AD7641 Analog Devices, AD7641 Datasheet
AD7641
Specifications of AD7641
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AD7641 Summary of contents
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... The AD7641 MSPS, charge redistribution, 18-bit SAR ADC. 2. Superior Linearity. The AD7641 has no missing 18-bit code. 3. Internal Reference. The AD7641 has a 2.048 V internal reference with a typical drift of ±10 ppm/°C and Single-Supply Operation. The AD7641 operates from a 5. Serial or Parallel Interface. ...
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... Multiplexed Inputs ..................................................................... 17 Driver Amplifier Choice ........................................................... 17 Voltage Reference Input ............................................................ 18 Power Supply............................................................................... 20 Conversion Control ................................................................... 20 Interfaces.......................................................................................... 21 Digital Interface.......................................................................... 21 Parallel Interface......................................................................... 21 Serial interface ............................................................................ 22 Master Serial Interface............................................................... 22 Slave Serial Interface .................................................................. 24 Microprocessor Interfacing....................................................... 26 Application Hints ........................................................................... 27 Layout .......................................................................................... 27 Evaluating the AD7641 Performance ...................................... 27 Outline Dimensions ....................................................................... 28 Ordering Guide .......................................................................... 28 Rev Page ...
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... AD7641 Unit Bits μA ns MSPS ms ns MSPS 4 LSB 4 LSB Bits LSB LSB LSB LSB ppm/° FSR ppm/°C LSB ...
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... AD7641 Parameter Turn-On Settling Time REFBUFIN Output Voltage REFBUFIN Output Resistance EXTERNAL REFERENCE Voltage Range Current Drain REFERENCE BUFFER REFBUFIN Input Voltage Range REFBUFIN Input Current TEMPERATURE PIN Voltage Output Temperature Sensitivity Output Resistance DIGITAL INPUTS Logic Levels ...
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... See Table 383/500 12 pF; otherwise, the load maximum. L AD7641 Max Unit 385/520 385/520 385/520 ...
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... AD7641 Table 4. Serial Clock Timings in Master Read After Convert Mode DIVSCLK[1] DIVSCLK[0] SYNC to SCLK First Edge Delay Minimum Internal SCLK Period Minimum Internal SCLK Period Maximum Internal SCLK High Minimum Internal SCLK Low Minimum SDOUT Valid Setup Time Minimum SDOUT Valid Hold Time Minimum ...
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... Specification is for the device in free air: −0 +5.5 V 48-Lead LQFP; θ 4 Specification is for the device in free air: ±20 mA 48-Lead LFCSP; θ 700 mW 2.5 W 125°C –65°C to +125°C Rev Page AD7641 = 91°C/W, θ = 30°C/ 26°C/W. JA ...
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... RDC/SDIN = low), these inputs can be used to slow down the internally generated serial clock that clocks the data output. In other serial modes, these pins are high impedance outputs AGND 1 PIN 1 AVDD IDENTIFIER 2 MODE0 3 MODE1 4 D0/OB/2C 5 AD7641 WARP 6 TOP VIEW NORMAL 7 (Not to Scale) D1/A0 8 D2/ D4/DIVSCLK[0] 11 D5/DIVSCLK[1] 12 ...
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... When MODE[1: (serial mode), serial data output. In serial mode, this pin is used as the serial data output synchronized to SCLK. Conversion results are stored in an on-chip register. The AD7641 provides the conversion result, MSB first, from its internal shift register. The data format is determined by the logic level of OB/2C ...
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... CS is also used to gate the external clock in slave serial mode. 33 RESET DI Reset Input. When high, resets the AD7641. Current conversion, if any, is aborted. Falling edge of RESET enables the calibration mode indicated by pulsing BUSY high. Refer to the Digital Interface section. If not used, this pin can be tied to DGND. 34 ...
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... CNVST input to when the input signal is held for a conversion. Transient Response The time required for the AD7641 to achieve its rated accuracy after a full-scale step function is applied to its input. Reference Voltage Temperature Coefficient It is derived from the typical shift of output voltage at 25° ...
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... AD7641 TYPICAL PERFORMANCE CHARACTERISTICS 3.0 2.5 2.0 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 –3.0 0 65536 131072 CODE Figure 5. Integral Nonlinearity vs. Code 40000 34844 35000 31003 30000 25000 20000 15000 10938 10000 4730 5000 683 272 0 CODE IN HEX Figure 6. Histogram of 261,120 Conversions Input at the Code Center (External Reference) 2 ...
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... Figure 16. THD, Harmonics, and SFDR vs. Temperature Rev Page AD7641 f = 2MSPS 100.8kHz IN SNR = 93dB THD = –101dB SFDR = 101dB SINAD = 92.5dB 100 200 300 400 500 600 700 800 FREQUENCY (kHz) Figure 14 ...
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... AD7641 96.0 95.5 95.0 SNR 94.5 SINAD 94.0 93.5 93.0 –60 –50 –40 –30 INPUT LEVEL (dB) Figure 17. SNR and SINAD vs. Input Level (Referred to Full Scale –55 –35 – TEMPERATURE (°C) Figure 18. Power-Down Operating Currents vs. Temperature –20 –10 0 DVDD OVDD, 3.3V OVDD, 2.5V AVDD 65 85 105 125 Rev ...
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... ADC that does not exhibit any pipeline or latency, making it ideal for multiple multiplexed channel applications. The AD7641 can operate from a single 2.5 V supply and interface to either 2.5 V digital logic housed in a 48-lead LQFP package or a tiny 48-lead LFCSP package, ...
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... AD7641 TRANSFER FUNCTIONS Using the OB/ 2C digital input, except in 18-bit interface mode, the AD7641 offers two output codings: straight binary and twos complement. The LSB size with V = 2.048 × V REF 262,144, which is 15.623 μV. Refer to Figure 22 and Table 8 for the ideal transfer characteristic. ...
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... MHz, thereby reducing an undesirable aliasing effect and limiting the noise coming from the inputs. Because the input impedance of the AD7641 is very high, the AD7641 can be directly driven by a low impedance source without gain error. To further improve the noise filtering achieved by the AD7641 analog input circuit, an external 1-pole RC filter between the amplifier’ ...
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... ANALOG INPUT (UNIPOLAR 0V TO 2.048V) VOLTAGE REFERENCE INPUT The AD7641 allows the choice of either a very low temperature drift internal voltage reference or an external reference. Unlike many ADCs with internal references, the internal reference of the AD7641 provides excellent performance and Figure 23, can be used in almost all applications ...
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... V increase the range 2.8 V with an AVDD = 2.7 V. Temperature Sensor The TEMP pin measures the temperature of the AD7641. To improve the calibration accuracy over the temperature range, the output of the TEMP pin is applied to one of the inputs of the analog switch (such as, used to measure its own temperature ...
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... To reduce the operating digital supply currents even further, drive the digital inputs close to the power rails (that is, OVDD and OGND). CONVERSION CONTROL The AD7641 is controlled by the CNVST input. A falling edge on CNVST is all that is necessary to initiate a conversion. Detailed timing diagrams of the conversion process are shown in Figure 29 ...
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... INTERFACES DIGITAL INTERFACE The AD7641 has a versatile digital interface that can be set up as either a serial or a parallel interface with the host system. The serial interface is multiplexed on the parallel data bus. The AD7641 digital interface also accommodates 2 logic with either OVDD at 2 3.3 V. OVDD defines the logic high output voltage ...
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... Figure 34. 8-Bit and 16-Bit Parallel Interface SERIAL INTERFACE The AD7641 is configured to use the serial interface when MODE[1: The AD7641 outputs 18 bits of data, MSB first, on the SDOUT pin. This data is synchronized with the 18 clock pulses provided on the SCLK pin. The output data is valid on 4 both the rising and falling edge of the data clock ...
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... Figure 36. Master Serial Data Timing for Reading (Read Previous Conversion During Convert) INVSCLK = INVSYNC = 0 DIVSCLK[1: RDC/SDIN = D16 RDC/SDIN = 1 INVSCLK = INVSYNC = D16 Rev Page AD7641 ...
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... Figure 38 and Figure 39 show the detailed timing diagrams of these methods. While the AD7641 is performing a bit decision important that voltage transients be avoided on digital input/output pins or degradation of the conversion result could occur. This is particularly important during the second half of the conversion ...
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... SDOUT X D17 D16 t 16 Figure 39. Slave Serial Data Timing for Reading (Read Previous Conversion During Convert INVSCLK = D15 D1 D0 X15 INVSCLK = D15 D2 D0 Rev Page AD7641 20 X17 X16 Y17 Y16 ...
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... Figure 40 shows an interface diagram between the AD7641 and an SPI-equipped DSP, the ADSP-219x. To accommodate the slower speed of the DSP, the AD7641 acts as a slave device and data must be read after conversion. This mode also allows the daisy-chain feature. The convert command can be initiated in response to an internal timer interrupt ...
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... Digital and analog ground planes should be joined in only one place, preferably underneath the AD7641 close as possible to the AD7641. If the AD7641 system where multiple devices require analog-to-digital ground connections, the connections should still be made at one point only, a star ground point, established as close as possible to the AD7641 ...
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... AD7641BCPZ −40°C to +85°C 1 AD7641BCPZRL −40°C to +85°C 1 AD7641BSTZ −40°C to +85°C 1 AD7641BSTZRL −40°C to +85°C 2 EVAL-AD7641CB 3 EVAL-CONTROLBRD3 Pb-free part. 2 This board can be used as a standalone evaluation board or in conjunction with the EVAL-CONTROL BRD3 for evaluation/demonstration purposes. ...