EVAL-AD7944EBZ Analog Devices Inc, EVAL-AD7944EBZ Datasheet
EVAL-AD7944EBZ
Specifications of EVAL-AD7944EBZ
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EVAL-AD7944EBZ Summary of contents
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FEATURES 14-bit resolution with no missing codes Throughput: 2.5 MSPS (TURBO high), 2.0 MSPS (TURBO low) Low power dissipation 15 2.5 MSPS, with external reference 2.5 MSPS, with internal reference INL: ±0.25 LSB typical, ±1.0 ...
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... CS Mode, 3-Wire Without Busy Indicator ............................. 19 CS Mode, 3-Wire with Busy Indicator .................................... 20 CS Mode, 4-Wire Without Busy Indicator ............................. 21 CS Mode, 4-Wire with Busy Indicator .................................... 22 Chain Mode Without Busy Indicator ...................................... 23 Chain Mode with Busy Indicator ............................................. 24 Applications Information .............................................................. 25 Layout .......................................................................................... 25 Evaluating AD7944 Performance ............................................. 25 Outline Dimensions ....................................................................... 27 Ordering Guide .......................................................................... 27 Rev Page ...
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SPECIFICATIONS AVDD = DVDD = 2.5 V, BVDD = 5 V, VIO = 1 2 Table 2. Parameter RESOLUTION ANALOG INPUT Voltage Range Absolute Input Voltage Leakage Current at 25°C Input Impedance ACCURACY No Missing Codes ...
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AD7944 Table 3. Parameter INTERNAL REFERENCE Output Voltage Temperature Drift Line Regulation Turn-On Settling Time REFIN Output Voltage REFIN Output Resistance EXTERNAL REFERENCE Voltage Range Current Drain REFERENCE BUFFER REFIN Input Voltage REFIN Input Current DIGITAL INPUTS Logic Levels V ...
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TIMING SPECIFICATIONS AVDD = DVDD = 2.5 V, BVDD = 5 V, VIO = 1 2 Table 4. Parameter Conversion Time: CNV Rising Edge to Data Available Acquisition Time Time Between Conversions CNV Pulse Width Data ...
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AD7944 ABSOLUTE MAXIMUM RATINGS Table 5. Parameter Analog Inputs IN+, IN− to GND 1 Supply Voltage REF, BVDD to GND, REFGND AVDD, DVDD, VIO to GND AVDD, DVDD to VIO Digital Inputs to GND Digital Outputs to GND Storage Temperature ...
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PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Table 6. Pin Function Descriptions Pin No. Mnemonic Type Description REF AI Reference Output/Input Voltage. When PDREF is low, the internal reference and buffer are enabled, producing 4.096 V on this pin. ...
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AD7944 Pin No. Mnemonic Type 1 Description 19 BVDD P Reference Buffer Power. Nominally at 5 external reference buffer is used to achieve the maximum SNR performance with reference, the reference buffer must be ...
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TYPICAL PERFORMANCE CHARACTERISTICS AVDD = DVDD = VIO = 2.5 V, BVDD = 5 1.0 POSITIVE INL = +0.12 LSB NEGATIVE INL = –0.20 LSB 0.8 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 –0.8 –1.0 0 4096 8192 ...
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AD7944 0 –20 –40 –60 –80 –100 –120 –140 –160 –180 0 250 500 750 FREQUENCY (kHz) Figure 11. FFT Plot (External Reference) 84 SNR ENOB 2.5 3.0 3.5 4.0 REFERENCE VOLTAGE (V) Figure ...
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INPUT LEVEL (dBFS) Figure 17. SNR vs. Input Level 2.0 1.8 I AVDD 1.6 I DVDD 1.4 I VIO 1.2 1.0 ...
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AD7944 TERMINOLOGY Aperture Delay Aperture delay is the measure of the acquisition performance the time between the rising edge of the CNV input and when the input signal is held for a conversion. Differential Nonlinearity Error (DNL) In ...
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THEORY OF OPERATION IN+ 8192C REF REFGND 8192C IN– CIRCUIT INFORMATION The AD7944 is a fast, low power, single-supply, precise, 14-bit ADC using a successive approximation architecture. The AD7944 features different modes to optimize performance according to the application. In ...
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AD7944 Transfer Functions The ideal transfer characteristic for the AD7944 is shown in Figure 22 and Table 7. 111 ... 111 111 ... 110 111 ... 101 000 ... 010 000 ... 001 000 ... 000 –FSR –FSR + 1 ...
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ANALOG INPUTS Figure 24 shows an equivalent circuit of the analog input structure of the AD7944. The two diodes, D1 and D2, provide ESD protection for the analog inputs, IN+ and IN−. Care must be taken to ensure that the ...
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AD7944 VOLTAGE REFERENCE INPUT The AD7944 allows the choice of a very low temperature drift internal voltage reference, an external reference external buffered reference. The internal reference of the AD7944 provides excellent performance and can be used in ...
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DIGITAL INTERFACE Although the AD7944 has a reduced number of pins, it offers flexibility in its serial interface modes mode, the AD7944 is compatible with SPI, MICROWIRE™, QSPI™, and digital hosts mode, the AD7944 can use ...
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AD7944 DATA READING OPTIONS There are three different data reading options for the AD7944. There is the option to read during conversion, to split the read across acquisition and conversion (see Figure 28 and Figure 29), and, in normal mode, ...
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CS MODE, 3-WIRE WITHOUT BUSY INDICATOR This mode is usually used when a single AD7944 is connected to an SPI-compatible digital host. The connection diagram is shown in Figure 26, and the corresponding timing is given in Figure 27. With ...
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AD7944 CS MODE, 3-WIRE WITH BUSY INDICATOR This mode is usually used when a single AD7944 is connected to an SPI-compatible digital host that has an interrupt input available only in normal conversion mode (TURBO low). The connection ...
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CS MODE, 4-WIRE WITHOUT BUSY INDICATOR This mode is usually used when multiple AD7944 devices are connected to an SPI-compatible digital host. A connection dia- gram example using two AD7944 devices is shown in Figure 30, and the corresponding timing ...
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AD7944 CS MODE, 4-WIRE WITH BUSY INDICATOR This mode is usually used when a single AD7944 is connected to an SPI-compatible digital host with an interrupt input and when it is desired to keep CNV, which is used to sample ...
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CHAIN MODE WITHOUT BUSY INDICATOR This mode can be used to daisy-chain multiple AD7944 devices on a 3-wire serial interface available only in normal conversion mode (TURBO is low). This feature is useful for reducing com- ponent count ...
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AD7944 CHAIN MODE WITH BUSY INDICATOR This mode can be used to daisy-chain multiple AD7944 devices on a 3-wire serial interface while providing a busy indicator available only in normal conversion mode (TURBO low). This feature is useful ...
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... EVALUATING AD7944 PERFORMANCE Other recommended layouts for the AD7944 are outlined in the documentation for the AD7944 evaluation board (EVAL-AD7944EBZ). The evaluation board package includes a fully assembled and tested evaluation board, documentation, and software for controlling the board from a PC via the EVAL-CED1Z board ...
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AD7944 REF REF GND GND 5V EXTERNAL REFERENCE (ADR435 OR ADR445) REF REF C REF GND GND BVDD REF GND Figure 38. Example Layout of the AD7944 (Top Layer) BVDD AVDD C BVDD REF ...
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... EVAL-AD7944EBZ EVAL-CED1Z RoHS Compliant Part. 2 The EVAL-AD7944EBZ can be used as a standalone evaluation board or in conjunction with the EVAL-CED1Z for evaluation/demonstration purposes. 3 The EVAL-CED1Z allows control and communicate with all Analog Devices evaluation boards ending in the EB designator. 0.60 MAX 4.00 BSC SQ ...
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AD7944 NOTES ©2009-2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D04658-0-8/10(A) Rev Page ...