TDA8844 datasheet(47/68 Pages) PHILIPS

47 / 68 page

December 16, 1997

Philips Semiconductors

Tentative Device Speciﬁcation

I2C-bus controlled PAL/NTSC/SECAM TV

processors

TDA884X/5X-N2 series

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 I2C subaddress 19. The ACL circuit reduces the gain of

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 f0 = 4.433619 or 3.579545 MHz; CL = 20 pF.

b) Motional capacitance CM = 20.5 fF (4.43 MHz crystal) or 14.5 fF (3.58 MHz crystal).

c) Parallel capacitance C0 = 5.0 pf for both X-tals.

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 = CM /(1 + C0/CL)2

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.

TDA8844 Datasheet(PDF) 47 Page - NXP Semiconductors

TDA8844 Datasheet(HTML) 47 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

Datasheet Download

Link URL