AD7870 Analog Devices, AD7870 Datasheet
AD7870
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AD7870 Summary of contents
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... All parts operate from 5 V power supplies. The AD7870 and AD7876 accept input signal ranges and 10 V, respec- tively, while the AD7875 accepts a unipolar input range ...
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... Temperature ranges are as follows Versions + Versions; – + Versions; – +125 (pk-pk SNR calculation includes distortion and noise components. 4 Measured with respect to internal reference and includes bipolar offset error. 5 Sample tested @ + ensure compliance. Specifications subject to change without notice. AD7870 Units ...
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... A max max max 7/9 7/9 7/9 s min/ s max As per AD7870 –3– AD7870/AD7875/AD7876 Test Conditions/Comments Typical Full-Scale Error Is 1 LSB Typical ppm kHz Sine Wave 100 kHz IN SAMPLE Typically 71.5 dB for 0 < V < 50 kHz kHz Sine Wave, f ...
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... Digital Outputs to DGND . . . . . . . . . . . –0 Operating Temperature Range Commercial ( Versions – AD7870 +70 C Commercial (K, L Versions – AD7875 +70 C Industrial ( Versions – AD7870 .– +85 C Industrial (B, C Versions – AD7875/AD7876 – +85 C Extended (S, T Versions – +125 C Storage Temperature Range . . . . . . . . . . . . . – ...
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... To order MIL-STD-883, Class B, processed parts, add /883B to the part number. Contact local sales office for military data sheet Narrow Plastic DIP Cerdip Small Outline IC (SOIC). 3 Available to /883B processing only. REV. B AD7870/AD7875/AD7876 AD7870 ORDERING GUIDE V Voltage SNR IN Range (V) (dBs min ...
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... REF OUT Voltage Reference Output. The internal 3 V reference is provided at this pin. The external load capability is 500 Analog Input. The analog input range for the AD7870 for the AD7876 and for the AD7875 Negative Supply, –5 V ...
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... ANALOG INPUT The three parts differ from each other in the analog input volt- age range that they can handle. The AD7870 accepts 3 V input signals, the AD7876 accepts input range, while the input range for the AD7875 ...
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... Where adjustment is required, offset error must be adjusted be- fore full-scale error. This is achieved by trimming the offset of the op amp driving the analog input of the AD7870 while the input voltage is 1/2 LSB below ground. The trim procedure is as follows: apply a voltage of –0.73 mV(–1/2 LSB and adjust the op amp offset voltage until the ADC output code flickers between 1111 1111 1111 and 0000 0000 0000 ...
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... OFFSET AND FULL-SCALE ADJUSTMENT—AD7875 Similar to the AD7870, most of the DSP applications in which the AD7875 will be used will not require offset and full-scale adjustment. For applications that do require adjustment, offset error must be adjusted before full-scale (gain) error. This is achieved by applying an input voltage of 0.61 mV (1/2 LSB) to ...
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... AD7870/AD7875/AD7876 Figure 10. Mode 1 Timing Diagram, Byte or Serial Read The Mode 1 timing diagram for byte and serial data is shown in Figure 10. INT goes low at the end of conversion and is reset high by the first falling edge of CS and RD. This first read at the end of conversion can either access the low byte or high byte of data depending on the status of HBEN (Figure 10 shows low byte only for example) ...
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... SNR data can be ob- tained. Figure 13 shows a typical 2048 point FFT plot of the AD7870KN/AD7875KN with an input signal of 25 kHz and a sampling frequency of 100 kHz. The SNR obtained from this graph is 72.6 dB. It should be noted that the harmonics are taken into account when calculating the SNR ...
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... In this case, the input consists of two, equal amplitude, low distortion sine waves. Figure 15 shows a typical IMD plot for the AD7870/ AD7875. Peak Harmonic or Spurious Noise Peak harmonic or spurious noise is defined as the ratio of the ...
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... MICROPROCESSOR INTERFACE The AD7870/AD7875/AD7876 has a wide variety of interfacing options. It offers two operating modes and three data-output for- mats. Fast data access times allow direct interfacing to most mi- croprocessors including the DSP processors. Parallel Read Interfacing Figures show interfaces to the ADSP-2100, TMS32010 and the TMS32020 DSP processors ...
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... SICLK. Figure 22. NEC7720 Serial Interface TMS32020 Serial Interface Figure 23 shows a serial interface between the AD7870/ AD7875/ AD7876 and the TMS32020. The AD7870/AD7875/AD7876 is configured for continuous clock operation. Note, the ADC will not interface correctly to the TMS32020 if the ADC is config- ured for a noncontinuous clock ...
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... STAND-ALONE OPERATION The AD7870/AD7875/AD7876 can be used in its Mode 2, par- allel interface mode for stand-alone operation. In this case, con- version is initiated with a pulse to the ADC CS input. This pulse must be longer than the conversion time of the ADC. The BUSY output is used to drive the RD input. Data is latched from the ADC DB0– ...
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... SKT6). The –5 V supply required by the ADC is generated from a voltage regulator on the V– power supply input (IC3 in Figure 27). COMPONENT LIST IC1 AD711 Op Amp IC2 AD7870/AD7875/AD7876 Analog-to- Digital Converter IC3 MC79L05 –5 V Regulator IC4 74HC00 Quad NAND Gate IC5 ...
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... Figure 28. Data Acquisition Circuit Using the AD7870/AD7875/AD7876 REV. B Figure 29. PCB Silkscreen for Figure 28 –17– AD7870/AD7875/AD7876 2 ...
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... AD7870/AD7875/AD7876 Figure 30. PCB Component Side Layout for Figure 28 Figure 31. PCB Solder Side Layout for Figure 28 –18– REV. B ...
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... Plastic DIP (N-24) 24-Pin Cerdip (Q-24) REV. B OUTLINE DIMENSIONS Dimensions shown in inches and (mm). –19– AD7870/AD7875/AD7876 28-Pin PLCC (P-28A) 24-Pin SOIC (R-24) 2 ...
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