UPD17073 NEC, UPD17073 Datasheet - Page 142

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

15.6.3 Pulse swallow mode (VHF)
142
(1) Selecting division mode
(2) Pin to be used
(3) Setting of reference frequency f
(4) Calculating division value N
(5) Example of PLL data setting
Note
Then set the PLL data register, PLL mode select register, and PLL reference frequency select register as follows:
Select the pulse swallow mode by the PLL mode select register.
The VCOH pin is enabled when the pulse swallow mode is selected.
Set the reference frequency by using the PLL reference frequency select register.
Calculate as follows:
where,
Suppose that broadcasting in the following FM band is to be received:
The division ratio N is:
The signal input from VCOH pin is divided by two immediately before input to the programmable divider.
N =
Receive frequency
Reference frequency
Intermediate frequency
N =
0
f
0
VCOH
f
f
f
VCOH
r
VCOH
f
r
f
0
r
0
: input frequency of VCOH pin
: reference frequency
0
1
2
0
Note
1
2
Note
1
=
100.0 + 10.7
0
PLL data register
8
0.025
0
:
:
:
100.0 MHz (FM band)
+10.7 MHz
0
r
1
25 kHz
0
A
1
1
2
Note
0
= 2214 (decimal)
= 08A6 (hexadecimal)
0
1
6
1
0
0
PLL mode
select
register
VHF
0
1
0
PLL reference
frequency
select register
0
25 kHz
1
0
PD17072,17073
1