AD7788 Analog Devices, AD7788 Datasheet
AD7788
Specifications of AD7788
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AD7788 Summary of contents
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... The AD7789 contains a low noise, 24-bit, ∑-Δ ADC with one differential input. The AD7788 is a 16-bit version of the AD7789. The devices operate from an internal clock. Therefore, the user does not have to supply a clock source to the devices. ...
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... AD7788/AD7789 TABLE OF CONTENTS Features .............................................................................................. 1 Interface ............................................................................................. 1 Applications....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 AD7789 .......................................................................................... 3 AD7788 .......................................................................................... 4 AD7788/AD7789.......................................................................... 5 Timing Characteristics ................................................................ 6 Timing Diagrams.......................................................................... 7 Absolute Maximum Ratings............................................................ 8 ESD Caution.................................................................................. 8 Pin Configuration and Function Descriptions............................. 9 Typical Performance Characteristics ........................................... 10 On-Chip Registers .......................................................................... 11 REVISION HISTORY 3/06—Rev Rev. B Changes to Ordering Guide .......................................................... 19 11/04— ...
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... Rev Page AD7788/AD7789 unless otherwise noted. MIN MAX Test Conditions/Comments 100 dB typ, AIN = 1 V REFIN = REFIN(+) − REFIN(−) Input current varies with input voltage 50 Hz ± ± ...
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... Temperature range: B grade: 40°C to +105°C; A grade: 2 Specification is not production tested but is supported by characterization data at initial product release. 3 Full-scale error applies to both positive and negative full scale and applies at the factory calibration conditions (V AD7788 A, AD7788B Unit 16.6 Hz nom 16 Bits min 16 Bits p-p 1.5 μ ...
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... DD SOURCE V max 100 μA DD SINK V min 200 μA DD SOURCE V max 1 SINK μA max pF typ V min/max AD7789, AD7788 B grade V min/max AD7788 A grade μA max 65 μA typ 3 μA max 73 μA typ 5. μA max ...
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... RDY returns high after a read of the ADC. In single-conversion mode and continuous-conversion mode, the same data can be read again, if required, while RDY is high, although care should be taken to ensure that subsequent reads do not occur close to the next output update. In continuous read mode, the digital word can be read only once 5.25 V (AD7788A); GND = 0 V; REFIN(+) = 2.5 V; REFIN(−) = GND unless otherwise noted. ...
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... MSB SCLK ( INPUT OUTPUT Figure 3. Read Cycle Timing Diagram CS ( SCLK ( DIN (I) MSB I = INPUT OUTPUT Figure 4. Write Cycle Timing Diagram Rev Page AD7788/AD7789 = 5V 3V LSB LSB ...
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... AD7788/AD7789 ABSOLUTE MAXIMUM RATINGS T = 25°C, unless otherwise noted. A Table 5. Parameter V to GND DD Analog Input Voltage to GND Reference Input Voltage to GND Total AIN/REFIN Current (Indefinite) Digital Input Voltage to GND Digital Output Voltage to GND Operating Temperature Range B Grade A Grade Storage Temperature Range ...
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... V 3 TOP VIEW 8 DD (Not to Scale) AIN(–) GND 4 7 REFIN(+) REFIN(– Figure 5. Pin Configuration REFIN(−)) is 2.5 V, but the part functions with a reference from 0 − Rev Page AD7788/AD7789 and GND + 0.1 V. The nominal reference − 0 ...
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... Rev Page 3V 2.048V, DD REF T = 25°C, RMS NOISE = 1.25µ 200 400 600 800 READ NO. Figure 8. AD7789 Noise Plot UPDATE RATE = 16.6Hz T = 25° 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 V (V) REF Figure 9. AD7788/AD7789 Noise vs. V REF 1000 4.5 5.0 ...
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... CR denoting the bits are in the communications register. CR7 denotes the first bit of the data stream. The number in brackets indicates the power-on/reset default status of that bit. CR4 CR3 CR2 RS0[0] R/W[0] CREAD[0] Rev Page AD7788/AD7789 CR1 CR0 CH1[0] CH0[0] ...
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... This bit is set automatically. SR2 WL AD7788/AD7789 Identifier. This bit is cleared automatically if the device is an AD7788 and it is set automatically if the device is an AD7789. This bit is used to distinguish between the AD7788 and AD7789. SR1 to SR0 CH1 to CH0 These bits indicate which channel is being converted by the ADC. ...
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... Power-down mode DATA REGISTER (RS1, RS0 = 1, 1; Power-On/Reset = 0x0000 for the AD7788 and 0x000000 for the AD7789) The conversion result from the ADC is stored in this data register. This is a read only register. On completion of a read operation from this register, the RDY bit/pin is set. ...
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... Typically, the devices have an rms noise of 1.5 μV rms that corresponds to a peak-to-peak resolution of 16 bits for the AD7788 and 19 bits (equivalent to an effective resolution of 21.5 bits) for the AD7789. These numbers are for the bipolar input range with a reference of 2.5 V. The noise was measured with a differential input voltage ...
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... The serial interface can be reset by writing a series the DIN input Logic 1 is written to the AD7788/AD7789 for at least 32 serial clock cycles, the serial interface is reset. This ensures that the interface can be reset to a known state if the interface gets lost due to a software error or a glitch in the system ...
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... If the data-word has not read the conversion before the completion of the next conversion insufficient serial clocks are applied to the AD7788/AD7789 to read the word, the serial output register is reset when the next conversion is complete and the new conversion is placed in the output serial register. ...
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... ADC input. Table 13 shows the allowable external resistance/capacitance values such that no gain error at the 16-bit level is introduced (AD7788). Table 14 shows the allowable external resistance/capacitance values such that no gain error at the 20-bit level is introduced (AD7789). ...
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... The AD7788/AD7789 ground plane should be allowed to run under the devices to prevent noise coupling. The power supply lines to the AD7788/AD7789 should use as wide a trace as possible to provide low impedance paths and reduce the effects of glitches on the power supply line. Fast switching signals, such ...
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... AD7788BRMZ −40°C to +105°C 1 AD7788BRMZ-REEL −40°C to +105°C AD7788ARM −40°C to +85°C AD7788ARM-REEL −40°C to +85°C 1 AD7788ARMZ −40°C to +85°C AD7789BRM −40°C to +105°C AD7789BRM-REEL −40°C to +105°C 1 AD7789BRMZ −40°C to +105°C 1 AD7789BRMZ-REEL − ...
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... AD7788/AD7789 NOTES ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03539-0-3/06(B) Rev Page ...