UPD17073 NEC, UPD17073 Datasheet - Page 136

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

15.4.2 Functions of phase comparator
against reference frequency “f
136
As shown in Figure 15-8, the phase comparator compares the output frequency of the programmable divider “f
That is, if f
Figure 15-9 shows the relations among f
In the PLL disable status, neither UP nor DOWN request signal is output.
The UP and DOWN request signals are input to the charge pump and unlock FF.
(a) If f
(b) If f
(c) If f
(d) If f
UP
DW
UP
DW
UP
DW
f
f
f
f
f
f
f
UP
DW
f
r
N
r
N
r
N
r
N
N
N
N
N
lags behind f
and f
advances f
is lower than f
N
is lower than f
r
are in phase
r
r
r
r
, it outputs the UP request signal; if f
r
”, and outputs UP or DOWN request signal.
Figure 15-9. Relations among f
r
, f
N
, and UP and DOWN request signals.
N
is higher than f
r
, f
N
, UP, and DW
r
, the DOWN request signal is output.
PD17072,17073
N
”