TDA8841

Manufacturer Part NumberTDA8841
DescriptionI2C-bus controlled PAL/NTSC TV processor
ManufacturerPhilips Semiconductors
TDA8841 datasheet
 


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Philips Semiconductors
2
I
C-bus controlled PAL/NTSC/SECAM TV
processors
39. The IC’s have a zoom adjustment possibility for the horizontal and vertical deflection. For this reason an extra DAC
has been added in the vertical amplitude control which controls the vertical scan amplitude between 0.75 and 1.38
of the nominal scan. At an amplitude of 1.05 of the nominal scan the output current is limited and the blanking of the
RGB outputs is activated. This is illustrated in Fig.21. In addition to the variation of the vertical amplitude a vertical
scroll function is introduced so that it is always possible to display the most important part of the picture.
The nominal scan height must be adjusted at a position of 19 HEX of the vertical “zoom” DAC and 1F HEX of the
vertical scroll DAC.
40. At a chrominance input voltage of 660 mV (p-p) (colour bar with 75% saturation i.e. burst signal amplitude
300 mV (p-p)) the dynamic range of the ACC is +6 and 20 dB.
41. The ACL function can be activated by via the ACL bit in the I
the chroma amplifier for input signals with a chroma-to-burst ratio which exceeds a value of 3.0.
42. All frequency variations are referenced to 3.58 or 4.43 MHz carrier frequency.
All oscillator specifications are measured with the Philips crystal series 9922 520 with a series capacitance of 18 pF.
The oscillator circuit is rather insensitive to the spurious responses of the X-tal. As long as the resonance resistance
of the third overtone is higher than that of the fundamental frequency the oscillator will operate at the right frequency.
The typical crystal parameters for the X-tals mentioned above are:
a) Load resonance frequency f
b) Motional capacitance C
= 20.5 fF (4.43 MHz crystal) or 14.5 fF (3.58 MHz crystal).
M
c) Parallel capacitance C
= 5.0 pf for both X-tals.
0
The minimum detuning range can only be specified if both the IC and the X-tal tolerances are known and therefore
the figures regarding catching range are only valid for the specified X-tal series. In this figure tolerances of the X-tal
with respect to the nominal frequency, motional capacitance and ageing have been taken into account and have
been counted for by gaussic addition.
Whenever different typical X-tal parameters are used the following equation might be helpful for calculating the
impact on the tuning capabilities:
Detuning range = C
/(1 + C
M
0
The resulting detuning range should be corrected for temperature shift and supply voltage deviation of both the IC
and the X-tal. To guarantee a catching range of 300 Hz on 4.43 MHz the minimum motional cpacitance of the X-tal
must have a value 13.2 fF or higher. For a catching range of 250 Hz with the 3.58 MHz X-tal the minimum motional
cpacitance must have a value of 9 fF.
The actual series capacitance in the application should be CL = 18 pF to account for parasitic capacitances on and
off chip.
For 3-norma applications with 2 X-tals connected to one pin the maximum parasitic capacitance of the X-tal pin
should not exceed 15 pF.
43. Because the base-band delay line is integrated the demodulated colour difference signals are matrixed before they
are supplied to the outputs. The colour difference out- and inputs must be dc coupled.
44. This parameter indicates the bandwidth of the complete chrominance circuit including the chrominance bandpass
filter. The bandwidth of the low-pass filter of the demodulator is approximately 1 MHz.
45. The subcarrier output signal can be used as reference signal for external comb filter IC’s (e.g. SAA 4961). When the
CMB bit is low the subcarrier signal is suppressed and the dc level is low. With the CMB bit high the output level is
high and the subcarrier signal is present.
46. The Dynamic Skin Tone Correction circuit is designed such that it corrects (instantaneously and locally) the hue of
those colours which are located in the area in the UV plane that matches to skin tones. The correction is dependent
on the luminance, saturation and distance to the preferred axis and can be realised for 2 different angles. This angle
can be set by means of the DSA bit. Because the amount of correction is dependent on the parameters of the
incoming YUV signal it is not possible to give exact figures for the correction angle. The correction angle of 45
(+/-22.5) degrees is just given as an indication and is valid for an input signal with a luminance signal amplitude of
75% and a colour saturation of 50%. A graphical representation of the control behaviour is given in Fig.20.
December 16, 1997
2
C subaddress 19. The ACL circuit reduces the gain of
= 4.433619 or 3.579545 MHz; C
0
2
/C
)
L
47
Tentative Device Specification
TDA884X/5X-N2 series
= 20 pF.
L