BT856 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

BT856

YCrCb or RGB to NTSC/PAL Digital Video Encoder

Unspecified 

Bt856/7

CIRCUIT DESCRIPTION

Internal Color Bars

Internal Color Bars

The Bt856/7 can be configured to generate 75% amplitude, 100% saturation

(75/7.5/75/7.5 for NTSC/PAL–M with setup; 75/0/75/0 for PAL) color bars, re-

gardless of the GAMMA* pin state.

If the IIC DATA pin is held high during the rising edge of RESET*, color bars

are automatically enabled. Otherwise, following a reset, colorbars can be enabled

or disabled by writing a one or a zero into bit D4 of register 0xDE. With the excep-

tion of the YCMODE and GAMMA* pins, all pins and registers can be changed

and reprogrammed while generating color bars, thereby simplifying testing of var-

ious modes.

If the IIC DATA pin is held low while the RESET* pin goes high, color bars will

not be generated following a reset condition. The IIC DATA pin is normally high,

unless performing a data transfer or acknowledge pulse.

SCART/PeriTV Support

The RGBOUT pin may be used to configure the Bt856/7 to generate analog RGB

video signals (rather than S-video) to interface to a SCART/PeriTV connector.

When RGBOUT = 1, red information is output on the C/R pin, blue information is

output on the CVBS/B pin, and green information is output on the CVBS/G pin.

Composite video will be present on the Y/CVBS DAC, but will not be time-aligned

with RGB outputs. In RGB mode, nominal RGB amplitude is 635 mVpp with a

37.5 Ω load, while in YC mode, RGB outputs are 700 mVpp into 37.5 ohms.

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