Application Note 1943: 2003 Improving Performance MAX4455 Reducin
|
|
|
Top Searches for this datasheet
CONVERSION/SAMPLING CIRCUITS VIDEO CIRCUITS
Application Note 1943: 2003
Improving Performance MAX4455 Reducing On-Screen Display Artifacts This article describes applications circuit MAX4455 Arbitrary Graphics OnScreen Display Video Generator reduce effects finite switching time insertion graphics onto video signal.
This application note describes circuit modification MAX4455 board that will improve performance MAX4455/MAX4358 chip reducing on-screen display (OSD) artifacts caused finite switch time effects. This modification included similar MAX4455/MAX4358 application circuit yielding same performance improvements. MAX4455 8-channel arbitrary graphics generator MAX4358 32x16 crosspoint switch with integrated fast insertion. Explanation Finite Switch Time Effect MAX4455 there outputs involved generation graphics: first output, OSDFILL, analog representation video fill signal, second output, OSDKEY, digital signal that controls turn turn fast switch. They synchronized within nanosecond output MAX4455. finite switching time fast MAX4358, OSDFILL signal emerges slightly delayed from OSDKEY signal. This results slightly delayed OSDFILL graphic with trailing black level IRE) equal width switch delay time shown Figure This effect objectionable applications that display white characters, high contrast between white character trailing black edge. This even more obvious light background light dark light pattern.
www.maxim-ic.com/an1943
Page
Figure Finite switch time effect
Circuit Solution With circuit modification shown Figure trailing black level will replaced with trailing white level. this white level equals OSDFILL level then trail effectively disappears, eliminating finite switch time effect. This shown Figure resistor divider formed sets brightness trailing white level, which equal brightness OSDFILL. When equals ohms, then trailing white level nominally IRE. Figure shows modification only eight channels. Four MAX4616s used improve eight channels MAX4455.
www.maxim-ic.com/an1943
Page
Figure Modification MAX4455 circuit board channel
www.maxim-ic.com/an1943
Page
Figure finite switch time effect
MORE INFORMATION MAX4358: QuickView Full (PDF) Data Sheet (1.0M) Free Sample MAX4455: QuickView Full (PDF) Data Sheet (672k) Free Sample MAX4616: QuickView Full (PDF) Data Sheet (176k) Free Sample
www.maxim-ic.com/an1943
Page
Other recent searches
TB6596FLG - TB6596FLG TB6596FLG Datasheet
ST722BM6XX - ST722BM6XX ST722BM6XX Datasheet
MAX2057 - MAX2057 MAX2057 Datasheet
KST4401 - KST4401 KST4401 Datasheet
ACTF474 - ACTF474 ACTF474 Datasheet
Privacy Policy | Disclaimer
© 2012 Datasheet Archive
