AD5382
AD5382 INTERFACES
The AD5382 contains both parallel and serial interfaces.
Furthermore, the serial interface can be programmed to be
either SPI, DSP, MICROWIRE, or I2C compatible. The SER/
Figure 3 and Figure 5 show timing diagrams for a serial write to
the AD5382 in standalone and daisy-chain modes. The 24-bit
data-word format for the serial interface is shown in Table 19
PAR
pin selects parallel and serial interface modes. In serial mode,
/B. When toggle mode is enabled, this pin selects whether the
data write is to the A or B register. With toggle disabled, this bit
should be set to zero to select the A data register.
A
the
/I2C pin is used to select DSP, SPI, MICROWIRE, or I2C
SPI
interface mode.
The devices use an internal FIFO memory to allow high speed
successive writes in parallel interface mode. The user can con-
tinue writing new data to the device while write instructions are
R/ is the read or write control bit.
W
A4–A0 are used to address the input channels.
being executed. The
signal indicates the current status of
BUSY
REG1 and REG0 select the register to which data is written, as
shown in Table 11.
the device, going low while instructions in the FIFO are being
executed. In parallel mode, up to 128 successive instructions can
be written to the FIFO at maximum speed. When the FIFO is
full, any further writes to the device are ignored.
DB13–DB0 contain the input data-word.
X is a don’t care condition.
To minimize both the power consumption of the device and the
on-chip digital noise, the active interface only powers up fully
when the device is being written to, i.e., on the falling edge of
Standalone Mode
By connecting the DCEN (Daisy-Chain Enable) pin low, stand-
alone mode is enabled. The serial interface works with both a
continuous and a noncontinuous serial clock. The first falling
or the falling edge of
.
WR
SYNC
DSP, SPI, MICROWIRE COMPATIBLE SERIAL
INTERFACES
edge of
starts the write cycle and resets a counter that
SYNC
counts the number of serial clocks to ensure that the correct
number of bits are shifted into the serial shift register. Any
The serial interface can be operated with a minimum of three
wires in standalone mode or four wires in daisy-chain mode.
Daisy chaining allows many devices to be cascaded together to
further edges on
except for a falling edge are ignored
SYNC
until 24 bits are clocked in. Once 24 bits have been shifted in,
the SCLK is ignored. In order for another serial transfer to take
place, the counter must be reset by the falling edge of
increase system channel count. The SER/
pin must be tied
PAR
high and the
/I2C pin (Pin 97) should be tied low to enable
SPI
.
SYNC
the DSP/SPI/MICROWIRE compatible serial interface. In serial
interface mode, the user does not need to drive the parallel
input data pins. The serial interface’s control pins are
, DIN, SCLK—Standard 3-Wire Interface Pins.
SYNC
DCEN—Selects Standalone Mode or Daisy-Chain Mode.
SDO—Data Out Pin for Daisy-Chain Mode.
Table 19. 32-Channel, 14-Bit DAC Serial Input Register Configuration
MSB
LSB
A
/B
W
R/
0
A4
A3
A2
A1
A0
REG1
REG0
DB13
DB12
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
Rev. 0 | Page 26 of 40
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