TW2864D datasheet(13/110 Pages) RENESAS

13 / 110 page

TW2864

FN7745 Rev. 0.00

Page 13 of 110

September 28, 2012

Automatic Gain Control and Clamping

All four analog channels have built-in clamping circuit that restores the signal DC level. The Y channel restores the

back porch of the digitized video to a level of 60. This operation is automatic through internal feedback loop. The

Automatic Gain Control (AGC) of the Y channel adjusts input gain so that the sync tip is at a desired level.

Programmable white peak protection logic is included to prevent saturation in the case of abnormal signal proportion

between sync and white peak level.

Sync Processing

The sync processor of TW2864 detects horizontal synchronization and vertical synchronization signals in the

composite video or in the Y signal of an S-video or component signal. The processor contains a digital phase-locked-

loop and decision logic to achieve reliable sync detection in stable signal as well as in unstable signals such as those

from VCR fast forward or backward.

The vertical sync separator detects the vertical synchronization pattern in the input video signals. In addition, the

actual sync determination is controlled by a detection window to provide more reliable synchronization. An option is

available to provide faster responses for certain applications. The field status is determined at vertical

synchronization time. The field logic can also be controlled to toggle automatically while tracking the input

TW2864D Datasheet(PDF) 13 Page - Renesas Technology Corp