AD5755-1x AD [Analog Devices], AD5755-1x Datasheet - Page 19

• Manufacturer Part Number: AD5755-1x
• Description: Quad Channel, 16-Bit, Serial Input, 4-20mA & Voltage Output DAC, Dynamic Power Control, HART Connectivity
• Manufacturer: AD [Analog Devices]

Preliminary Technical Data
PROGRAMMING SEQUENCE TO WRITE/ENABLE
THE OUTPUT CORRECTLY
To correctly write to and set up the part from a power on
condition the sequence below should be followed. It is
recommended to perform a hardware or software reset after
initial power on.
Firstly, the DC-DC supply block needs to be configured. The
user should set the DC-DC switching frequency, max output
voltage allowed and the phase that the 4 DC-DC channels clock
at. Secondly the DAC Control Register should be configured on
a per channel basis. The output range is selected, and the DC-
DC block is enabled (DC-DC). Other control bits may be
configured at this point, however, the output enable bit
(OUTEN) and the INT_ENABLE bit should not be set. Next,
the user writes the required code to the DAC Data Register.
This will implement a full DAC calibration internally. Finally
the user writes to the DAC Control Register again to enable the
output (set the OUTEN bit). A flow chart of this sequence is
shown below.
Figure 17. Programming Sequence for Enabling the Output Correctly
Step 1: Perform a Software/Hardware Reset
Step 2: Write to DC-DC Control Register to
Step 3: Write to DAC Control Register. Select
Step 4: Write to each/all DAC Data Registers.
Step 5: Write to DAC Control Register. Reload
set DC-DC Clock Frequency, phase
and maximum voltage.
the DAC Channel and output Range.
Set the DC_DC bit and other control
bits as required. Do not select OUTEN
bit or the INT_ENABLE bit..
sequence as in Step 3 above.This time
select the OUTEN bit to enable the
output.
Power On
Rev. PrD | Page 19 of 34
CHANGING AND REPROGRAMMING THE RANGE
When changing between ranges the same sequence as above
should be used. It is recommended to set the range to its zero
point (can be mid-scale or zeroscale) prior to disabling the
output. As the DC-DC switching frequency, max voltage and
phase have already been selected, there is no need to reprogram
this. A flow chart of this sequence is shown below.
Step 1: Write to channels DAC Data Register,
Step 2: Write to DAC Control Register. Disable
Step 3: Write value to the DAC Data Register.
Step 4: Write to DAC Control Register. Reload
Figure 18. Steps for Changing the Output Range
Set the output to 0V (zero or mid-
scale).
the output (OUTEN=0), and set the
new output range. Keep the DC-DC
enabled, do not select the
INT_Enable bit.
sequence as in Step 2 above.This time
select the OUTEN bit to enable the
output.
Channels Output is enabled
AD5755-1