AD7871 Analog Devices, AD7871 Datasheet
AD7871
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AD7871 Summary of contents
Page 1
... The on-chip clock may be overridden to synchronize ADC operation to the digital system for minimum noise. 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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... Analog Input. The input range Negative Supply, – Positive Supply for analog circuitry DIP REV enables the internal laser-trimmed oscillator. 5%. 5%. 5%. Pin 16 and Pin 9 should be connected together. PIN CONFIGURATIONS DIP, SOIC –5– AD7871/AD7872 PLCC ...
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... If the CONVST input is used to start conversion, then the track to hold transition occurs on the rising edge of CONVST the AD7871 starts conversion, this transition occurs on the fall- ing edge of CS. ANALOG INPUT Figure 4 shows the AD7871/AD7872 analog input. The analog input range into an input resistance of typically 15 k ...
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... When this data format is selected, the DB13/HBEN pin assumes the HBEN function. HBEN selects which byte of data read from the AD7871. When HBEN is low, the lower eight bits of data are placed on the data bus during a read opera- tion; with HBEN high, the upper six bits of the 14-bit word are – ...
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... OR-gated with the AD7871 CS input. In some applications, de- pending on power supply turn-on time, the AD7871/AD7872 may perform a conversion on power-up. In this case, the INT line on the AD7871 will power up low, and a dummy read to the device will be required to reset the INT line before starting conversion. ...
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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. ...
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... Both the AD7871 and the AD7872 have an identical serial in- terface. The diagrams that follow show the AD7872 interfaces only, but the AD7871 could just as easily be used in these cir- cuits. Figures 19, 20 and 21 show the AD7872 connected to three popular DSPs. In all three interfaces, CONVST is used to start conversion since this does not activate the parallel bus ...
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... ADSP-2100 Evaluation Board Prototype Expansion Connector. The expansion connector on the ADSP-2100 has eight decoded chip enable outputs labeled ECE1 to ECE8. ECE6 is used to drive the AD7871 CS input on the board. To avoid selecting the onboard RAM sockets at the same time, LK6 on the ADSP-2100 board must be removed. ...
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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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... AD7871/AD7872 AD7871 ORDERING GUIDE Temperature 1, 2 Model Range SNR AD7871JN + dBs min AD7871KN + dBs min AD7871JP + dBs min AD7871KP + dBs min 4 AD7871TQ – +125 C 79 dBs min NOTES 1 To order MIL-STD-883, Class B, processed parts, add /883B to part number ...