TDA9144 View Datasheet(PDF) - Philips Electronics

Part Name

Description

MFG CO.

TDA9144

I2C-bus controlled, alignment-free PAL/NTSC/SECAM decoder/sync processor with PALplus helper demodulator

Philips Electronics 

Philips Semiconductors

I2C-bus controlled, alignment-free PAL/NTSC/SECAM

decoder/sync processor with PALplus helper demodulator

Preliminary specification

TDA9144

handbook, full pagewidth

c

PAL

KILLED

NTSC

c

c

PAL

SECAM

c

SECAM c

KILLED

c

NTSC

KILLED

c

PAL

KILLED

Reference crystal

PAL

KILLED

c

c NTSC

KILLED

PAL

c

c

NTSC

Second crystal

MGE040

Fig.3 Search loop of the identification circuit.

Integrated filters

All chrominance bandpass and notch filters, including the

luminance delay line, are an integral part of the IC. The

filters are gyrator-capacitor type filters. The resonant

frequency of the filters is controlled by a circuit that uses

the active crystal to tune the SECAM Cloche filter during

the vertical flyback time. The remaining filters and the

luminance delay line are matched to this filter. The filters

can be switched to either 4.43 MHz, 4.29 MHz or

3.58 MHz. The switching is controlled by the standard

identification circuit. The luminance notch used for

SECAM has a lower Q-factor than the notch used for

PAL/NTSC. The notches are provided with a little preshoot

to obtain a symmetrical step response. In Y/C mode the

chrominance notch filters are bypassed, to preserve full

signal bandwidth. For a CVBS signal the chrominance

notch filters can be bypassed by bus selection of bit TB

(trap bypass).

The luminance to helper delay difference can be adjusted

by I2C-bus, to achieve a correct fitting for the delay in the

PALplus helper demodulation signal path and the

luminance path (not for helper only with trap). The delay of

the colour difference signals −(R−Y) and −(B−Y) in the

chrominance signal path and the external chrominance

delay lines when used, can be fitted to the luminance

signal delay control via I2C-bus in 40 ns steps.

The typical luminance delay can be calculated:

delay ≈ 90 + SAK⋅SBK {170 + 40(FRQ⋅TB)} + 160(YD3) +

160(YD2) + 80(YD1) + 40(YD0) [ns].

1996 Jan 17

7

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