TDA5150 Datasheet, PDF (29/106 Pages) Infineon Technologies AG – On-chip, high resolution fractional-N synthesizer and Sigma-Delta modulator with ASK, FSK, GFSK options

TDA 5150
TDA 5150 Functional Description
The Data Encoder option is enabled by bit C of Transmit Command (Data Encoder
enabled if bit C=1). See also Chapter 2.4.3.4 Transmit Command for command
structure. If the Data Encoder is enabled, bit A must to be set for Synchronous
Transmission Mode as well (Bit A=1 and Bit C=1, this last to enable encoding).
The selection of encoding mode is done via bits ENCODE (0x05.2:0) of SFR TXCFG1.
(0x05). At the same time bit INVERT (0x05.3) of the same SFR enables the inversion of
an already encoded bit stream.
The encoding activation entry point can be configured in SFR ENCCNT (0x27).
By initializing the SFR ENCCNT (0x27) with 0x00, already the first bit is encoded. If for
example ENCCNT = 0x10, the first 16 bits should remain unencoded. This method
allows to keep the first N bits unencoded within a datagram (in fact plain NRZ), followed
by encoded bits (of the same datagram).The encoding scheme is selected by bit-field
ENCMODE (0x05.2:0) of SFR TXCFG1.
2.4.4.1 PRBS9 Generator, Data Scrambler
TDA 5150 contains a PRBS9 generator, suitable for generation of pseudo-random NRZ
data patterns.The PRBS9 datastream satisfies (in general lines) the requirements for
random distribution (even if longer PRBS polynomials come closer to “true” random
distribution) and therefore it can be useful for Transmitter RF tests, for instance by
measurement of the “Occupied RF Bandwidth”.
In addition the generated PRBS9 pattern can be XOR’ed with a real data pattern sent by
the microcontroller and this way “scramble” this data pattern.
Attention: The data scrambling functionality is intended to enhance the clock
recovery performance of the Receiver Station. It is not suitable, as
stand-alone encryption method for security applications!
PRBS9 is a well known standard in the class of pseudo-random patterns, and is
implemented within the TDA 5150 by a subpart with following block diagram:
BDR CLK
76543210
D
D
D
D
D
D
D
D
PRBS Start value
loaded @ start of TX
to
modulator
SDIO
Figure 11
D
PRBS9 Generator and Data Scrambler
Data Sheet
29
V 1.0, July 2009