Datasheet

AD9959

Rev. B | Page 40 of 44

Bit Mnemonic Description

5 SYNC_CLK disable 0 = the SYNC_CLK pin is active (default).

1 = the SYNC_CLK pin assumes a static Logic 0 state (disabled). In this state, the pin drive logic is

shut down. However, the synchronization circuitry remains active internally to maintain normal

device operation.

4 DAC reference power-down 0 = DAC reference is enabled (default).

1 = DAC reference is powered down.

3:2 Open See the Synchronizing Multiple AD9959 Devices section for details.

1 Manual hardware sync 0 = the manual hardware synchronization feature of multiple devices is inactive (default).

1 = the manual hardware synchronization feature of multiple devices is active.

0 Manual software sync 0 = the manual software synchronization feature of multiple devices is inactive (default).

1 = the manual software synchronization feature of multiple devices is active. See the

Synchronizing Multiple AD9959 Devices section for details.

Function Register 2 (FR2)—Address 0x02

Two bytes are assigned to this register. The FR2 is used to control the various functions, features, and modes of the AD9959.

Table 33. Bit Descriptions for FR2

Bit Mnemonic Description

All channels autoclear sweep

accumulator

0 = a new delta word is applied to the input, as in normal operation, but not loaded into the

accumulator (default).

1 = this bit automatically and synchronously clears (loads 0s into) the sweep accumulator for one

cycle upon reception of the I/O_UPDATE sequence indicator on all four channels.

14 All channels clear 0 = the sweep accumulator functions as normal (default).

sweep accumulator 1 = the sweep accumulator memory elements for all four channels are asynchronously cleared.

All channels autoclear phase

accumulator

0 = a new frequency tuning word is applied to the inputs of the phase accumulator, but not

loaded into the accumulator (default).

1 = this bit automatically and synchronously clears (loads 0s into) the phase accumulator for one

cycle upon receipt of the I/O update sequence indicator on all four channels.

12 All channels clear phase 0 = the phase accumulator functions as normal (default).

accumulator 1 = the phase accumulator memory elements for all four channels are asynchronously cleared.

11:8 Open

7 Auto sync enable See the Synchronizing Multiple AD9959 Devices section for more details.

6 Multidevice sync master enable See the Synchronizing Multiple AD9959 Devices section for more details.

5 Multidevice sync status See the Synchronizing Multiple AD9959 Devices section for more details.

4 Multidevice sync mask See the Synchronizing Multiple AD9959 Devices section for more details.

3: 2 Open

1:0 System clock offset See the Synchronizing Multiple AD9959 Devices section for more details.