ViewSonic VS11770-1M, Service Manual

Page: 27 / 100

C. DTV and HDMI.
MT5112 is a fully integrated single-chip 8-VSB and 64/256-QAM demodulator. The chip is
designed specifically for the digital terrestrial HDTV and CATV receivers . MT5112 includes a
10-bit A/D converter, 8-VSB/QAM demodulator, TCM (Trellis-Coded modulation) decoder,
and Reed- Solomon Forward Error Correction decoder. Moreover, an internal controller
handles the acquisition and tracking to ensure the best receiving performance.
The internal controller communicates with the external host controller via the I2C-compatible
interface, and also provides direct control to the RF tuner via the second I2C-compatible
interface.
MT5112 accepts either the direct IF signals and the IF signals are sampled by a 10-bit A/D
converter. Afterward, the digitized samples are further processed for adjacent channel
interference rejection. MT5112 measures the power level of the digitized sequence, and feeds
the control voltages back to the RF tuner and the IF amplifier respectively. The control
voltages are converted to analog signals through the on-chip 1-bit sigma-delta D/A converters
plus the off-chip R-C low-pass filters. The automatic gain control keeps the received power
level at a desired level and maximizes the received SNR.
The MT5371 includes a DTV Backend Decoder SOC which support flexible transport demux,
HD MPEG-2 video decoder, JPEG decoder, MPEG1,2, MP3, AC3 audio decoder.
It incorporates a processor for system control. The processor issues instructions to control the
peripheral via I²C. DDR
SDRAM is externally connected to the MT5371, the unified memory
allows all internal decoders can share data, which reduces external memory types and
capacities.
MT5371 is also including a fully HDMI-compliant receiver that fits directly into home theater
products such as LCD TVs, plasma TVs and HDTVs. The receiver is capable of supporting
ViewSonic Corporation
Confidential - Do Not Copy
N
3235
w-1M
24