AD7891 Analog Devices, AD7891 Datasheet
AD7891
Specifications of AD7891
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AD7891 Summary of contents
Page 1
... The part operates from a single 5 V supply and accepts a variety of analog input ranges across two models, the AD7891-1 (± and ± and the AD7891 +2 and ± 2.5 V). The AD7891 provides the option of either a parallel or serial interface structure determined by the MODE pin ...
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... Unipolar Offset Error Match 4 Negative Full-Scale Error 4, 5 Negative Full-Scale Error Match Bipolar Zero Error 5 Bipolar Zero Error Match ANALOG INPUTS AD7891-1 Input Voltage Range AD7891-1 V Input Resistance INXA AD7891-1 V Input Resistance INXA AD7891-2 Input Voltage Range AD7891-2 V Input Resistance INXA ...
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... AGND . . . . . . . . . . . . . . . . . . . . . . . . . –0 DGND . . . . . . . . . . . . . . . . . . . . . . . . . –0 Analog Input Voltage to AGND AD7891 ± AD7891 –5 V, +10 V Reference Input Voltage to AGND . . . . –0 Digital Input Voltage to DGND . . . . . . –0 Digital Output Voltage to DGND . . . . . –0 Operating Temperature Range Commercial (A, B Versions –40∞C to +85∞C Automotive (Y Version – ...
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... AD7891 TIMING CHARACTERISTICS Parameter Versions t 1.6 CONV Parallel Interface Serial Interface ...
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... +2.5 V, ± 2.5 V AD7891AP +2.5 V, ± 2.5 V AD7891AP-2REEL +2.5 V, ± 2.5 V AD7891BS +2.5 V, ± 2.5 V AD7891BP +2.5 V, ± 2.5 V AD7891BP-2REEL +2.5 V, ± 2.5 V AD7891YS +2.5 V, ± 2.5 V AD7891YS-2REEL ...
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... Interface Mode. Control input that determines the interface mode for the part. With this pin at a logic low, the AD7891 is in its serial interface mode; with this pin at a logic high, the device is in its parallel interface mode. –6– ...
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... Data I/O Lines There are 12 data input/output lines on the AD7891. When the part is configured for parallel mode (MODE = 1), the output data from the part is provided at these 12 pins during a read operation. For a write operation in parallel mode, these lines provide access to the part’s control register. ...
Page 8
... TEST CONTROL REGISTER The control register for the AD7891 contains six bits of information as described below. These six bits can be written to the control register either in a parallel mode write operation or via a serial mode write operation. The default (power-on) condition of all bits in the control register is 0. Six serial clock pulses must be provided to the part in order to write data to the control register. If TFS returns high before six serial clock cycles, no data transfer takes place to the control register and the write cycle has to be restarted to write data to the control register ...
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... 01. . .111) from the ideal 4 ¥ REF IN – 3/2 LSB (AD7891-1 V ± range), 2 ¥ REF IN – 3/2 LSB (AD7891-1 ± range REF IN – 3/2 LSB (AD7891-2, ± 2.5 V range), after the , bipolar zero error has been adjusted out. Positive Full-Scale Error (AD7891- and 2.5 V) This is the deviation of the last code transition (11. . .110 to 11. . .111) from the ideal 2 ¥ ...
Page 10
... The conversion clock for the part is internally generated and conversion time for the AD7891 is 1.6 ms from the rising edge of the hardware CONVST signal. The track/hold acquisition time for the AD7891-1 is 600 ns, while the track/hold acquisition time for the AD7891-2 is 400 ns ...
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... Write Operation Figure 4 shows a write operation to the control register of the AD7891. The TFS input goes low to indicate to the part that a serial write is about to occur. The AD7891 control register requires only six bits of data. These are loaded on the first six clock cycles of the serial clock with data on all subsequent clock cycles being ignored ...
Page 12
... If the application requires a reference with a tighter tolerance or if the AD7891 needs to be used with a system reference, an external reference can be connected to the REF OUT/REF IN pin. The external reference overdrives the internal reference and thus provides the reference source for the ADC ...
Page 13
... LSB = FSR/4096 = +4.88 mV (± range), +2.44 mV (± range), and +1.22 mV (± 2.5 V range), with REF IN = +2.5 V. ± range, ± range, or ± 2.5 V range. 4 Table II. Ideal Code Transition Table for the AD7891- and 2.5 V Ranges Analog Input Input Voltage 2 ...
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... AD7891, the MOSI output drives DATA IN of the AD7891, and the MISO input receives data from DATA OUT of the AD7891. Ports PC6 and PC7 of the 68HC11 drive the TFS and RFS lines of the AD7891, respectively. For correct operation of this interface, the 68HC11 should be configured such that its CPOL bit and its CPHA bit ...
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... AD7891. When reading from the part, the SPORT must be set up with a serial word length of 16 bits. When writing to the AD7891, a serial word length of 6 bits or more can be used. Other setups for the serial interface on the ADSP-21xx internal SCLK use alternate framing mode and active low framing signal ...
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... AD7891 PARALLEL INTERFACING The parallel port on the AD7891 allows the device to be interfaced to microprocessors or DSP processors as a memory mapped or I/O mapped device. The CS and RD inputs are common to all memory peripheral interfacing. Typical interfaces to different processors are shown in Figures 12 to 15. In all the interfaces shown, an external timer controls the CONVST input of the AD7891 and the EOC output interrupts the host DSP ...
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... AGND to DGND connection, then the ground planes should be connected at the AGND and DGND pins of the AD7891. If the AD7891 system where multiple devices require an AGND to DGND connection, the connection should still be made at one point only, a star ground point established as close as possible to the AD7891 ...
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... V input range and the data was read from the part in parallel mode after conversion. Similar results have been found with the AD7891-1 on the ± range and on all input ranges of the AD7891-2. The same performance is achieved in serial mode, again with the data read from the AD7891-1 after conversion ...
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... The AD7891-1 plot only goes to 100 kHz as a ± sine wave of sufficient quality was unavailable at higher frequencies. Figure 20 shows that the AD7891-1 converts an input sine wave of 100 kHz to an effective number of bits of 11 which equates to a signal-to-(noise + distortion) level of 68.02 dBs. The AD7891-2 converts an input sine wave of 200 kHz to an effective number of bits of 11 ...
Page 20
... Changes to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Changes to PIN FUNCTION DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Changes to PARALLEL INTERFACE MODE FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Changes to SERIAL INTERFACE MODE FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Changes to CONTROL REGISTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Changes to AD7891 to 8X51 Serial Interface section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Changes to Figure Changes to Figure Changes to Power Supply Bypassing and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Changes to Figure Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 01/02— ...