AD7621 Analog Devices, AD7621 Datasheet
AD7621
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AD7621 Summary of contents
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... Internal Reference. The AD7621 has a 2.048 V internal reference with a typical drift of ±7 ppm/°C. 4. Single-Supply Operation. The AD7621 operates from a 2.5 V single supply and typically dissipates 65 mW. In impulse mode, its power dissipation decreases with th 5. Serial or Parallel Interface. Versatile parallel (16- or 8-bit bus) or 2-wire serial interf arrangement compatible with 2 ...
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... Revision 0: Initial Version Voltage Reference Input ............................................................ 18 Power Supply............................................................................... 19 Power Dissipation vs. Throughput .......................................... 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 ...................................................................................... 27 Layout .......................................................................................... 27 Evaluating the AD7621 Performance ...................................... 27 Outline Dimensions ....................................................................... 28 Ordering Guide .......................................................................... 29 Rev Page ...
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... MSPS 4 ±1 +2 LSB Bits +2 LSB 0.69 LSB 0.82 LSB +30 LSB ±1 ppm/°C +0. FSR ±2 ppm/°C ±3 LSB 6 90 89.2 dB 103 dB 101 dB –102 dB −100 dB 89 MHz rms 50 ns 2.048 2.058 V ±7 ppm/°C ±15 ppm/V AD7621 ...
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... AD7621 Parameter Turn-On Settling Time REFBUFIN Output Voltage REFBUFIN Output Resistance EXTERNAL REFERENCE Voltage Range Current Drain REFERENCE BUFFER REFBUFIN Input Voltage Range TEMPERATURE PIN Voltage Output Temperature Sensitivity Output Resistance DIGITAL INPUTS Logic Levels DIGITAL OUTPUTS ...
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... MAX Min Typ Max 333/500/800 23 283/430/560 1 10 283/430/560 50/70/ 600 283/430/560 12/137/263 0 See Table 4 275/400/500 13 AD7621 Unit ...
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... AD7621 Parameter 5 SLAVE SERIAL INTERFACE MODES (Refer to Figure 40 and Figure 41) External SCLK Setup Time External SCLK Active Edge to SDOUT Delay SDIN Setup Time SDIN Hold Time External SCLK Period External SCLK High External SCLK Low 1 See the Conversion Control section. 2 All timings for wideband warp mode are the same as warp mode. ...
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... ESD CAUTION = 91°C/ 26°C/W. JA Rev Page AD7621 ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to ...
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... When EXT/INT = high: slave mode. The output data is synchronized to an external clock signal, gated by CS, connected to the SCLK input AGND 1 PIN 1 AVDD 2 IDENTIFIER NC 3 BYTESWAP 4 OB/2C 5 AD7621 WARP 6 TOP VIEW IMPULSE 7 (Not to Scale) SER/PAR D2/DIVSCLK[0] 11 D3/DIVSCLK[1] ...
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... When SER/PAR = high, 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 AD7621 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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... RESET DI Reset Input. When high, reset the AD7621. 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 AD7621 to achieve its rated accuracy after a full-scale step function is applied to its input. Reference Voltage Temperature Coefficient Reference voltage temperature coefficient is derived from the typical shift of output voltage at 25° ...
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... AD7621 TYPICAL PERFORMANCE CHARACTERISTICS 2.0 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 0 16384 32768 CODE Figure 5. Integral Nonlinearity vs. Code 160000 149969 140000 120000 100000 80000 54791 60000 51847 40000 20000 2080 7FFC 7FFD 7FFE 7FFF 8000 8001 CODE IN HEX Figure 6. Histogram of 261,120 Conversions Input at the Code Center (External Reference) 2 ...
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... TEMPERATURE ( ° C) Figure 15. SNR, SINAD, and ENOB vs. Temperature SFDR THD THIRD HARMONIC SECOND HARMONIC –35 – TEMPERATURE ( ° C) Figure 16. THD, Harmonics, and SFDR vs. Temperature AD7621 16.0 15.5 15.0 14.5 14.0 125 110 105 100 105 125 ...
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... AD7621 91.0 SNR 90.5 SINAD 90.0 89.5 –60 –50 –40 –30 INPUT LEVEL (dB) Figure 17. SNR and SINAD vs. Input Level (Referred to Full Scale AVDD –55 –35 – TEMPERATURE ( ° C) Figure 18. Power-Down Operating Currents vs. Temperature 100k –20 –10 0 280 270 260 OVDD, 3 ...
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... ADC that does not exhibit any pipeline or latency, making it ideal for multiple multiplexed channel applications. The AD7621 can be operated from a single 2.5 V supply and be interfaced to either 2.5 V digital logic housed in 48-lead LQFP or tiny LFCSP packages that combine space savings with flexibility, allowing the AD7621 to be configured as either a serial or parallel interface ...
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... AD7621 TRANSFER FUNCTIONS Using the OB/ 2C digital input, the AD7621 offers two output codings: straight binary and twos complement. The LSB size with V = 2.048 × V /65536, which is 62.5 μV. Refer to REF REF Figure 22 and Table 7 for the ideal transfer characteristic. 111...111 111 ...
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... MHz, thereby reducing an undesirable aliasing effect while limiting noise from the inputs. Since the input impedance of the AD7621 is very high, the AD7621 can be directly driven by a low impedance source without gain error. To further improve the noise filtering achieved by the AD7621 analog input circuit, an external, one- pole RC filter between the amplifier’ ...
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... N VOLTAGE REFERENCE INPUT The AD7621 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 with a noise gain reference of the AD7621 provides excellent performance and can be used in almost all applications. ...
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... Figure 28. ANALOG INPUT (UNIPOLAR) POWER SUPPLY The AD7621 uses three sets of power supply pins: an analog 2.5 V supply AVDD, a digital 2.5 V core supply DVDD, and a digital input/output interface supply OVDD. The OVDD supply allows direct interface with any logic working between 2.3 V and 5. reduce the number of supplies needed, the digital core (DVDD) can be supplied through a simple RC filter from the analog supply as shown in Figure 23 ...
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... SAMPLING RATE (SPS) Figure 30. Power Dissipation vs. Sample Rate CONVERSION CONTROL The AD7621 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 31. Once initiated, it cannot be restarted or aborted, even by the power-down input, PD, until the conversion is complete ...
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... RD is generally used to enable the conversion result on the data bus. RESET The RESET input is used to reset the AD7621 and generate a fast initialization. A rising edge on RESET aborts the current conversion (if any) and tristates the data bus. The falling edge of RESET clears the data bus and engages the initialization process indicated by pulsing BUSY high ...
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... Figure 36. 8-Bit and 16-Bit Parallel Interface SERIAL INTERFACE The AD7621 is configured to use the serial interface when SER/ PAR is held high. The AD7621 outputs 16 bits of data, MSB first, on the SDOUT pin. This data is synchronized with the 16 clock pulses provided on the SCLK pin. The output data 4 is valid on both the rising and falling edge of the data clock ...
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... Figure 38. Master Serial Data Timing for Reading (Read Previous Conversion During Convert) RDC/SDIN = 0 INVSCLK = INVSYNC = D15 D14 t 23 RDC/SDIN = 1 INVSCLK = INVSYNC = D14 Rev Page AD7621 ...
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... Figure 40 and Figure 41 show the detailed timing diagrams of these methods. While the AD7621 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 ...
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... Figure 41. Slave Serial Data Timing for Reading (Read Previous Conversion During Convert) EXT/INT = 1 INVSCLK = D14 D13 X14 X13 EXT/INT = 1 INVSCLK = D14 D13 Rev Page X15 X14 Y15 Y14 AD7621 ...
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... Figure 42 shows an interface diagram between the AD7621 and an SPI-equipped DSP, ADSP-219x. To accommodate the slower speed of the DSP, the AD7621 acts as a slave device and data must be read after conversion. This mode also allows the daisy- chain feature. The convert command could 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 AD7621 close as possible to the AD7621. If the AD7621 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 AD7621 ...
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... AD7621 OUTLINE DIMENSIONS 1.45 1.40 1.35 0.15 0.05 VIEW A ROTATED 90° CCW 7.00 BSC SQ PIN 1 INDICATOR TOP VIEW 1.00 12° MAX 0.85 0.80 SEATING PLANE 0.75 1.60 0.60 MAX 0.45 0.20 0.09 7° 3.5° 12 0° SEATING 0.08 MAX PLANE VIEW A 0.50 COPLANARITY BSC LEAD PITCH COMPLIANT TO JEDEC STANDARDS MS-026BBC Figure 43. 48-Lead Low Profile Quad Flatpack (LQFP) [ST-48] Dimensions shown in millimeters ...
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... AD7621ACPZ −40°C to +85°C 1 AD7621ACPZRL −40°C to +85°C AD7621AST −40°C to +85°C AD7621ASTRL −40°C to +85°C 1 AD7621ASTZ −40°C to +85°C AD7621ASTZRL 1 −40°C to +85°C 2 EVAL-AD7621CB 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. ...
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... AD7621 NOTES Rev Page ...
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... NOTES Rev Page AD7621 ...
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... AD7621 NOTES ©2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D04565–0–5/05(0) Rev Page ...