TFT modules with _minimum_ clock frequency spec

I have been looking around for a TFT module for a design (5" to 8" sized,

800x480 min.,thin) and found some really good looking. The problem I have is that some of them specify a minimum dot clock frequency, typically well above 25 MHz. Now apart from a PLL they may have inside the module I can think of little reasons why they need that; and I have not heard of such a thing, but I am far from the insides of these (hence my posting :-). I could pretty well live at a 30 Hz or even 20 Hz frame rate, which would mean 16 MHz clock or below, thus lower power, less memory bandwidth etc. TFTs don't flicker, I have played with the first one I had 5-6 years back and there was absolutely no visible benefit of increased clock frequency.

Anyone know why this minimum clock spec? Any knowledge on that? Some of the best fits I find do specify it and it is in conflict with a really major simplification I can make to the design.... So my hope is that this spec is put in order to keep some high enough frame rate to satisfy some common controller thing, not really a must. I'll try to ask the manufacturers directly, but perhaps I have a better chance to find out something via usenet.

Thanks,

Dimiter

------------------------------------------------------ Dimiter Popoff Transgalactic Instruments

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