DAC39RF10 datasheet(110/232 Pages) TI2

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NCO Output

Frequency changed to

frequency 2

Frequency changed to

frequency 1

Figure 7-44. Example Phase Continuous NCO Mode Operation

7.3.6.1.2.2 Phase-coherent NCO Update Mode

The phase-coherent NCO update mode, the frequency word is updated and is multiplied by a counter to

update the accumulator. This allows the phase for a particular frequency to be "coherent" with the previous

usage of the frequency as if the NCO had never been tuned away from that frequency. Since the phase

information is maintained by the counter, any frequency can be phase coherent. Phase Coherent NCO Mode

operation is demonstrated in Figure 7-45 and selected by programming NCO_CONT = 0 and NCO_AR = 0. If

alignment between multiple devices is required, then NCO_AR must be programmed to 1 during the initial NCO

synchronization to align the master accumulator for all devices.

Frequency 1

Frequency 2

NCO Output

Frequency changed to

frequency 2

Frequency changed to

frequency 1

Figure 7-45. Example Phase Coherent NCO Mode Operation

7.3.6.1.2.3 Phase-sync NCO Update Mode

In Phase-sync NCO update mode, the frequency word is updated (if it changed) and the accumulator is reset.

This mode can be used to align the NCOs across multiple devices by providing a synchronization signal

simultaneously across all devices. This mode is selected by programming NCO_AR = 1.

7.3.6.1.2.4 NCO Synchronization

Many systems required synchronization between DAC channels including the phase of the internal NCOs when

using digital up-conversion features. Further, frequency hopping systems may have additional requirements

for synchronized frequency hopping to maintain NCO synchronization during changes in NCO frequency. The

device has a number of ways to update NCO changes. These include:

• Synchronization through the LSB of the "I" input of DUC0 in the JESD204C input data stream

• Synchronization through SYSREF

• Update through SPI_SYNC register bit

• Update on the rising edge of FRCS of the FRI interface if the FRS bit is set.

DAC39RF10-SP, DAC39RF10-SEP

DAC39RFS10-SP, DAC39RFS10-SEP

SBAS932A – MARCH 2024 – REVISED FEBRUARY 2026

www.ti.com

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