AD5758 datasheet(52/72 Pages) AD

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AD5758

Data Sheet

Rev. 0 | Page 52 of 72

PROGRAMMING SEQUENCE TO ENABLE THE

OUTPUT

To write to and set up the device from a power-on or reset

condition, use the following procedure:

Perform a hardware or software reset and wait 100 μs.

Perform a calibration memory refresh by writing 0xFCBA to

the key register. Wait a minimum of 500 μs before proceeding

to Step 3 to allow time for the internal calibrations to

complete. As an alternative to waiting 500 μs for the refresh

cycle to complete, poll the CAL_MEM_UNREFRESHED bit

in the DIGITAL_DIAG_RESULTS register until it is 0.

Write 1 to Bit D13 in the DIGITAL_DIAG_RESULTS register

to clear the RESET_OCCURRED flag.

If CLKOUT is required, configure and enable this feature

via the GP_CONFIG1 register. It is important to configure

this feature before enabling the dc-to-dc converter.

Write to the DCDC_CONFIG2 register to set the dc-to-dc

current limit. Wait 300 μs to allow the 3-wire interface

communication to complete. As an alternative to waiting

300 μs for the 3-wire interface communication to complete,

poll the BUSY_3WI bit in the DCDC_CONFIG2 register

until it is 0.

Write to the DCDC_CONFIG1 register to set up the dc-to-

dc converter mode (thereby enabling the dc-to-dc converter)

and to close the fault protection switch (FPS). Wait 300 μs

to allow the 3-wire interface communication to complete.

As an alternative to waiting 300 μs to the 3-wire interface

communication to complete, poll the BUSY_3WI bit in the

DCDC_CONFIG2 register until it is 0.

Write to the DAC_CONFIG register to set the INT_EN bit

(powers up the DAC and internal amplifiers without enabling

the output) and configure the output range, internal/external

RSET, and slew rate. Keep the OUT_EN bit disabled at this

point. Wait 500 μs minimum before proceeding to Step 8 to

allow time for the internal calibrations to complete. As an

alternative to waiting 500 μs for the refresh cycle to

complete, poll the CAL_MEM_ UNREFRESHED bit in the

DIGITAL_DIAG_RESULTS register until it is 0.

Write zero-scale DAC code to the DAC_INPUT register.

(If a bipolar range was selected in Step 7, then a DAC code

that rep

resents a 0 mA/0 V output must be written to the

DAC_INPUT register). It is important that this step be

completed even if the contents of the DAC_INPUT register

are not changing.

If LDAC functionality is being used, perform either a

software or hardware LDAC command.

10. Rewrite the same word to the DAC_CONFIG register as in

Step 7 except, this time, with the OUT_EN bit enabled.

Allow 1.25 ms minimum between Step 6 and Step 9; this is

the time from when the dc-to-dc is enabled to when the

VIOUT output is enabled.

11. Write the required DAC code to the DAC_INPUT register.

An example configuration is shown in Figure 92.

Changing and Reprogramming the Range

After the output is enabled, use the following recommended

steps when changing the output range:

Write to the DAC_INPUT register. Set the output to 0 mA

or 0 V.

Write to the DAC_CONFIG register. Disable the output

(OUT_EN = 0), and set the new output range. Keep the

INT_EN bit set. Wait 500 μs minimum before proceeding

to Step 3 to allow time for internal calibrations to complete.

Write Code 0x0000 (in the case of bipolar ranges, write

Code 0x8000) to the DAC_INPUT register. It is important

that this step be completed even if the contents of the

DAC_INPUT register are not changing.

Reload the DAC_CONFIG register word from Step 2 except,

this time, set the OUT_EN bit to 1 to enable the output.

Write the required DAC code to the DAC_INPUT register.

AD5758 Datasheet(PDF) 52 Page - Analog Devices

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