tw9910 ETC-unknow, tw9910 Datasheet - Page 5

• Manufacturer Part Number: tw9910
• Description: Power Ntsc/pal/secam Video Decoder With Slicer
• Manufacturer: ETC-unknow

TW9910
Introduction
Analog Front End
Sync Processor
Y/C separation
TECHWELL, INC.
The TW9910 is a low power NTSC/PAL/SECAM video decoder chip that is designed for portable
applications. It consumes less than 100mW in typical composite input application. The available power
down mode further reduces the power consumption. It uses the 1.8V for both analog and digital supply
voltage and 3.3V for I/O power. A single 27MHz crystal is all that needed to decode all analog video
standards.
The video decoder decodes the base-band analog CVBS or S-video signals into digital 8 or 16-bit 4:2:2
YCbCr for output. It consists of analog front-end with input source selection, variable gain amplifier and
analog-to-digital converters, Y/C separation circuit, multi-standard color decoder (PAL BGHI, PAL M,
PAL N, combination PAL N, NTSC M, NTSC 4.43 and SECAM) and synchronization circuitry. The Y/C
separation is done with high quality adaptive 4H comb filter for reduced cross color and cross
luminance. The advanced synchronization processing circuitry can produce stable pictures for non-
standard signal as well as weak signal. A video scaler is provided to arbitrarily scale down the output
video in a packed format. The output of the decoder is line-locked and formatted to the ITU-R 656
output with embedded sync.
The TW9910 also includes circuits to detect and process vertical blanking interval (VBI) signal. It slices
and process VBI data for output through video bus. Some information can also be alternatively
retrieved through host interface. It also detects copy-protected signal according to Macrovision
standard including AGC and colorstripe pulses.
A 2-wire serial host interface is used to simplify system integration. All the functions can be controlled
through this interface.
The analog front-end prepares and digitizes the AC coupled analog signal for further processing. Both
channels have built-in anti-aliase filter and 10-bit over-sampling ADCs. The characteristic of the filter is
available in the filter curve section. The Y channel has additional 4-input multiplexer, and a variable
gain amplifier for automatic gain control (AGC). It can support a maximum input voltage range of 1.4V
without attenuation. The C channel has only one input with built-in clamping circuit that restores the DC
level. Software selectable analog inputs allow two possible input combinations:
The sync processor of TW9910 detects horizontal synchronization and vertical synchronization signals
in the composite video or in the Y signal of an S-video or component signal. The processor contains a
digital phase-locked-loop and decision logic to achieve reliable sync detection in stable signal as well as
in unstable signals such as those from VCR fast forward or backward. It allows the sampling of the
video signal in line-locked fashion.
For NTSC and PAL standard signals, the luma/chroma separation can be done either by adaptive
comb filtering or notch/band-pass filter combination. For SECAM standard signals, only notch/band-
pass filter is available. The default selection for NTSC/PAL is comb filter. The characteristics of the
band-pass filter are shown in the filter curve section.
1. Four selectable composite video inputs.
2. Three selectable composites and one S-video input.
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Low Power NTSC/PAL/SECAM
Video Decoder with VBI Slicer
09/21/2006
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