2. Unlock Detection Software

Figure 3

3. When Outputting Unlock Data Using Serial Data Output:

Once the LC72136 detects an unlocked state, it does not reset the unlock data (UL) until the next data output (or data

input) operation is performed. At the data output Πpoint in Figure 3, although the VCO frequency is stable (locked),

the unlock data remains set to the unlocked state since no data output has been performed since the value of N was

changed. Thus, even though the frequency became stable (locked), from the point of view of the data, the circuit is in

the unlocked state. Therefore, the data output Πimmediately following a change to the value of N should be seen as

a dummy data, and the data from the second data output (data output ) and later outputs should be seen as valid

data.

Lock Determination Flowchart

No. 5038-19/23

LC72136, 72136M