Dear Sir ,
Does the ADRF6755 will shut-down by itself while the temperature is so high ?
I found if the temperature is increasing and the RF output will disappear and if I used a fan to cool down the temperature and RF signal will
appear again .
No, the ADRF6755 does not shut down as the part heats up. Are you running at ambient temperature? Also what supply are you running at and what is the current consumption?
Dear TimM ,
It worked at room temperature.
I don't measeure the total current consumption .
But I try to use external power supply to connect to VREGx without REFOUT and the signal is fine.
The current consumption of VREGx is 140mA that shown at power supply .
Do you have any suggestion ?
Did you know what the CCOMPx voltage is?
I found CCOMP1 is 1.6V in the normal and if the signal was disappeared and it will up to 1.8V above.
Do you have any suggestion?
Ccomp1 is a temperature dependant voltage and would rise steadily as the temperature rises. I don't have a number for this at the moment but can you check if this rises slowly as the part heats up.
Ccomp2 = fixed voltage = 2.5x(3/7).
Ccomp3 = Vref = 2.5V.
One thing you can do to narrow down this issue is to measure the output at LOMON. I assume you are measuring at the RF output. This will narrow it down to either PLL or modulator behavior.
Also are you using an applications board or your own solution? eating effects around the ADRF6755 may influence this behavior. You should note that I have never seen this behavior before.
Yes , I just measured at RF output only .
As your suggestion , I will measure LOMON next step.
BTW, What is eating effects ?
On the other hand , I found if the signal disappeared .and Vt/Vbias /Ccomp2/ Ccomp3 and so on are correctly .
My customer said the data code is 1507 and its fail rate is above 95% and the older is noting that the Hardware is the same., so did you know any change on the different data code ?
I didn't found any PCN on website .
I meant heating effects.
No PCN, no change. The silicon has not changed since release. Can you tell me if the customer is using their own solution or my applications board.
The customer used their solution.
In addtion , not only one customer meet this isse!
As your mentioned before , the customer feedback LOMON status as below ,
When RF_OUTPUT was actived, the LOMON will be output LO spectrum.
When RF_OUTPUT wasn't actived, the LOMON will don't be output LO spectrum.
Does the customer have our applications board and if so, do they see the issue on this?
It may be that there is heat generated by other ICs in the area of the ADRF6755 that is causing this effect.
the same problem with ADRF6720 - at warming up to 40 degrees (IR thermometer measured, VPTAT = 1.3V), the output signal is lost. Оn the spectrum analyzer is like a self-excitation of the PLL - a narrow spectral components is scattered in the noise of 0.5 - 1 second. Disappears as the parasitic carrier wave and a modulated signal.
After cooling down chip, the signal is restored.
Used PLL filter nominals (and all other) from datasheet recommendadions.
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