1999 May 31 5
Philips Semiconductors Product specification
Home automation modem TDA5051A
The DAC and the power stage are set in order to provide
a maximum signal level of 122 dBµV(RMS) at the output.
The output of the power stage (TXOUT) must always be
connected to a decoupling capacitor, because of a DC
level of 0.5VDD at this pin, which is present even when the
device is not transmitting. This pin must also be protected
against overvoltage and negative transient signals.
The DC level of TXOUT can be used to bias a unipolar
transient suppressor, as shown in the application diagram;
see Fig.18.
Direct connection to the mains is done through an LC
network for low-cost applications. However, a HF signal
transformer could be used when power-line insulation has
to be performed.
Reception mode
The input signal received by the modem is applied to a
wide range input amplifier with AGC (−6 to +30 dB). This is
basically for noise performance improvement and signal
level adjustment, which ensures a maximum sensitivity of
the ADC. An 8-bit conversion is then performed, followed
by digital band-pass filtering, to meet the CISPR
normalization and to comply with some additional
limitations met in current applications.
CAUTION
In transmission mode, the receiving part of the circuit is
not disabled and the detection of the transmitted signal
is normally performed. In this mode, the gain chosen
before the beginning of the transmission is stored, and
the AGC is internally set to −6dB as long asDATAIN
is LOW. Then, the old gain setting is automatically
restored.
After digital demodulation, the baseband data signal is
made available after pulse shaping.
The signal pin (RXIN) is a high-impedance input which has
to be protected and DC decoupled for the same reasons
as with pin TXOUT. The high sensitivity (82 dBµV) of this
input requires an efficient 50 Hz rejection filter (realized by
the LC coupling network), which also acts as an
anti-aliasing filter for the internal digital processing;
see Fig.18.
Data format
TRANSMISSION MODE
The data input (DATAIN) is active LOW: this means that a
burst is generated on the line (pin TXOUT) when DATAIN
pin is LOW.
Pin TXOUT is in a high-impedance state as long as the
device is not transmitting. Successive logic 1s are treated
in a Non-Return-to-Zero (NRZ) mode, see pulse shapes in
Figs 8 and 9.
RECEPTION MODE
The data output (pin DATAOUT) is active LOW; this means
that the data output is LOW when a burst is received.
Pin DATAOUT remains LOW as long as a burst is received.
Power-down mode
Power-down input (pin PD) is active HIGH; this means that
the power consumption is minimum when pin PD is HIGH.
Now, all functions are disabled, except clock generation.
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
HANDLING
Inputs and outputs are protected against electrostatic discharge in normal handling. However, to be totally safe, it is
desirable to take normal precautions appropriate to handling MOS devices.
SYMBOL PARAMETER MIN. MAX. UNIT
VDD supply voltage 4.5 5.5 V
fosc oscillator frequency −12 MHz
Tstg storage temperature −50 +150 °C
Tamb ambient temperature −10 +80 °C
Tjjunction temperature −125 °C