Data Sheet

ADRF5720

Rev. 0 | Page 15 of 19

PARALLEL MODE INTERFACE

The ADRF5720 has six digital control inputs, D0 (LSB) to D5

(MSB), to select the desired attenuation state in parallel mode, as

shown in Table 7. The parallel control interface is activated when

PS is set to low.

There are two modes of parallel operation: direct parallel and

latched parallel.

Direct Parallel Mode

To enable direct parallel mode, the LE pin must be kept high.

The attenuation state is changed by the control voltage inputs

(D0 to D5) directly. This mode is ideal for manual control of the

attenuator.

Latched Parallel Mode

To enable latched parallel mode, the LE pin must be kept low

when changing the control voltage inputs (D0 to D5) to set the

attenuation state. When the desired state is set, LE must be

toggled high to transfer the 6-bit data to the bypass switches of

the attenuator array, and then toggled low to latch the change

into the device until the next desired attenuation change (see

Figure 36 in conjunction with Table 2).

Figure 36. Latched Parallel Mode Timing Diagram

D5 TO D0

PS

LE

X

X

X