Hitachi C1421R User Manual

This compensates for the storage time of the horizontal deflection transistor.
The a>- 2 loop filter (C) is externally connected to pin 42.
The horizontal phase can be given a static off set via 12C-bus (HSH "horizontal shift'')
A dynamic correction is possible by current feedback into the a>- 2 /oop fi/ter capacitar.
To protect the horizontal deflection transistor, the horizontal drive is switched off immediately when a power
failure (" Power-On Reset" bit POR) is detected.
The power failure may have corrupted the contents of the internal data registers, so the TDA8374 should be
started up again.
The TDA837 4 has a separate supply input (pin 37) that is only used as a clean supply vo/tage for the horizontal
oscillator circuits.
Vertical synchronization
The vertical sawtooth generator drives the vertical output.
lt uses an externa/ capacitar at pin 51 anda current reference resistor at pin 52.
The TDA8374 vertical drive has differential current outputs for DC-coupled vertical output stage, like the TDA8356.
At TDA8356 input pins I and 2 this current is converted into a drive voltage via a resisto r
Geometry processing
With the TDA8374 it is possible to implement automatic geometry a/ignment, because ali parameters are adjusted
via the 12C bus.
The deflection processar of the TDA837 4 offers the following five contrais;
- Horizontal shift
-Vertical slope.
- Vertical amplitude
-Vertical 8-correction
-
vertical shift
Colou r decoder
The colour decoder contains an alignment-free X-tal oscillator, a dual killer circuit and co/our difference demodu/ators.
Together with the TDA8395 SECAM add-on a multi standard PAUSECAM/NTSC decoder can be built with
automatic recognition.
Which standard can be decoded depends on the externa/ Xtals used.
Two Xtal pins (34and 36) are present so normally no externa/ switching is required.
The I. C. must be to/d which X-tais are connected (bits XA and XB).
This is important, because the X-tal frequency of the colour decoder is also used to calibrate many internal circuits.
The burst phase detector locks the Xtal oscillator with the chroma burst signal.
The phase detector operates duríng the burst key períod only, to prevent dísturbance of the PLL by the chroma sígnal.
Two gain modes provide:
- Good catching range when the PLL is not Locked.
- Low ripple voltage and good noise immunity once the PLL has locked
The killer circuit switches-off the R-Y and 8-Y demodulators at very /ow input signal conditions (chroma burst amplitude).
A hysteresis prevents on/off switching at low, noisy signals.
Color standard pin34 pin35 XA
XB
PAL4.43/SECAM + NTSC-4.43 none 4.43
1
o
PAL4.43/SECAM + NTSC-M 3.58 4.43
1 1
9-UK

Hitachi C1421R Specifications

General

Brand	Hitachi
Model	C1421R
Category	TV
Language	English