TDA7333 Datasheet, PDF (5/21 Pages) STMicroelectronics – RDS/RBDS PROCESSOR

TDA7333
Table 6. Electrical Characteristics (continued)
Symbol
Parameter
R_p
f_stop
R_s
M_i
I²C
f_I2C
SPI
f_SPI
t_ch
t_cl
t_csu
t_csh
t_odv
t_oh
t_d
t_su
t_h
Passband Ripple
Stopband Corner Frequencies
Stopband Attenuation
Interpolation Factor
clock frequency in I²C mode
clock frequency in SPI mode
clock high time
clock low time
chip select setup time
chip select hold
output data valid
output hold
deselect time
data setup time
data hold time
Test Conditions
Values
Unit
Min. Typ. Max.
-0.5
+0.5 dB
53.0
61 kHz
-43
dB
32
400 kHz
450
450
500
500
0
1000
200
200
1 MHz
ns
ns
ns
ns
250 ns
ns
ns
ns
ns
7 Functional Description
7.1 Overview
The new RDS/RBDS processor contains all RDS/RBDS relevant functions on a single chip. It recovers the
inaudible RDS/RBDS information which are transmitted on most FM radio broadcasting stations.
Due to an integrated 3rd order sigma delta converter, which samples the MPX signal, all further processing
is done in the digital domain and therefore very economical. After filtering the highly oversampled output
of the A/D converter, the RDS/RBDS demodulator extracts the RDS DataClock , RDS Data Signal and
the Quality information. A next RDS/RBDS decoder will synchronize the bitwise RDS stream to a group
and block wise information. This processing includes an error detection and error correction algorithm. In
addition, an automatic flywheel control avoids exhaustive data exchange between the RDS/RBDS proces-
sor and the host.
The device operates in accordance with the EBU (European Broadcasting Union) specifications.
7.2 Sigma Delta Converter
The Sigma Delta Modulator is a 3rd order (second order-first order cascade) structure. Therefore a multibit out-
put (2 bit streams) represents the analog input signal. A next digital noise canceller will take the 2 bit streams
and calculates a combined stream which is then fed to the decimation filter. The modulator works at a sampling
frequency of XTI/2. The oversampling factor in relation to the band of interest (57 kHz +- 2.4 kHz) is 38.
7.3 Sinc4/16 Decimation Filter
The oversampled data delivered from the modulator are decimated by a value of 16 with a 4th order Sinc Filter.
This is considered to be the optimum solution for high decimation factors and for a 3rd order sigma delta mod-
ulator.
5/21