lc72133m Sanyo Semiconductor Corporation, lc72133m Datasheet - Page 18

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

Unlock Detection Timing
1. Unlock Detection Determination Timing
Unlocked state detection is performed in the reference frequency (fref) period (interval). Therefore, in principle,
unlock determination requires a time longer than the period of the reference frequency. However, immediately after
changing the divisor N (frequency) unlock detection must be performed after waiting at least two periods of the
reference frequency.
For example, if fref is 1 kHz, i.e., the period is 1 ms, after changing the divisor N, the system must wait at least 2 ms
before checking for the unlocked state.
øERROR
(unlock)
VCO
CE
DATA
LATCH
VCO/N
N-
counter
fref
Old data
DATA LATCH
Figure 1 Unlocked State Detection Timing
R
N
Old divisor N
Note: After changing the divisor, øERROR
The divisor N is not updated
in the first period.
New data
Figure 2 Circuit Structure
is output after two fref periods.
Preset
LC72133M, 72133V
VCO/N
fref
New divisor N'
Phase comparator
detection circuit
Unlock
UNLOCK
øERROR
L. P. F
A11937
No. 5427-18/23
A11936