DAC39RF10 datasheet(198/232 Pages) TI2

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1. 1. Fast approach using ESVO_S:

a. Repeat the procedure above for each valid value of ESPO. For each value of ESPO, run an inner-eye

analysis of zeros and ones. This locates the maximum zero (ESVOmax0 ) and minimum one (ESVOmin1)

for each value of ESPO.

b. All the cells of the eye between ESVOmax0 and ESVOmin1 (inclusive) can be colored black, and all other

cells colored white.

c. Additional detail can be added to the eye-diagram by including outer and/or average analysis (see ES).

For example, the ESVO_S values produced from average analysis can be colored red, while all other

values between and including the inner and outer values colored white.

2. Detailed approach using ECOUNT:

a. select an eye-scan mode that counts mismatches. Repeat the procedure outlined above for each valid

value of ESVO and ESPO.

b. After each run, record the value of ECOUNT (resetting ECOUNT before each run).

c. Each eye-scan run corresponds to one cell of the eye-diagram. ESPO is the x-coordinate of the cell.

ESVO is the y-coordinate of the cell. The intensity of the cell is proportional to ECOUNT/Nsamples,

where Nsamples is the number of analyzed samples per run (determined by ESLEN).

d. This approach takes much more time to run, but can provide a more granular eye-diagram.

9.1.5 Pre/Post Cursor Analysis Procedure

Pre/Post Cursor Analysis can be used to determine an optimum setting for pre-emphasis in the transmitter.

1. Program JESD_EN = 0 if necessary. Program EQMODE = 1. Program JESD_EN = 1 and allow sufficient

time for the equalizer to adapt and settle. You can read EQLEVEL_S multiple times to verify the value is

stable or toggling between adjacent values.

2. Set EQHOLD = 1 to lock the equalizer (disable adaptation). This also causes EQOVER and EQUNDER

fields to become low.

3. Wait at least 48UI, and proportionally longer if the CDR activity is less than 100% so the 1 on EQHOLD is

sampled and acted upon. The SPI is slow enough that no explicit delay is be necessary.

4. Set EQMODE to 2 or 3 to select pre or post cursor analysis respectively. With a separate SPI transaction,

set EQHOLD = 0. The equalization characteristics of the received signal are analyzed (the equalizer

response continues to be locked).

5. Wait at least 150,000UI to allow time for the analysis to occur, proportionately longer if the CDR activity is

less than 100%

6. Examine EQOVER and EQUNDER for results of analysis:

a. EQOVER high indicates the signal is over equalized;

b. EQUNDER high indicates the signal is under equalized;

7. Set EQHOLD = 1

8. Adjust the transmitter pre-emphasis and repeat steps 3 thru 7 if required.

9. Set EQMODE = 1, and with a separate SPI transaction, set EQHOLD = 0 to exit analysis mode and return to

normal adaptive equalization.

9.1.6 Sleep and Disable Modes

There are several methods to power down or temporarily disable the DAC outputs. To prevent asymmetric aging

of the device circuits, in some options a low level output from the DACs is maintained. Table 9-1 lists the options

for sleep or disabling the DAC outputs.

The most power is saved in full power down, which is enable by setting the MODE register to 0x3. In this mode

a low level output signal is maintained to prevent asymmetric aging. Returning to full operation from full power

down takes 100's of microseconds.

One or both DAC outputs can be disabled by setting the corresponding MXMODE register to 0x6. This saves

some power and the DAC outputs a low level signal to prevent asymmetric aging. If only one channel is

DAC39RF10-SP, DAC39RF10-SEP

DAC39RFS10-SP, DAC39RFS10-SEP

SBAS932A – MARCH 2024 – REVISED FEBRUARY 2026

www.ti.com

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