL FREQUENCY (Hz) LTC1967 AC Linearity 0.20 60Hz SINEWAVES 0.15 AVE 1kHz V = MIDSUPPLY IN2 0.10 0.05 0 –0.05 –0.10 –0.15 –0. 100 200 ...

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... LTC1967 W U TYPICAL PERFOR A CE CHARACTERISTICS Bandwidth to 200kHz 202 0.5%/DIV AVE 201 200 199 198 197 196 195 50k 100k 200k 0 150k INPUT FREQUENCY (Hz) 1967 G14 Output Accuracy vs Signal Amplitude 10 1% ERROR 5 0 –5 –1% ERROR –10 AC – 60Hz –15 SINEWAVE – ...

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... AC and DC. Although it is often tied to GND, it can be tied to any arbitrary voltage: GND < OUT RTN < (Pin 7): Positive Voltage Supply. 4.5V to 5.5V. ENABLE (Pin 8): An Active-Low Enable Input. LTC1967 is debiased if open circuited or driven to V operation, pull to GND – IN ...

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... For the purposes of this data sheet, “SCR Waveforms” refers to the ideal chopped sine wave, though the LTC1967 will do faithful RMS-to-DC conversion with real SCR waveforms as well. The case shown is for = 90 , which corresponds to 50% of available power being delivered to the load ...

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... This topology is inherently more stable and linear than log/ antilog implementations primarily because all of the signal processing occurs in circuits with high gain op amps operating closed loop. More detail of the LTC1967 inner workings is shown in the Simplified Schematic towards the end of this data sheet. INPUT CIRCUITRY INPUT • ...

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... RMS value, the peak is necessarily present for at most 6.25% (1/16) of the time. The LTC1967 performs very well with crest factors less and will respond with reduced accuracy to signals with higher crest factors. The high performance with crest factors less than 4 is directly attributable to the high linearity throughout the LTC1967 ...

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... C = 1.5 F and f AVE INPUT If the application calls for the output of the LTC1967 to feed a sampling or Nyquist A/D converter (or other circuitry that will not average out this double frequency ripple) a larger averaging capacitor can be used. This trade-off is depicted in Figure 8. The peak ripple error can also be ...

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... The first one, shown in Figure 9a uses a coupling capacitor to one input while the other is grounded. This will remove the DC voltage difference from the input to the LTC1967, and it will therefore not be part of the resulting output voltage. Again, this connection will + ...

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... To convince oneself of this necessity, consider a pulse train of 50% duty cycle between 0mV and 100mV. At very low frequencies, the LTC1967 will essentially track the input. But as the input frequency is increased, the average result will converge to the RMS value of the input. If the rise and fall characteristics were symmetrical, the output would converge to 50mV ...

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... However, if the reason for choosing 100 keep the peak error with a 10Hz input less than 0.1%, there is another way to achieve that result with a much improved settling time. 0.2 0.25 1967 F10a = 1 F Figure 10b. LTC1967 Falling Edge with C AVE SETTLING TIME (SEC) Figure 11 ...

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... First of all, the op amp can be operated split supply if a negative supply is available. Just the op amp would need to do so; the LTC1967 can remain single sup- ply. A second way to address this issue is to create a signal reference voltage a half volt or so above ground. This is most ...

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... The initial rise of the LTC1967 will have enhanced slew rates with DC and very low frequency inputs due to saturation effects in the modulator ...

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... DC offset, the square of the input has frequency content at the input frequency and the filter must average out that lower frequency. So with waveforms, the re- quired value for C input frequency, using the same design curves presented in Figures and 17. LTC1967 0.22 F 100 1967 F16 ...

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... LTC1967 U U APPLICATIO S I FOR ATIO 0 0. 0.1 0. 0.1 0.01 0.1 Crest factor, which is the peak to RMS ratio of a dynamic signal, also effects the required C AVE crest factor, more of the energy in the signal is concentrated into a smaller portion of the waveform, and the averaging has to ride out the long lull in signal activity ...

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... PEAK With the droop is only – 0.929% to 247.7mV AVE and the peak/output ratio is just 4.038, which the LTC1967 has enough margin to handle without error. For crest factors less than 3.5, the selection of C previously described should be sufficient to avoid this droop and modulator saturation effect. But with crest factors above 3 ...

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... Cookbook for a discussion of the DC conversion error with low frequency AC inputs. The LTC1967 bandwidth limita- tions cause additional errors with high frequency inputs. Another dynamic error is due to crest factor. The LTC1967 performance versus crest factor is shown in the Typical Performance Characteristics. Output Errors Versus Frequency ...

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... Another type of ADC that has inherent rejection of RMS averaging ripple is an oversampling LTC2420. Its input impedance is 6.5M , but only when it is sampling. Since this occurs only half the time at most directly loads the LTC1967, a gain error of –0.32% to –0.43% results. In fact, the LTC2420 DC input current is LTC1967 to OUT RTN so that C ...

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... These errors will vary from part to part, but with a specific LTC1967 and LTC2420 combination, the errors will be fixed, varying less than 0.05% over temperature system that has digi- tal calibration can be quite accurate despite the nominal gain and offset error ...

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... DC-based calibration is preferable in many cases because a DC voltage of known, good accuracy is easier to gener- ate than such an AC calibration voltage. The only down side is that the LTC1967 input offset voltage plays a role therefore suggested that a DC-based calibration scheme check at least two points: full scale. Applying the ...

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... APPLICATIO S I FOR ATIO TROUBLESHOOTING GUIDE Top Ten LTC1967 Application Mistakes 1. Circuit won’t work–Dead On Arrival–no power drawn. – Probably forgot to enable the LTC1967 by pulling Pin 8 low. Solution: Tie Pin 8 to Pin 1. 2. Circuit won’t work, but draws power. Zero or very little output, single-ended input application. – ...

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... APPLICATIO S I FOR ATIO 7. Output is noisy with >50kHz inputs. – This is a fundamental characteristic of this topol- ogy. The LTC1967 is designed to work very well with inputs of 20kHz or less. It works okay as high as 1MHz, but it is limited by aliased Solution: Bandwidth limit the input or digitally filter the resulting output ...

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... MAX T1 50Hz TO 400Hz AVE 0.1 F C12 C9 OUTPUT C11 A2 OUT RTN C10 CLOSED DURING SHUTDOWN 50k BLEED RESISTOR FOR C AVE + V IN1 LTC1967 OUT OUT C AVE IN2 OUT RTN 1 F 20k GND EN 1967 TA03 20k T1: CR MAGNETICS CR8348-2500-N www.crmagnetics.com C AVE 1967 SS = 4mV ...

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... DETAIL “A” MAX SEATING PLANE 0.22 – 0.38 (.009 – .015) TYP LTC1967 RMS Noise Measurement 2.5V 2. OUT 1 V LTC1967 1k 1/2 IN1 V OUT LTC6203 IN2 OUT RTN GND EN –2.5V 1967 TA05 0.1 F 100k –2.5V BW 1kHz TO 100kHz INPUT SENSITIVITY = 1 V 0.52 (.0205) 8 ...

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... 2.49k – 5. R10 LTC1967 200k V OUT C4 OUT RTN 0.33 F GND EN COMMENTS Available in SO-8 or SOT-223 Q 375 V V OS(MAX 800 1.2mA I , 150 150 ...