Sharp 32LF-94EC, Service Manual, Page: 27 / 82

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AK53 D.O.C. Service Manual 22/03/2004
_ Two YUV / RGB inputs, which can handle also YPrPb and sync on Y for DVD players Also 2Fh YUV /
RGB signals can be handled by the A/D converters.
_ An audio stereo crossbar switch with two outputs (one stereo, one stereo or mono) for further
processing in the processor after A/D conversion and three stereo outputs for external connections.
Extra inputs are provided to enable also the selection of demodulated RF sound (mono, NICAM, 2CS)
from the Digital TV Signal Processor for use on external connections.
_ Low pass filtering and A/D conversion. The audio and video sampling clocks use the same reference
so it is possible to interleave video and audio data into one serial data stream.
_ For control, I 2 C control is built-in with a selectable address.
_ Auxiliary building blocks which perform some functions which have typical better performance in
analogue design environment than in digital and are used by the Digital TV Signal Processor:
- Reference voltage for vertical deflection and audio ADC's
- Voltage to current conversion of the E/W
The set-up with an analogue and a digital part has the following advantages:
_ High frequent parts (IF) can be included in the concept
_ Less A/D and D/A converters needed for source switching
_ Better performance for AD converters (realized in analogue design environment, more accurate, less
tolerance)
_ Critical items like reference voltages can be realized in the analogue environment
4.DIGITAL TV PROCESSOR (PNX300X (CALLED AS ADOC))
The DOC system serves the TV functionality for small signal processing of audio, video, VBI services,
graphics and control. This chip implements all TV functions in digital technology. PNX300X is the digital
TV processor which consists of;
?
TV video processor
?
TV deflection processor
?
TV audio processor
?
TV microcontroller
As it is shown in the below block diagram ADOC gets the digital signal which is converted by MPIF and
processed in its own blocks and controls the overall system by I2C and the software programme is
downloaded into a flash memory which tells microcontroller within ADOC about the software
management and the output of ADOC turns into RGB, Main/Headphone audio right/left.
Then RGB output of ADOC is processed into a RGB preamplifier circuit to get enough gain for the video
output amplifier TDA6108JF (in CRT board)
Highlight points of ADOC:
(1)-Digital (I2D) data link is connected from MPIF to ADOC with a swing of about 300mV. The data rate
is 594Mbit/s.
(2)-Only one crystal is used in overall system which is 13.5MHZ.