
1999 Sep 28
122
Philips Semiconductors
Preliminary Device Specification
TV signal processor-Teletext decoder with
embedded
μ
-Controller
TDA935X/6X/8X series
20. This figure is independent of the TV standard and valid for a frequency deviation of
±
25 kHz at a carrier frequency
of 4.5 MHz or a deviation of
±
50 kHz at a carrier frequency of 5.5/6.0/6.5 MHz.
21. The deemphasis pin can also be used as additional audio input. In that case the internal (demodulated FM signal)
must be switched off. This can be realised by means of the SM (sound mute) bit. When the vision IF amplifier is
switched to positive modulation the signal from the FM demodulator is automatically switched off. The external signal
on pin 28 must be switched off when the internal signal is selected.
22. f = 5.5 MHz; FM: 1 kHz,
±
17.5 kHz deviation. Measured with a bandwidth of 15 kHz and the audio attenuator at
6
dB.
23. f = 4.5 MHz, FM: 1 kHz,
±
100 kHz deviation and the volume control setting such that no clipping occurs in the audio
output.
24. Unweighted RMS value, Vi = 100 mV
RMS
, FM: 1 kHz,
±
50 kHz deviation, audio attenuator at
6 dB.
25. Audio attenuator at
20 dB; temperature range 10 to 50
°
C.
26. In various versions the Automatic Volume Levelling (AVL) function can be activated. The pin to which the external
capacitor has to be connected depends on the IC version. For the 90
°
types the capacitor is connected to the EW
output pin (pin 20). For the 110
°
types a choice can be made between the AVL function and a sub-carrier output /
general purpose switch output. The selection must be made by means of the CMB0 and CMB1 bit in subaddress
22H (see also table G-1 on page G-9). More details about the sub-carrier output are given in the parameters D.10.
The Automatic Volume Levelling (AVL) circuit stabilises automatically the audio output signal to a certain level which
can be set by means of the volume control. This AVL function prevents big audio output fluctuations due to variation
of the modulation depth of the transmitter. The AVL can be switched on and off via the AVL bit in subaddress 29H.
The AVL is active over an input voltage range (measured at the deemphasis output) of 150 to 1500 mV
RMS
. The AVL
control curve is given in Fig.51. The control range of +6 dB to
14 dB is valid for input signals with 50% of the
maximum frequency deviation.
27. Signal with negative-going sync. Amplitude includes sync pulse amplitude.
28. This parameter is measured at nominal settings of the various controls.
29. Indicated is a signal for a colour bar with 75% saturation (chroma : burst ratio = 2.2 : 1).
30. The contrast and saturation control is active on the internal signal (YUV) and on the external RGB/YUV input. The
Text/OSD input can be controlled on brightness only. Nominal contrast is specified with the DAC in position 20 HEX.
Nominal saturation as maximum
10 dB.
31. The YUV input signal amplitudes are based on a colour bar signal with 75% saturation.
32. When the decoder is forced to a fixed subcarrier frequency (via the CM-bits) the chroma trap is always switched-on,
also when no colour signal is identified. In the automatic mode the chroma trap is switched-off when no colour signal
is identified.
33. Valid for a signal amplitude on the Y-input of 0.7 V black-to-white (100 IRE) with a rise time (10% to 90%) of 70 ns
and the video switch in the Y/C mode. During production the peaking function is not tested by measuring the
overshoots but by measuring the frequency response of the Y output.
34. For video signals with a black level which deviates from the back-porch blanking level the signal is “stretched” to the
blanking level. The amount of correction depends on the IRE value of the signal (see Fig.52). The black level is
detected by means of an internal capacitor. The black level stretcher can be switched on and off via the BKS bit in
subaddress 2DH. The values given in the specification are valid only when the luminance input signal has an
amplitude of 1 V
p-p
.
35. The slicing level is independent of sync pulse amplitude. The given percentage is the distance between the slicing
level and the black level (back porch). When the amplitude of the sync pulse exceeds the value of 350 mV the sync
separator will slice the sync pulse at a level of 175 mV above top sync. The maximum sync pulse amplitude is 4 V
p-p
.