AL128 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

AL128

Plug and Play VGA to NTSC/PAL Converter

Unspecified 

AL128

6.0 Functional Description

The AL128 accepts either analog RGB or digital RGB data. The analog RGB data is digitized by

three 50MHz 8-bit video A/D converters and is converted into 24-bit digital RGB data. For graphic

controllers with standard or proprietary digital RGB output such as a high-color feature connector,

VAFC, or flat panel interface, the optional 24-bit digital RGB interface provides a solution for

optimal video quality.

The 24-bit digital RGB is passed to the digital processing unit of the chip. This DSP unit performs

scan conversion operations and other digital signal processing such as flicker filtering, YUV filtering,

scaling and color space conversion in the digital domain. The processed video data is sent to the

digital TV encoder for converting into broadcast quality composite and S-video signals or original

RGB format, which are in turn converted by three 9-bit D/A converters into analog outputs.

Functions can be controlled by dedicated hardware pins as well as software. The I2C interface

provides full software programmability. The aforementioned hardware and software programmability

also applies to the power-down feature. Alternatively only four push buttons are required to control

the major functions such as sharpness, pan, zoom, brightness, color bar output and position centering

without the use of software or microcontroller.

6.1 Input Interface

RGB data and horizontal and vertical sync signals of the VGA controller are used as inputs. Analog

RGB data or 24-bit digital RGB data are both supported. The analog R, G, B signals are digitized

with three built-in 8-bit A/D converters. The voltage swing of VGA RGB signals is typically 0.7

volts. The VRT and VRB pins set the input voltage references of the A/D converters. When digital

RGB data is used as the input, the internal A/D converters can be disabled by setting pin ADEN low,

which may significantly reduce the power consumption.

Digital inputs for the AL128 can be either 24-bit RGB 888 or 16-bit RGB 565. RGB 565 can in turn

be in VAFC or feature connector format. The INTYPE pins of the AL128 have to be set correctly

to match the different applications.

INTYPE <1:0>

Pin 156, pin 157

00

01

10

11

Digital Graphic Input Type

24-bit RGB

Reserved

Feature connector (RGB565)

VAFC (RGB565)

April 2, 1999

12

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