TDA4651 Datasheet, PDF (9/15 Pages) NXP Semiconductors – Multistandard colour decoder with negative colour difference output signals

Philips Semiconductors
Multistandard colour decoder with negative
colour difference output signals
Preliminary specification
TDA4651
Notes to the characteristics
1. With 20 mV, 3 dB decrease of the output signal is allowed. The level shift at demodulated f₀ relative to blanking level
is less than 5 mV.
2. Burst key width for PAL 4.3 µs, for NTSC 3.6 µs
Burst width for PAL and NTSC 2.25 µs, ratio burst chrominance amplitude 1/2.2.
3. For the SEC+AM standard, amplitude and H/2 ripple content of the CD signals (R−Y) and (B−Y) depend on the
characteristics of the external tuned circuit at pins 7 to 10. The resonant frequency of the external tuned circuit must
be adjusted such that the demodulated f_o voltage level is zero in the −(B−Y) output channel at pin 3.
Now it is possible to adjust the quality of the external circuit such that the demodulated f_o voltage level is zero in the
−(R−Y) output channel at pin 1. If necessary, the f_o voltage level in the −(B−Y) output channel must be readjusted to
zero by the coil of the tuned circuit.
The external capacitors at pins 2 and 4 (each 220 pF) are matched to the internal resistances of the de-emphasis
network such that every alternate scanned line is blanked.
4. Pin 17 open-circuit; proportional to supply voltage.
5. The f_o frequencies of the 8.8 MHz crystal at pin 21, and the 7.2 MHz crystal at pin 19, can be adjusted when the
voltage at pin 17 is less than 0.5 V (burst OFF), thus providing double subcarrier frequencies of the chrominance
signal.
6. Switching voltages for chrominance filters and crystals:
at pin 28 for PAL
at pin 27 for SECAM
at pin 26 for NTSC (3.58 MHz)
at pin 25 for NTSC (4.43 MHz).
7. The inquiry sequence for the standard is: PAL - SECAM - NTSC (3.58 MHz) - NTSC (4.43 MHz). PAL has priority
with respect to SECAM, etc.
8. The super sandcastle pulse is compared with three internal threshold levels which are proportional to V_P.
Table 1 Specification of quartz crystals in HC-49/U13 holder; standard application.
SYMBOL
PARAMETER
VALUE
UNIT
f_n
C_L
∆f_n
R_{dld max}
R_n
C₁
C₀
T
∆f_n
R_r
43221430405 43221430418
nominal frequency
8.867238
7.159090
MHz
load capacitance
20
pF
adjustment tolerance of f_n at +25 °C
in the drive level range between 10^−12 W and 1.0 × 10^−3 W, the 100
resonance resistance may not exceed (at +25 °C) the value of
R_{dld max}
resonance resistance of unwanted response
motional capacitance (±20%)
22
parallel capacitance (±20%)
5.5
operating temperature range
frequency tolerance over temperature range
maximum resonance resistance over temperature range
±40
50
2R_{r (+25 °C)}
19.5
4.4
−10 to +60
±25
60
ppm
Ω
Ω
fF
pF
°C
ppm
Ω
August 1993
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