Data Sheet

ADRF5474

THEORY OF OPERATION

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Rev. 0 | 12 of 14

PARALLEL MODE INTERFACE

The ADRF5474 has four digital control inputs, D2 (LSB) to D5

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

shown in Table 7.

There are two modes of parallel operation: direct parallel and

latched parallel.

Direct Parallel Mode

To enable direct parallel mode, keep the LE pad high. To change

the attenuation state, use the control voltage inputs (D2 to D5)

directly. Direct parallel mode is for manual control of the attenuator.

Latched Parallel Mode

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

changing the control voltage inputs (D2 to D5) to set the attenuation

state. When the desired state is set, toggle LE high to transfer

the 4-bit data to the bypass switches of the attenuator array, and

then toggle LE low to latch the change into the device until the

next desired attenuation change (see Figure 24 and Table 2 for

additional information).

Figure 24. Latched Parallel Mode Timing Diagram