54
8Bit Single Chip Microcontroller
DMC73C168
- UNLOCK F/F DETECTION TIME SELECTOR BIT
This bit must be set to satisfy your applied UNLOCK F/F detection time specification.
UNLOCK F/F detects the PLL Locking status affer detection time duration.
Fref
Programmable
Counter Output
Error Out
UNLOCK F/F
Detection Time
T1
T2
T1
T2
Figure 5-7-2. UNLOCK F/F DETECTION TIME
For example, if you select detection time - T1, UL F/F output is UNLOCK STATES, but you select
Detection time - T2, UL F/F output is Lock status under the same Error output conditions. This is very
useful to compensate for mechanical oscillation of VCO. Figure 5-7-2 shows two kinds of detection time
(T1 and T2) as for example.
- REFERENCE FREQUENCY SELECTOR BIT
These bits select reference frequency specification which is inputs to phase detector to compare the
phase difference with the VCO output divided by the programmable divider.
PLLCTL0
(P16,5,4,3)
1KHz
5KHz
6.25KHz
SEL
9KHz
TO PHASE
DETECTOR
12.5KHz
25KHz
50KHz
OSCIN
REF. FREQ. DIVIDER
450K 100K 6.25K 5K
OSCOUT
SYSTEM CLOCK
1K
For beep clock
Figure 5-7-3. REFERENCE FREQUENCY SELECTOR BIT
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