TDA4650 Datasheet, PDF (9/13 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
TDA4650
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX. UNIT
Super sandcastle pulse detector (note 4)
V₂₄
input voltage pulse levels to
pulse ON
separate V and H blanking pulses _{pulse OFF}
1.3
1.6
1.9
V
1.1
1.4
1.7
V
voltage pulse amplitude
2.0
2.5
3.0
V
input voltage pulse levels to
separate H blanking pulse
pulse ON
pulse OFF
3.3
3.6
3.9
V
3.1
3.4
3.7
V
voltage pulse amplitude
4.1
4.5
4.9
V
input voltage pulse levels to
separate burst gating pulse
pulse ON
pulse OFF
6.2
6.6
7.0
V
6.0
6.4
6.8
V
voltage pulse amplitude
input voltage
during line scan
7.7
−
−
−
V_P
V
1.0
V
I₂₄
input current
during line scan
−
−
−100
µA
Notes to the characteristics
1. For the SECAM 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 the pins 2 and 4 (220 pF each) are matched to the internal resistances of the de-emphasis
network such that every alternate scanned line is blanked.
2. 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.
3. 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.
4. The super sandcastle pulse is compared with three internal threshold levels which are proportional to V_P.
March 1991
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