lc72133m Sanyo Semiconductor Corporation, lc72133m Datasheet - Page 19

• Manufacturer Part Number: lc72133m
• Description: Pll Frequency Synthesizer For Electronic Tuning
• Manufacturer: Sanyo Semiconductor Corporation

2. Unlock Detection Software
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 LC72133, 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
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 , 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 ) 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.
øERROR
Unlock (UL) serial
data input
Unlock detection
pin output
VCO
frequency
CE
N
Old data
Locked
Data input
Locked State Determination Flowchart
LC72133M, 72133V
New data
Divisor N modification
Dummy data output
Valid data output
Figure 3
Unlocked
(data input)
Locked?
point in Figure 3, although the VCO frequency has
*
YES
NO
...............
...............
Data output
Locked
Note: Locking state determination is more
reliable if it is based on reading valid
output data several times.
Valid data can be output at intervals
of one reference frequency period or
longer
Wait for at least two reference
frequency periods.
Data output
A11938
No. 5427-19/23