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ADV7181C - crystal will not oscillate

Question asked by Dan2011 on Apr 28, 2012
Latest reply on Jun 9, 2012 by Dan2011

Hello,

 

I have an issue with an ADV7181C where the crystal will not ocsillate. The conditions are listed below:

 

IC is powered (1.8V and 3.3V)

Reset pin is high

Powerdown pin is high

INT pin is not connected

The script below has been loaded via I2C. Locations 05,06 and 1D have been read back to confirm that they contain the correct values.

 

:625i/50Hz YPrPb In 8Bit 422 EAV/SAV out Encoder:

42 05 00 ; Prim_Mode =000b for SD-M

42 06 0B ; VID_STD=1010b for SD 4x1 525i

42 1D 47 ; Enable 28MHz Crystal

42 3A 11 ; Set Latch Clock 01b, Power Down ADC3

42 3B 81 ; Enable internal Bias

42 3C 52 ; PLL_QPUMP to 010b

42 67 13 ; DPP Filters

42 6B C3 ; Select 422 8 bit YPrPb out from CP

42 7B 06 ; clears the bits CP_DUP_AV and AV_Blank_EN

42 85 19 ; Turn off SSPD and force SOY. For Eval Board.

42 86 1B ; Enable stdi_line_count_mode

42 8A B0 ; Manual VCO_RANGE=01

42 8F 77 ; FR_LL to 1820 & Enable 28.63MHz LLC

42 90 1C ; FR_LL to 1820

42 BF 06 ; Blue Screen Free Run Colour

42 C0 40 ; default color

42 C1 F0 ; default color

42 C2 80 ; Default color

42 C5 01 ; CP_CLAMP_AVG_FACTOR[1-0] = 00b

42 C9 0C ; Enable DDR Mode

42 F3 07 ; Enable Anti Alias Filters on ADC 0,1,2

42 0E 80 ; ADI Recommended Setting

42 52 46 ; ADI Recommended Setting

42 54 00 ; ADI Recommended Setting

42 F6 3B ; ADI Recommended Setting

42 0E 00 ; ADI Recommended Setting

 

XTAL and XTAL1 have been measured with an oscilloscope and both seem to have just under 1V DC on them.

The crystal circuit itself is set up as per the manual (47pF caps and 1M resistor)

Trace lengths from the crystal to the pads are approx 10mm, run parallel to one another and are spaced approx 1mm apart.

 

Thanks in advance.

Dan

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