TEA5764HN View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

TEA5764HN

FM radio + RDS

Philips Electronics 

Philips Semiconductors

TEA5764HN

FM radio + RDS

8.4 Crystal oscillator

The crystal oscillator can operate with a 32.768 kHz clock crystal. The oscillator can be

overridden via the FREFIN pin. When the FREFIN pin is used the oscillator is clocked

externally by a 32.768 kHz signal. Selection between a reference clock or a reference

crystal can be done via the I2C-bus. When a crystal is connected the FREFIN pin must be

left open-circuit, and when pin FREFIN is used a crystal may not be connected. It is not

possible to connect a crystal and apply a frequency via the FREFIN pin in the same

application.

The crystal oscillator generates the reference frequency for the following:

• Reference frequency divider for synthesizer PLL

• Timing for the IF counter

• Timing for the pause detector

• Free running frequency adjustment of the stereo decoder VCO

• Centre frequency for adjustment of the IF filters

• Clock frequency of the RDS/RBDS decoder

8.5 PLL tuning system

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 TEA5764HN. 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 20 and Table 21. Calculation of this 14-bit word can be done as follows.

Formula for high-side injection:

N DEC = 4-----×-----(---f---fR---rF--e--f-+-----f---I--F----)

(1)

Formula for low-side injection:

N DEC = 4-----×-----(---f---fR--r-F-e---f-–-----f---I--F---)

(2)

where:

NDEC = decimal value of PLL word

fRF = wanted tuning frequency (Hz)

fIF = intermediate frequency of 225 kHz

fref = the reference frequency of 32.768 kHz

Example for receiving a channel at 100.1 MHz:

N DEC = -4----×-----(--1---0---0---.--1----×--3---12---07---66---8-+-----2---2---5-----×----1---0----3---) = 12246.704

(3)

TEA5764HN_2

Product data sheet

Rev. 02 — 9 August 2005

© Koninklijke Philips Electronics N.V. 2005. All rights reserved.

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