402-00005-00
DAC and PLL Programming
4–20
Rev 02; February 8, 2002
PLLA4 = 0x75[1xxx] (where xxx = VCO[0:2] )
VCO bits = (calculated in step 3)
PFD = 0x3 (PFD gain always set to 15uA/2pi-rad)
PDEN = 1 (phase detector enabled)
INTFLT = 0 (external loop filter selected)
CLKSEL = 1 (select Pclk as feedback source)
MSB = 1 (reserved bit must be 1)
PLLA5 = 0x5[11xx]3 (where xx= PDA bits for PDA value in tables)
FBKSEL = 1 (always select internal feedback)
FBKPOL = 1 (always select negative edge)
ADD = 0 (use default)
SWLW = 0 (use default)
PDA = bit settings for PDA value found in tables (step 2)
PDB = 0x3 (always use PDB value = 1 if possible)
LDLG = 1 (use default)
FEN = 0 (use default)
MSB = 1 (reserved bit must be 1)
PLLA6 = 0x44[0xxx] (where xxx = LCOUNT bits for the value found in tables)
LCOUNT = bit setting for value found in tables
OMUX1 = 0 (use default)
EXTREF = 1 (external reference Input operation)
8.
Calculate Window Generator Horizontal settings as follows:
HACTIVE = [total # of pixels from hsync to end of the active region] – 2
= ( Hsync + Back Porch – Crop-End) – 2
HOFF = [Total # of pixels from Hsync to the start of active video]
= (Hsync + Back Porch + Crop-start)
Use the following formulas to determine the number of pixels in each region of the HACTIVE/HOFF formulas:
Active = Active time / Pclk (in us)
Hsync = HSync Time / Pclk (in us)
Back Porch = Back Porch Time / Pclk (in us)
Crop-End = Number of pixels to Crop from the end of active video region
Crop-Start = Number of pixel to Crop from start of active video region
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