TDA8366 Philips Semiconductors, TDA8366 Datasheet - Page 31

• Manufacturer Part Number: TDA8366
• Description: I2C-bus controlled PAL/NTSC TV processor
• Manufacturer: Philips Semiconductors

Philips Semiconductors
22. The timing pulses for the vertical ramp generator are obtained from the horizontal oscillator via a divider circuit. This
23. Conditions: frequency is 50 Hz; normal mode; VS = 1F.
24. At a chrominance input voltage of 660 mV (p-p) (colour bar with 75% saturation i.e. burst signal amplitude
25. All frequency variations are referenced to 3.58 or 4.43 MHz carrier frequency.
January 1995
I
processor
2
divider circuit has 3 modes of operation:
a) Search mode ‘large window’.
This mode is switched on when the circuit is not synchronized or when a non-standard signal (number of lines per
frame in the 50 Hz mode is between 311 and 314 and in the 60 Hz mode between 261 and 264). In the search mode
the divider can be triggered between line 244 and line 361 (approximately 45 to 64.5 Hz).
b) Standard mode ‘narrow window’.
This mode is switched on when more than 15 succeeding vertical sync pulses are detected in the narrow window.
When the circuit is in the standard mode and a vertical sync pulse is missing the retrace of the vertical ramp generator
is started at the end of the window. Consequently, the disturbance of the picture is very small. The circuit will switch
back to the search window when, for 6 successive vertical periods, no sync pulses are found within the window.
c) Standard TV-norm (divider ratio 525 (60 Hz) or 625 (50 Hz).
When the system is switched to the narrow window it is checked whether the incoming vertical sync pulses are in
accordance with the TV-norm. When 15 standard TV-norm pulses are counted the divider system is switched to the
standard divider ratio mode. In this mode the divider is always reset at the standard value even if the vertical sync
pulse is missing.
When 3 vertical sync pulses are missed the system switches back to the narrow window and when also in this
window no sync pulses are found (condition 3 missing pulses) the system switches over to the search window.
The vertical divider needs some waiting time during channel-switching of the tuner. When a fast reaction of the
divider is required during channel-switching the system can be forced to the search window by means of the NCIN bit
in subaddress 08.
300 mV (p-p)) the dynamic range of the ACC is +6 and 20 dB.
All oscillator specifications are measured with the Philips crystal series 9922 520.
If the spurious response of the 4.43 MHz crystal is lower than 1 dB with respect to the fundamental frequency for a
damping resistance of 1 k , oscillation at the fundamental frequency is guaranteed.
The spurious response of the 3.58 MHz crystal must be lower than 1 dB with respect to the fundamental frequency
for a damping resistance of 1.5 k .
The catching and detuning range are measured for nominal crystal parameters. These are:
a) Load resonance frequency f
b) Motional capacitance C
c) Parallel capacitance C
The actual load capacitance in the application should be C
off chip.
Philips Components has developed a special crystal which is tuned to the correct frequency in an application without
series capacitance (code number 9922 520 0038X; see Table 43). This has the advantage that the tuning (catching)
range is increased with approximately 50% without negative effects on spurious responses. When the catching range
of 300 Hz is considered too low this special crystal is a suitable alternative.
The free-running frequency of the oscillator can be checked by opening the colour PLL via the I
condition the colour killer is not active so that the frequency off-set is visible on the screen. When two crystals are
connected to the IC the circuit must be forced to one of the crystals during this test to prevent the oscillator switching
continuously between the two frequencies.
C-bus controlled PAL/NTSC TV
0
1
= 5.5 pF (4.43 MHz crystal) or 4.5 pF (3.58 MHz crystal).
= 20.6 fF (4.43 MHz crystal) or 14.7 fF (3.58 MHz crystal).
0
= 4.433619 or 3.579545 MHz; C
31
L
= 18 pF to account for parasitic capacitances on and
L
= 20 pF.
Objective specification
2
C-bus. In that
TDA8366