Behavior at high temperature about HMC7044

For Example, 

thermal shutdown, low power consumption mode at high temperature, etc.

Is there any behavior like the above that is not written in the data sheet?

Hi,

There is no thermal shutdown mode on the device. 

Is there any SPI programming from beginning to the time you see the drop? Are you seeing any difference on the current consumption of the part? 

Kudret

Hi,

Thank you for your reply.

Is there any SPI programming from beginning to the time you see the drop?

>No. SPI programming is done only after the startup.

Are you seeing any difference on the current consumption of the part? 

>I'm sorry,  I can't measure the current consumption of the IC alone.

However, the current consumption of the entire device was measured and confirmed to be unchanged.

The temperature graph of each point in the entire device is also attached below.

(Only HMC7044 has dropped)

Best regard

KoheiT

Hi,

Thanks for the reply. As it seems pretty unusual, I have other questions. 

- Did you test one system or multiple systems? If you measured multiple systems, is it same on different systems? 

- How do you measure the case temperature, thermocouple? If so, how do yo fix it on the case? Can you try to change HMC7044 measurement equipment with another part on the system? 

Kudret

Hi

Thanks for the reply, and sorry for the late reply.

- Did you test one system or multiple systems? If you measured multiple systems, is it same on different systems? 

>I tested on two same systems and both has the same behavier.

- How do you measure the case temperature, thermocouple? If so, how do yo fix it on the case? Can you try to change HMC7044 measurement equipment with another part on the system? 

>I attached the thermocouple directly to the case using Kapton tape.
It was the same even if I changed it with another place.

KoheiT

Hi,

I don't see any reason to have such behavior. ~30min is a long time and does not correlate with anything that I can think of. 

Is it possible that Kapton tape is loosen and loose the contact? Did you re-run the same board after power-off? Is there any difference between multiple runs? 

Kudret

Hi,

Thank you for your reply.

I also thought that time was too long.

Is it possible that Kapton tape is loosen and loose the contact?
>I don't think it is. The Kapton tape did not come off after the test.

Did you re-run the same board after power-off?
Is there any difference between multiple runs? 
>I tested it several times and the results were the same.

When tested at low temperature (-10℃), there was no drop and a smooth curve was drawn.

 KoheiT

Thanks for the clarification. 

Above plot states improved heat dissipation version. What kind of heat dissipation/cooling solution you are using? Can it be related with this behavior?

Kudret

Thanks for your reply.

In previous tests, the outside air temperature was adjusted in a constant temperature bath.
(ESPEC Corp. PWL-3KP)

What we now know is that the temperature drop occurs only when the surface temperature of the HMC7044 reaches around 60 ° C.

Also, when an air cooling fan was added (when the outside temperature was 25 ° C), the surface temperature did not exceed 60 ° C, and the curve was as smooth as when it was -10 ° C.

Eventually we'll be adding more cooling fans, but I'd like to know the cause of this drop.

KoheiT

Hi,

This seems to be related with a system level cooling parameter, bot sure what it is. HMC7044 does not have any feature that might cause this. If current consumption is constant, I cannot think of any reason that might cause case temperature decrease other than a fan starting to blow air or decrease in the ambient temperature.

Kudret