BT856 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

BT856

YCrCb or RGB to NTSC/PAL Digital Video Encoder

Unspecified 

Bt856/7

CIRCUIT DESCRIPTION

Video Timing

Noninterlaced Operation

The device can be operated in noninterlaced mode by setting the INTERLACE pin

to a logical zero. When in noninterlaced master mode, the Bt856/7 always displays

the odd-field, meaning that the falling edges of HSYNC* and VSYNC* will be

output coincidentally. FIELD will change state with each VSYNC* edge. Addi-

tionally, a 30 Hz offset will be subtracted from the color subcarrier frequency

while in NTSC/PAL–M mode so that the color subcarrier phase will be inverted

from field to field. Subcarrier phase is reset to zero upon rising RESET* and every

4 fields of NTSC/PAL–M or 8 fields of PAL–B, D, G, H, I, N, N-Argentina, unless

bit D3 in register 0xDE is a logical one.

Transition from interlaced to noninterlaced in master mode, occurs during odd

fields to prevent synchronization disturbance. In slave mode, transition occurs af-

ter a subsequent falling edge of VSYNC*.

NOTE: Consumer VCRs can record noninterlaced video with minor noise arti-

facts, but special effects (e.g., scan > 2x) may not function properly.

Power-Down Mode

In power-down mode (SLEEP pin set to 1), register states are preserved, but other

chip functionality (including I2C communication) is disabled.

This mode should be set when the Bt856/7 may be subjected to clock and data

frequencies outside its functional range.

Brooktree®

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