AD5390BST-5 Analog Devices Inc, AD5390BST-5 Datasheet - Page 25

• Manufacturer Part Number: AD5390BST-5
• Description: IC DAC 14BIT I2C 16CH 52-LQFP
• Manufacturer: Analog Devices Inc

Specifications of AD5390BST-5

• Rohs Status: RoHS non-compliant
• Design Resources: 8 to 16 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using AD5390/1/2 (CN0029) AD5390/91/92 Channel Monitor Function (CN0030)
• Settling Time: 8µs
• Number Of Bits: 14
• Data Interface: I²C, Serial
• Number Of Converters: 16
• Voltage Supply Source: Single Supply
• Power Dissipation (max): 35mW
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 52-LQFP
• For Use With: EVAL-AD5390EBZ - BOARD EVALUATION FOR AD5390

Standalone Mode
By connecting the daisy-chain enable (DCEN) pin low, stand-
alone mode is enabled. The serial interface works with both a
continuous and a noncontinuous serial clock. The first falling
edge of SYNC starts the write cycle and resets a counter that
counts the number of serial clocks to ensure that the correct
number of bits is shifted into the serial shift register. Any
further edges on SYNC (except for a falling edge) are ignored
until 24 bits are clocked in. Once 24 bits have been shifted in,
the SCLK is ignored. For another serial transfer to take place,
the counter must be reset by the falling edge of SYNC .
Daisy-Chain Mode
For systems that contain several devices, the SDO pin can be
used to daisy-chain the devices together. This daisy-chain mode
can be useful in system diagnostics and for reducing the number
of serial interface lines.
By connecting the DCEN pin high, daisy-chain mode is
enabled. 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 on the next device in the chain,
a multidevice interface is constructed. For each device in the
system, 24 clock pulses are required. Therefore, the total
number of clock cycles must equal 24N where N is the total
number of AD539x devices 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.
If SYNC is taken high before 24 clocks are clocked into the part,
it is considered a bad frame and the data is discarded.
SYNC
SCLK
SDO
DIN
INPUT WORD SPECIFIES REGISTER TO BE READ
DB23
DB23
UNDEFINED
24
Figure 32. Readback Operation
DB0
DB0
Rev. C | Page 25 of 40
DB23
DB23
SELECTED REGISTER DATA CLOCKED OUT
The serial clock can be either a continuous or a gated clock. A
continuous SCLK source can be used only if the SYNC can be
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 taken high after the final clock to latch
the data.
Readback Mode
Readback mode is invoked by setting the R/ W bit = 1 in the serial
input register write sequence. With R/ W = 1, Bit A3 to Bit A0
in association with Bits REG1 and REG0 select the register to
be read. The remaining data bits in the write sequence are don’t
care bits. During the next SPI write, the data appearing on the
SDO output contains 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 32 shows the readback sequence.
For example, to read back the m register of Channel 0 on the
AD539x, the following sequence should be implemented:
First, write 0x404XXX to the AD539x input register. This
configures the AD539x for read mode with the m register of
Channel 0 selected. Note that all data bits, DB13 to DB0, are
don’t care bits.
Follow this with a second write, a NOP condition, and 0x000000.
During this write, the data from the m register is clocked out on
the DOUT line, that is, data clocked out contains the data from
the m register in Bit DB13 to Bit DB0, and the top 10 bits con-
tain the address information as previously written. In readback
mode, the SYNC signal must frame the data. Data is clocked out
on the rising edge of SCLK and is valid on the falling edge of
the SCLK signal. If the SCLK idles high between the write and
read operations of a readback, the first bit of data is clocked out
on the falling edge of SYNC .
NOP CONDITION
AD5390/AD5391/AD5392
48
DB0
DB0