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VREF output of ADL5519

Question asked by ZhengNice on Jan 11, 2017
Latest reply on Jan 12, 2017 by ZhengNice

Hi jdobler,

   I want to use the ADL5519 to detect the input signal power,  and I draw the schematic based on the  EVALUATION BOARD SCHEMATIC AND ARTWORK at page 37 in the datasheet of ADL5519. 

   I have made some changes in the design, leave all PIN COMR floating and connected the paddle to ground. I did this because I have seen that the paddle is internally connected to COMR, as could be seen at page 10 in the datasheet of ADL5519

so I thought all the COMR are same and connected to the paddle, and  I can just connected the paddle to ground and all the COMR could also be connected to ground, as it can be seen in bellow.  The pin 0 PAD means the paddle of ADL5519 at the bottom, and connect to ground.

 

But when the PCB is finished, I test the output voltage of pin VREF , TEMP is zero, the COMRs are not connected each other, the out voltage of pin OUTA,OUTB is not the theory value, but the change slope (V/dB) of the power of input signal is same to the theory value.

 

So, I have some questions:

1. Are all the pin COMR same?

2. What is the meaning of paddle internally connected to COMR? 

3. Is the zero V ouput of pin VREF, pin TEMP caused by I just connect the paddle to ground and leave the pin COMR floating?

4. And is the output of pin OUTA, OUTB also caused as mentioned before?

 

Best Regards

Outcomes