參數(shù)資料
型號(hào): AD5744
廠商: Analog Devices, Inc.
英文描述: Complete, Quad, 14/16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC
中文描述: 完整,四路,14/16-Bit,高精度,串行輸入,雙極性電壓輸出DAC
文件頁(yè)數(shù): 17/27頁(yè)
文件大?。?/td> 243K
代理商: AD5744
Preliminary Technical Data
Rev. PrA 15-Nov-04| Page 17 of 27
68HC11*
MISO
SYNC
SDIN
SCLK
MOSI
SCK
PC7
PC6
LDAC
SDO
SYNC
SCLK
LDAC
SDO
SYNC
SCLK
LDAC
SDO
SDIN
SDIN
*ADDITIONAL PINS OMITTED FOR CLARITY
AD5744/64*
AD5744/64*
AD5744/64*
R
Figure 8. Daisy chaining the AD5744/64
Daisy-Chain Operation
For systems that contain several devices, the SDO pin may be
used to daisy-chain several devices together. This daisy-chain
mode can be useful in system diagnostics and in reducing the
number of serial interface lines. The first falling edge of SYNC
starts the write cycle. The SCLK is continuously applied to the
input shift register when SYNC is low. If more than 24 clock
pulses are applied, the data ripples out of the shift register and
appears on the SDO line. This data is clocked out on the rising
edge of SCLK and is valid on the falling edge. By connecting the
SDO of the first device to the DIN input of the next device in
the chain, a multidevice interface is constructed. Each device in
the system requires 24 clock pulses. Therefore, the total number
of clock cycles must equal 24N, where N is the total number of
AD5744/64s in the chain. When the serial transfer to all devices
is complete, SYNC is taken high. This latches the input data in
each device in the daisy chain and prevents any further data
from being clocked into the input shift register. The serial clock
may be a continuous or a gated clock. A continuous SCLK
source can only be used if SYNC is held low for the correct
number of clock cycles. In gated clock mode, a burst clock
containing the exact number of clock cycles must be used and
SYNC must be taken high after the final clock to latch the data.
Readback Operation
Readback mode is invoked by setting the R/W bit = 1 in the
serial input register write. With R/W = 1, Bits A2–A0, in
association with Bits REG2 , REG1, and REG0, select the
register to be read. The remaining data bits in the write
sequence are don’t cares. During the next SPI write, the data
appearing on the SDO output will contain the data from the
previously addressed register. For a read of a single register, the
NOP command can be used in clocking out the data from the
selected register on SDO. The readback diagram in Figure 4
shows the readback sequence. For example, to read back the
fine gain register of Channel A on the AD5744/64, the following
sequence should be implemented. First, write 0xA0XXXX to
the AD5744/64 input register. This configures the AD5744/64
for read mode with the fine gain register of Channel A selected.
Note that all the data bits, DB15 to DB0, are don’t cares. Follow
this with a second write, a NOP condition, 0x00XXXX. During
this write, the data from the fine gain register is clocked out on
the SDO line, i.e., data clocked out will contain the data from
the fine gain register in Bits DB5 to DB0.
SIMULTANEOUS UPDATING VIA LDAC
After data has been transferred into the input register of the
DACs, there are two ways in which the DAC registers and DAC
outputs can be updated. Depending on the status of both SYNC
and LDAC.
Individual DAC Updating
In this mode, LDAC is held low while data is being clocked into
the input shift register. The addressed DAC output is updated
on the rising edge of SYNC.
Simultaneous Updating of All DACs
In this mode, LDAC is held high while data is being clocked
into the input shift register. All DAC outputs are updated by
taking LDAC low any time after SYNC has been taken high.
The update now occurs on the falling edge of LDAC.
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AD5744ASU 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:Complete, Quad, 14/16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC
AD5744BSU 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:Complete, Quad, 14/16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC
AD5744CSU 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:Complete, Quad, 14/16-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC
AD5744R 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:Complete Quad, 14-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC
AD5744R_08 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:Complete Quad, 14-Bit, High Accuracy, Serial Input, Bipolar Voltage Output DAC