lc72130m Sanyo Semiconductor Corporation, lc72130m Datasheet - Page 19

• Manufacturer Part Number: lc72130m
• Description: Am/fm Pll Frequency Synthesizer
• Manufacturer: Sanyo Semiconductor Corporation

2. Unlock Determination Software Integration Method
3. Unlocked State Data Output Using Serial Data Output
4. Directly Outputting Unlocked State Data from the DO Pin (Set by the DO pin control data)
In the LC72130, once an unlocked state occurs, the unlocked state serial data (UL) will not be reset until a data input
(or output) operation is performed. At the data output 1 point in Figure 3, although the VCO frequency has stabilized
(locked), since no data output has been performed since the divisor N was changed the unlocked state data remains in
the unlocked state. As a result, even though the frequency has stabilized (locked), the system remains (from the
standpoint of the data) in the unlocked state.
Therefore, the unlocked state data acquired at data output 1, which occurs immediately after the divisor N was
changed, should be treated as a dummy data output and ignored. The second data output (data output 2) and
following outputs are valid data.
Since the locking state (high = locked, low = unlocked) is output directly from the DO pin, the dummy data
processing described in section 3 above is not required. After changing the divisor N, the locking state can be
checked after waiting at least two reference frequency periods.
Locked State Determination Flowchart
LC72130, 72130M
Figure 3
No. 4973-19/22