February 1994

13

Philips Semiconductors

Product specification

PAL/NTSC decoder

TDA3566A

8. These signal amplitudes are determined by the ACC circuit of the reference part.

9. This value depends on the gain setting of the RGB output amplifiers and the drift of the picture tube guns. Higher

black level values are possible (up to 5 V) however, in that condition the amplitude of the available output signal is

reduced.

10. The variation of the black-level during brightness control in the three different channels is directly dependent on the

gain of each channel. Discolouration during adjustments of contrast and brightness does not occur because

amplitude and the black-level change with brightness control are directly related.

11. With respect to the measuring pulse.

12. This difference occurs when the source impedance of the data signals is 150

Ω and the black level clamp pulse width

is 4

µs (sandcastle pulse). For a lower impedance the difference will be lower.

13. For correct operating of the black level stabilization loop, the leading and trailing edges of the sandcastle pulse

(measured between 1.5 V and 3.5 V) must be within 200 ns and 600 ns respectively.

14. The voltage at pins 24 and 25 can be changed by connecting the load resistors (20 k

Ω, 1%, in this condition) to the

slider bar of the hue control potentiometer (see Fig.6). When the transistor is switched on, the voltage at pins 24 and

25 is reduced below 9 V, and the circuit is switched to NTSC mode. The width of the burst gate is assumed to be

4

µs typical.