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PDF TW9920 Data sheet ( Hoja de datos )
| Número de pieza | TW9920 | |
| Descripción | Analog Video Decoder / Encoder | |
| Fabricantes | Techwell | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TW9920 (archivo pdf) en la parte inferior de esta página. Total 70 Páginas | ||
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Techwell, Inc.
www.datasheet4u.com
TW9920 – Analog Video Decoder /
Encoder
Preliminary Data Sheet
Techwell Confidential. Information may change without notice.
Disclaimer
This document provides technical information for the user. Techwell, Inc. reserves the right to
modify the information in this document as necessary. The customer should make sure that they
have the most recent data sheet version. Techwell, Inc. holds no responsibility for any errors that
may appear in this document. Customers should take appropriate action to ensure their use of the
products does not infringe upon any patents. Techwell, Inc. respects valid patent rights of third
parties and does not infringe upon or assist others to infringe upon such rights.
TECHWELL, INC.
1
REV. D
08/29/2005
1 page  
TW9920
Functional Description
www.datasheet4u.com
Figure 1: TW9920 Block Diagram
CIN 0
CIN 1
MUX0
MUX1
MUX2
MUX3
27 Mhz
PDN
PDCLK
PD[9:0]
SCLK
SDAT
U
VY
Y LPF
C LPF
Audio
VD (19:10)
VD(9:0)
HS
VS
CLKx2
FIELD
DVALID
MPOUT
CLKX1
ASCLK
ALRCLK
AMCLK
AMXCLK
CVBS/Y
C
Y
Cb
Cr
TECHWELL, INC.
5
REV. D
08/29/2005
5 Page 
TW9920
www.datasheet4u.com
function can also be used to soften the images. This can be used to provide noise reduction on
noisy signal.
To further enhance the image, a programmable vertical peaking function is provided for up to
+6db of enhancement. A programmable coring level can be adjusted to minimize the noise
enhancement.
The Hue and Saturation
When decoding NTSC signals, TW9920 can adjust the hue of the chroma signal. The hue is
defined as a phase shift of the subcarrier with respect to the burst. This phase shift can be
programmed through a control register.
The color saturation can be adjusted by changing the gain of Cb and Cr signals for all NTSC,
PAL and SECAM formats. The Cb and Cr gain can be adjusted independently for flexibility.
Color Transient Improvement
A programmable Color Transient Improvement circuit is provided to enhance the color
bandwidth. Low level noise enhancement can be suppressed by a programmable coring logic.
Overshoot and undershoot are also removed by special circuit to prevent false color
generation at the color edge.
Power Management
The TW9920 can be put into power-down mode in which its clock is turned off for most of the
circuits. The Y and C path can be separately powered down.
Control Interface
The TW9920 registers are accessed via 2-WIRE SERIAL MPU interface. It operates as a
slave device. Serial clock and data lines, SCL and SDA, transfer data from the bus master at a
rate of 400 Kbits/s. The TW9920 has one serial interface address select pins to program up to
two unique serial addresses TW9920. This allows as many as two TW9920 to share the same
serial bus. Reset signals are also available to reset the control registers to their default values.
Down-scaling and Cropping
The TW9920 provides two methods to reduce the amount of output video pixel data,
downscaling and cropping. The downscaling provides full video image at lower resolution.
Cropping provides only a portion of the video image output. All these mechanisms can be
controlled independently to yield maximum flexibility in the output stream.
TW9920 Down-Scaling
The TW9920 can independently reduce the output video image size in both horizontal and
vertical directions using arbitrary scaling ratios up to 1/16 in each direction. The horizontal
scaling employs a dynamic 6-tap 32-phase interpolation filter for luma and a 2-tap 8-phase
interpolation filter for chroma because of the limited bandwidth of the chroma data. The vertical
scaling uses the simple line dropping method. It is recommended to choose integer vertical
scaling ratio for best result.
TECHWELL, INC.
11
REV. D
08/29/2005
11 Page | ||
| Páginas | Total 70 Páginas | |
| PDF Descargar | [ Datasheet TW9920.PDF ] | |
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