AD7687 Analog Devices, AD7687 Datasheet
AD7687
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AD7687 Summary of contents
Page 1
... SDI input, to daisy-chain several ADCs on a single, 3-wire bus and provides an optional BUSY indicator compatible with 1 logic, using the separate supply VIO. The AD7687 is housed in a 10-lead MSOP or a 10-lead QFN (LFCSP) with operation specified from −40°C to +85°C. 49152 65535 One Technology Way, P ...
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... CS Mode 4-Wire with BUSY Indicator ................................... 21 Chain Mode, No BUSY Indicator ............................................ 22 Chain Mode with BUSY Indicator........................................... 23 Application Hints ........................................................................... 24 Layout .......................................................................................... 24 Evaluating the AD7687’s Performance.................................... 24 Outline Dimensions ....................................................................... 25 Ordering Guide .......................................................................... 26 Rev Page Data Sheet ...
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... IN REF kHz kHz kHz REF kHz −60 dB input IN REF kHz 2 REF Rev Page AD7687 Min Typ Max Unit 16 Bits − REF REF −0 0.1 V REF 0.1 V REF REF ...
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... AD7687 VDD = 2 5.5 V, VIO = 2 VDD, V Table 3. Parameter Conditions REFERENCE Voltage Range Load Current 250 kSPS, REF = 5 V SAMPLING DYNAMICS −3 dB Input Bandwidth Aperture Delay VDD = 5 V DIGITAL INPUTS Logic Levels DIGITAL OUTPUTS Data Format Pipeline Delay ...
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... ACQ t CYC t CNVH t SCK t SCK t SCKL t SCKH t HSDO t DSDO DIS t SSDICNV t HSDICNV t SSCKCNV t HSCKCNV t SSDISCK t HSDISCK t DSDOSDI Rev Page AD7687 Min Typ Max Unit 0.5 2.2 μs 1.8 μs 4 μ ...
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... AD7687 −40°C to +85°C, VDD = 2 4.5 V, VIO = 2 4 VDD + 0.3 V, whichever is the lowest, unless otherwise stated. See Figure 3 and Figure 4 for load conditions. Table 5. Parameter Conversion Time: CNV Rising Edge to Data Available Acquisition Time Time Between Conversions CNV Pulse Width ( CS Mode ) ...
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... TO SDO C L 50pF 500μ Figure 3. Load Circuit for Digital Interface Timing 70% VIO t DELAY VIO – 0.5V 2 0.8V OR 0.5V Figure 4. Voltage Levels for Timing Rev Page θ θ 2.96 200 44 1.4V t DELAY VIO – 0.5V 2 0.8V OR 0.5V AD7687 Unit °C/W °C/W ...
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... AI = Analog Input Digital Input Digital Output Power, and N/A = not applicable. VIO SDI SCK SDO CNV Rev Page Data Sheet REF 1 10 VIO VDD 2 9 SDI AD7687 IN SCK TOP VIEW (Not to Scale) IN– SDO GND 5 6 CNV NOTES 1. FOR THE LFCSP PACKAGE ONLY, THE EXPOSED PADDLE MUST BE CONNECTED TO GND ...
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... CNV input and when the input signal is held for a conversion. Transient Response It is the time required for the ADC to accurately acquire its input after a full-scale step function was applied. Rev Page AD7687 − 1.76)/6.02 ...
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... AD7687 TYPICAL PERFORMANCE CHARACTERISTICS 1.5 POSITIVE INL = +0.32LSB NEGATIVE INL = –0.41LSB 1.0 0.5 0 –0.5 –1.0 –1.5 0 16384 32768 CODE Figure 7. Integral Nonlinearity vs. Code 300000 258680 250000 200000 150000 100000 50000 0 0 1049 CODE IN HEX Figure 8. Histogram Input at the Code Center 0 – ...
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... THD SFDR 2.3 2.7 3.1 3.5 3.9 4.3 REFERENCE VOLTAGE (V) Figure 16. THD, SFDR vs. Reference Voltage VREF = 2.5V, –1dB VREF = 5V, –1dB VREF = 2.5V, –10dB VREF = 5V, –10dB 0 50 100 FREQUENCY (kHz) Figure 17. THD vs. Frequency VREF = 5V VREF = 2.5V –55 –35 – TEMPERATURE ( ° C) Figure 18. THD vs. Temperature AD7687 4.7 5.1 5.5 150 200 85 105 125 ...
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... AD7687 100 –10 –8 –6 –4 INPUT LEVEL (dB) Figure 19. SNR vs. Input Level 1000 f = 100kSPS S 750 500 250 0 2.3 2.7 3.1 3.5 3.9 SUPPLY (V) Figure 20. Operating Currents vs. Supply 1000 750 500 250 0 –55 –35 – TEMPERATURE (°C) Figure 21. Power-Down Currents vs. Temperature ...
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... The AD7687 is specified from 2 5.5 V and can be interfaced to any of the 1 digital logic family housed in a 10-lead MSOP or a tiny 10-lead QFN (LFCSP) that combines space savings and allows flexible configurations ...
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... AD7687 Transfer Functions The ideal transfer characteristic for the AD7687 is shown in Figure 26 and Table 9. 011...111 011...110 011...101 100...010 100...001 100...000 –FSR –FSR + 1 LSB –FSR + 0.5 LSB +FSR – 1.5 LSB ANALOG INPUT Figure 26. ADC Ideal Transfer Function Table 9 ...
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... When the source impedance of the driving circuit is low, the AD7687 can be driven directly. Large source impedances significantly affect the ac performance, especially total harmonic distortion (THD). The dc performances are less sensitive to the input impedance ...
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... REF and GND pins. POWER SUPPLY The AD7687 is specified over a wide operating range of 2 5.5 V. Unlike other low voltage converters, it has a low enough noise to design a 16-bit resolution system with low supply and respectable performance. It uses two power supply pins: a core supply VDD and a digital input/output interface supply VIO ...
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... OPTIONAL REFERENCE BUFFER AND FILTER. DIGITAL INTERFACE Though the AD7687 has a reduced number of pins, it offers flexibility in its serial interface modes. The AD7687, when in CS mode, is compatible with SPI, QSPI, 1000 10000 digital hosts, and DSPs, for example, Blackfin® ADSP-BF53x or ADSP-219x ...
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... AD7687 CS MODE 3-WIRE, NO BUSY INDICATOR This mode is usually used when a single AD7687 is connected to an SPI-compatible digital host. The connection diagram is shown in Figure 35 and the corresponding timing is given in Figure 36. With SDI tied to VIO, a rising edge on CNV initiates a conversion, selects the CS mode, and forces SDO to high impedance ...
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... Data Sheet CS MODE 3-WIRE WITH BUSY INDICATOR This mode is usually used when a single AD7687 is connected to an SPI-compatible digital host having an interrupt input. The connection diagram is shown in Figure 37 and the corresponding timing is given in Figure 38. With SDI tied to VIO, a rising edge on CNV initiates a conversion, selects the CS mode, and forces SDO to high impedance ...
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... Although the rising edge can be used to capture the data, a digital host using the SCK falling edge allows a faster reading rate provided it has an acceptable hold time. After the 16th SCK falling edge, or when SDI goes high, whichever is earlier, SDO returns to high impedance and another AD7687 can be read. CNV AD7687 SDO ...
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... Data Sheet CS MODE 4-WIRE WITH BUSY INDICATOR This mode is usually used when a single AD7687 is connected to an SPI-compatible digital host, which has an interrupt input, and it is desired to keep CNV, which is used to sample the analog input, independent of the signal used to select the data reading ...
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... AD7687 CHAIN MODE, NO BUSY INDICATOR This mode can be used to daisy chain multiple AD7687s wire serial interface. This feature is useful for reducing component count and wiring connections, for example, in isolated multiconverter applications or for systems with a limited interfacing capacity. Data readback is analogous to clocking a shift register ...
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... SCK falling edge allows a faster reading rate and consequently more AD7687s in the chain, provided the digital host has an acceptable hold time. For instance, with digital host setup time and 3 V interface eight AD7687s running at a conversion rate of 220 kSPS can be daisy-chained to a single 3-wire port. ...
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... The pinout of the AD7687, with all its analog signals on the left side and all its digital signals on the right side, eases this task. Avoid running digital lines under the device because these couple noise onto the die, unless a ground plane under the AD7687 is used as a shield ...
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... Figure 50. 10-Lead Lead Frame Chip Scale Package [QFN (LFCSP_WD × Body, Very Very Thin, Dual Lead (CP-10-9) Dimensions shown in millimeters Rev Page 0.70 0.55 0.40 2.48 2.38 2.23 0.50 BSC 10 1.74 EXPOSED PAD 1.64 1.49 1 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. AD7687 ...
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... Z = RoHS Compliant Part, # denotes RoHS compliant product, may be top or bottom marked. 2 The EVAL-AD7687CB can be used as a standalone evaluation board or in conjunction with the EVAL-CONTROL BRDx for evaluation/demonstration purposes. 3 The EVAL-CONTROL BRD2 and EVAL-CONTROL BRD3 allow control and communicate with all Analog Devices evaluation boards ending in the CB designators. ...
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... Data Sheet NOTES Rev Page AD7687 ...
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... AD7687 NOTES ©2005–2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D02972-0-8/11(B) Rev Page Data Sheet ...