tea5761uk NXP Semiconductors, tea5761uk Datasheet - Page 7

• Manufacturer Part Number: tea5761uk
• Description: Tea5761uk Low-voltage Single Chip Fm-stereo Radio
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13451
Product data sheet
8.5 PLL tuning system
8.6 Band limits
The PLL synthesizer tuning system is suitable to operate with a 32.768 kHz reference
frequency generated by the crystal oscillator or a reference clock of 32.768 kHz fed into
the TEA5761UK. To tune the radio to the required frequency requires the PLL word to be
calculated and then programmed to the register. The PLL word is 14 bits long; see
Table 12
Formula for high-side injection:
Formula for low-side injection:
where:
Example for receiving a channel at 100.1 MHz:
The result found using
integer value. If rounded down to the lowest integer value of N
becomes 2FD6h.
This value can be written to register FRQSET via the I
then start an autonomous search at this frequency or go to a preset channel at this
frequency. When the application is built according to the application diagram (see
Figure
within 40 ms.
The PLL is triggered by writing to any one of the bytes FRQSETMSB, FRQSETLSB,
TNCTRL1, TNCTRL2, TESTBITS, TESTMODE.
Accurate validation of the PLL locking on the new frequency can take 40 ms. When a lock
is detected bit LD is set.
The TEA5761UK can be switched to the Japanese FM band or to the US and Europe FM
band. Setting bit BLIM to logic 0 the band range is 87.5 MHz to 108 MHz; setting bit
BLIM to logic 1 selects the Japanese band range of 76 MHz to 90 MHz.
N
N
N
DEC
DEC
N
f
f
f
DEC
RF
IF
ref
DEC
= intermediate frequency of 225 kHz
= reference frequency of 32.768 kHz
= wanted tuning frequency (Hz)
=
=
=
13) and with the preferred components, the PLL will settle to the new frequency
= decimal value of PLL word
and
4
------------------------------------- -
4
------------------------------------- -
4
----------------------------------------------------------------------- -
Table
100.1 10
f
f
f
f
RF
RF
ref
ref
+
–
13. Calculation of this 14-bit word can be done as follows.
f
f
32768
IF
IF
Rev. 01 — 2 August 2006
Equation 1
6
+
225 10
or
3
Equation 2
=
12246.704
Low voltage single-chip FM stereo radio
must always be rounded to the lowest
2
C-bus and the TEA5761UK will
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
DEC
TEA5761UK
= 12246, the PLL word
7 of 44
(1)
(2)
(3)