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Altera_Forum
Honored Contributor
Honored ContributorEmulated LVDS ?
Hi forum, this is my first post.
I'm trying to use a laptop lcd screen with the De0-nano board (fpga:EP4CE22F17C6), and i have some questions about lvds and emulated lvds: What's the difference between LVDS and Emulated LVDS? Why do i have to use a external resistor network? Is it necessary? How could i damage the LVDS or the Emulated LVDS?, What cautions must i take? My laptop's lcd datasheet says the LVDS signal must be between +100mv and -100mv, why do i get +3.3 and -3.3 in the fpga's LVDS pins when i measure them? Does it matter or LVDS just looks for the current direction? thank you for your help,and time sherneyko1 Reply
Altera_Forum--- Quote Start --- My laptop's lcd datasheet says the LVDS signal must be between +100mv and -100mv --- Quote End --- This sounds like a minimal specification. LVDS standards require a differential voltage of 200 or 250 to 450 mV. But in any case, LVDS spells low voltage differential signalling. --- Quote Start --- Why do i have to use a external resistor network? Is it necessary? --- Quote End --- It necessary to achieve the specified voltage range. --- Quote Start --- why do i get +3.3 and -3.3 in the fpga's LVDS pins when i measure them? --- Quote End --- LVDS signals are terminated with a 100 ohm resistor. You get the expected voltage with this termination. --- Quote Start --- What's the difference between LVDS and Emulated LVDS? --- Quote End --- Besides requiring the said resistor network, emulated LVDS is slower than dedicated LVDS drivers. Consult the FPGA device manual for the exact specification..
