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AD9854 heating up problem and cannot communicate with the device

Question asked by arunkuttath on Apr 22, 2017
Latest reply on Apr 24, 2017 by arunkuttath

Hi

JLKeipKevin.GLouijieCDSB

I want to use AD9854ASTZ. But when i powered up it was not working actually.

So i checked the datasheet again and found one problem

   The parallel communication pins that i am not using is not properly terminated with VCC or GND.

But I reworked the board to make some necessary changes so that the unused parallel pins are terminated with VCC.

My VCC=3.3 and im using SPI Serial communication .

But when i tried this time the IC is heating up very drastically.

For the thermal design calculation its indicated that it will dissipate almost 3W energy and thermal resistance is 37.

As its junction temperature might be significantly higher ,I switched the device OFF 

 

Again i checked my schematic and found that the PLL loop filter terminated to GND instead of VCC, again my problem.

So Here im attaching the screenshot of my schematic and please tell me if any other problem persist in my design.

 

Or my board will work fine after correcting the above mentioned problems?

please do reply  someone.

Regards

ArunKuttath

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