tea5766uk NXP Semiconductors, tea5766uk Datasheet - Page 6

• Manufacturer Part Number: tea5766uk
• Description: Tea5766uk Stereo Fm Radio + Rds
• Manufacturer: NXP Semiconductors

NXP Semiconductors
7. Functional description
TEA5766UK_1
Product data sheet
7.1 Low noise RF amplifier
7.2 FM mixer
7.3 VCO
7.4 Reference frequency
7.5 Tuning system
Table 3.
[1]
The Low Noise Amplifier (LNA) input impedance together with the LC RF input circuit
defines an FM band filter. The gain of the LNA is controlled by the RF Automatic Gain
Control (AGC) circuit to prevent overdrive of the subsequent circuits.
The FM quadrature mixer converts the received RF (76 MHz to 108 MHz) to the IF of
225 kHz. Downconversion is achieved by multiplication of the RF with the Local Oscillator
(LO) frequency. Image frequency suppression is achieved by using quadrature signal
processing.
The LC tuned VCO provides the local oscillator signal for the downconversion of the RF
signal to IF. The VCO is tuned to the double frequency required for the downconversion.
The LO is divided by two to provide the quadrature oscillator signals for the
downconversion process. The VCO frequency range is from 150 MHz to 217 MHz.
Integrated varactors are used for the VCO tuning. The only external component used for
the VCO is a coil.
An external 32.768 kHz reference frequency is used as system clock. The reference clock
specifications are given in
The reference frequency is used for:
The PLL synthesizer tuning system is suitable to operate with a 32.768 kHz reference
frequency. A 14-bit word is used to tune the radio, see
word shall be done as follows:
Symbol
MPXOUT
VAFL
VAFR
•
•
•
•
•
The ISS pin the bus type can be selected, see
Synthesizer PLL reference frequency
Timing for the IF counter
Adjustment of the 38 kHz VCO for the stereo decoder
Auto alignment of the selectivity as well as the demodulator filters
Auto alignment of the 57 kHz RDS filter
Pin description
Pin
E4
E5
E6
Rev. 01 — 22 March 2007
…continued
Section
Description
multiplex signal (MPX) output
left audio output
right audio output
13.2.
Section
10.1.
Table
15. Calculation of this 14-bit
TEA5766UK
Stereo FM radio + RDS
© NXP B.V. 2007. All rights reserved.
5 of 59