CDB4955 Ver la hoja de datos (PDF) - Cirrus Logic

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CDB4955

NTSC/PAL Digital Video Encoder

Cirrus Logic 

CS4954 CS4955

2. ADDITIONAL CS4954/5 FEATURES

• Five programmable DAC output combinations,

including YUV and second composite

• Optional pseudo-progressive scan @ MPEG2

field rates

• Stable color subcarrier for MPEG2 systems

• General purpose input and output pins

• Individual DAC power-down capability

• On-chip color bar generator

• Supports RS170A and ITU R.BT601 compos-

ite output timing

• HSYNC and VSYNC output in ITU R.BT656

mode

• Teletext encoding selectable on two composite

and S-video signals

• Programmable saturation, SCH Phase, hue,

brightness and contrast

• Device power-down capability

• Super White and Super Black support

3. CS4954 INTRODUCTION

The CS4954/5 is a complete multi-standard digital

video encoder implemented in current CMOS tech-

nology. The device can operate at 5 V as well as at

3.3 V. ITU R.BT601- or ITU R.BT656-compliant

digital video input is converted into NTSC-M,

NTSC-J, PAL-B, PAL-D, PAL-G, PAL-H, PAL-I,

PAL-M, PAL-N, or PAL-N Argentina-compatible

analog video. The CS4954/5 is designed to con-

nect, without glue logic, to MPEG1 and MPEG2

digital video decoders.

Two 10-bit DAC outputs provide high quality S-

Video analog output while another 10-bit DAC si-

multaneously generates composite analog video. In

addition, there are three more DACs to provide si-

multaneous analog RGB or analog YUV outputs.

The CS4954/5 will accept 8-bit YCbCr or 8-bit

YUV input data.

The CS4954/5 is completely configured and con-

trolled via an 8-bit host interface port or an I²C

compatible serial interface. This host port provides

access and control of all CS4954/5 options and fea-

tures, such as closed caption insertion, interrupts,

etc.

In order to lower overall system costs, the

CS4954/5 provides an internal voltage reference

that eliminates the requirement for an external, dis-

crete, three-pin voltage reference.

In ISO MPEG-2 system configurations, the

CS4954/5 can be augmented with a common color-

burst crystal to provide a stable color subcarrier

given an unstable 27 MHz clock input. The use of

the crystal is optional, but the facility to connect

one is provided for MPEG-2 environments in

which the system clock frequency variability is too

wide for accurate color sub-carrier generation.

4. FUNCTIONAL DESCRIPTION

In the following subsections, the functions of the

CS4954/5 will be described. The descriptions refer

to the device elements shown in the block diagram

on the cover page.

4.1 Video Timing Generator

All timing generation is accomplished via a

27 MHz input applied to the CLK pin. The

CS4954/5 can also accept a signal from an optional

color burst crystal on the XTAL_IN &

XTAL_OUT pins. See the section, Color Subcarri-

er Synthesizer, for further details.

The Video Timing Generator is responsible for or-

chestrating most of the other modules in the device.

It operates in harmony with external sync input

timing, or it can provide external sync timing out-

puts. It automatically disables color burst on appro-

priate scan lines and automatically generates

serration and equalization pulses on appropriate

scan lines.

DS278F6

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