AD7872 AD [Analog Devices], AD7872 Datasheet
AD7872
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AD7872 Summary of contents
Page 1
... The AD7871 offers a choice of three data output formats: a sin- gle, parallel, 14-bit word; two 8-bit bytes or a 14-bit serial data stream. The AD7872 is a serial output device only. The two parts are capable of interfacing to all modern microprocessors and digital signal processors. ...
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... AD7871/AD7872–SPECIFICATIONS Parameter 2 DYNAMIC PERFORMANCE 3 Signal-to-Noise Ratio (SNR MIN MAX Total Harmonic Distortion (THD) Peak Harmonic or Spurious Noise Intermodulation Distortion (IMD) Second Order Terms Third Order Terms Track/Hold Acquisition Time DC ACCURACY Resolution Minimum Resolution for Which No Missing Codes Are Guaranteed ...
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... ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD7871/AD7872 features proprietary ESD protection circuitry, permanent dam- age may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality ...
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... AD7871/AD7872 AD7871 PIN FUNCTION DESCRIPTION DIP No. Mnemonic Function 1 CONVST Convert Start. A low to high transition on this input puts the track/hold into the hold mode. This input is asynchronous to the CLK. CS and RD must be held high for the duration of this pulse Chip Select. Active low logic input. The device is selected when this input is active. With CONVST tied low, a new conversion is initiated when CS goes low ...
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... AD7872 PIN FUNCTION DESCRIPTION DIP No. Mnemonic Function 1 CONTROL Control Input. With this pin the SCLK is noncontinuous; with this pin at –5 V, the SCLK is continuous. 2 CONVST Convert Start. A low to high transition on this input puts the track/hold into the hold mode. This input is asynchronous to the CLK. ...
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... When the AD7871/AD7872’s offset and full-scale errors need to be adjusted, offset error must be adjusted first. This is achieved by trimming the offset of the op amp driving the analog input of the AD7871/AD7872 while the input voltage is 1/2 LSB below AGND. The trim procedure is as follows: apply a voltage of –0.183 mV (–1/2 LSB offset voltage until the ADC output code flickers between 11 1111 1111 1111 and 00 0000 0000 0000 ...
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... UNIPOLAR OPERATION A typical unipolar circuit is shown in Figure 7. The AD7871/ AD7872 REF OUT is used to offset the analog input The analog input range is determined by the ratio R4. The minimum range with which the circuit will work ...
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... V or –5 V and in this case the DB12/SSTRB, DB11/SCLK and DB10/SDATA pins assume their serial func- tions. The AD7872 is a serial output device only. The serial function on both devices is identical. Serial data is available dur- ing conversion with a word length of 16 bits; two leading zeros, followed by the 14-bit conversion result starting with the MSB ...
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... Figure 10. Mode 1 Timing Diagram, Byte or Serial Read Figure 11. Mode 2 Timing Diagram, 14-Bit Parallel Read Figure 12. Mode 2 Timing Diagram, Byte or Serial Read REV. D AD7871/AD7872 –9– ...
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... A Fast Fourier Transform (FFT) plot is generated from which the SNR data can be ob- tained. Figure 13 shows a typical 2048 point FFT plot of the AD7871/AD7872, with an input signal of 10 kHz and a sam- pling frequency of 83 kHz. The SNR obtained from this graph ...
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... AD7872 is a dedicated serial output device. The fast data access times on the parallel modes of the AD7871 allow interfacing to the very fast DSPs. The se- rial mode on both the AD7871 and AD7872 is compatible with the serial port structures on all the popular DSPs. Parallel Read Interfacing Figures 17 and 18 show interfaces to the ADSP-2100 and the TMS32020/C25 DSP processors ...
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... DSPs. In all three interfaces, CONVST is used to start conversion since this does not activate the parallel bus. Thus, the microprocessor can continue to use its parallel bus re- gardless of the state of the AD7872. The interfaces show a timer driving the CONVST input but this could be generated from a decoded address if required. ...
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... LK1 on the PCB) on the analog input track. If this shorting plug is used, the analog input connects to the buffer amplifier driving the AD7871/ AD7872; if this shorting plug is omitted, a wire link can be used to connect the analog input to the PCB component grid. INTERFACE CONNECTIONS There are two parallel connectors labeled SKT4 and SKT6, and one serial connector labeled SKT5 ...
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... AD7871/AD7872 Figure 24. Data Acquisition Circuit Using the AD7871/AD7872 Figure 25. PCB Silkscreen for Figure 24 –14– REV. D ...
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... Figure 26. PCB Component Side Layout for Figure 24 REV. D Figure 27. PCB Solder Side Layout for Figure 24 –15– AD7871/AD7872 ...
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... STANDOFF 0.01 (0.254) SEATING (1.27) 0.014 (0.356) PLANE BSC Relative Package 1 3 Model Accuracy Option N-28A AD7872AN – + dBs min AD7872JN 1 max N-28A AD7872KN +70 C P-28A AD7872BR 1 max P-28A 1 max Q-28 AD7872JR AD7872KR + AD7872TQ NOTES 1 To order MIL-STD-883, Class B, processed parts, add /883B to part number ...