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ADV7401.  LLC clock is ~28MHz and should be 108MHz.

Question asked by Spink Employee on May 17, 2016
Latest reply on May 19, 2016 by JeyasudhaMuthuPerumal



We’re having  trouble with the ADV7401.  The LLC clock is ~28MHz which is wrong (should be around 108MHz).


Design Info:

  • We are inputting RGB 1280x1080 60Hz Sync-on-Green.
  • We are using an external clock (28.68686MHz, +3.3V)
  • We are doing 24-bit RGB 4:4:4 Digital output


Please review the custom register settings below and advise and any potential issues.  Register settings are based on PG325 of the ADV7401 Manual


{0x0F, 0x80}, /*Reset the device*/

{0x04, 0x4D}, /*Enable sync output*/
{0x05, 0x02}, /*PRIM_MODE = 010b for GR*/
{0x06, 0x05}, /*VID_STD=0101b for 1280x1024 @ 60v*/
{0x1D, 0x47}, /*Enable 28.63636 MHz crystal*/

{0x3A, 0x21}, /*Disable ADC 3 and forces LLC range to 55-111Mhz*/

{0x13, 0x04}, /*TTL Level CLK*/
{0x3B, 0x80}, /*Enable External Bias*/

{0x3C, 0xB5},
{0x6A, 0x00}, /*DLL Phase Adjust Select Phase 0*/

{0x6B, 0x82}, /*Enable DE on the field pin and 24-bit RGB output*/

{0x73, 0x10}, /*Set auto gain*/
{0x7B, 0x1D}, /*Turn off EAV and SAV Codes. Set BLANK_RGB_SEL.*/
{0x85, 0x03}, /*Enable DS_OUT*/
{0x86, 0x0B}, /*Enable STDI Line Count Mode*/
{0xF4, 0x3F}, /*Max Drive Strength*/

{0xC3, 0x31}, /*ADC Mux*/

{0xC4, 0xC2}, /*ADC Mux + SOG enable*/
{0x0E, 0x80}, /*ADI recommended sequence*/
{0x52, 0x46}, /*ADI recommended sequence*/
{0x54, 0x00}, /*ADI recommended sequence*/
{0x0E, 0x00}  /*ADI recommended sequence*/


Additionally, we were unable to get RGB 1280X1080 with an external digital HS, VS to work with the default register settings in the manual.


Also, I noticed the user manual is dated Jan 2007.  Do any errata exist?