imx6ull 工业级在80度高温测试会 power down，请问下是否正常

[michael_yang]

imx6ull MCIMX6Y2CVM05AB 工业级在80度高温测试会 power down, 芯片规格书写了Temperature
Tj -40 to 105

[riteshmpatel]

Hi @michael_yang,

I hope you are doing well.

Could you confirm if the 80 degrees is the ambient temperature or the processor's junction temperature?

Thanks & Regards,
Ritesh M Patel

[michael_yang]

Hi Team, 

80 degrees is the ambient temperature

[riteshmpatel]

Hi @michael_yang,

Thanks for the confirmation.

Since 80 degrees is the ambient temperature, please share the logs of the processor before it shut down, mentioning the junction temperature of the processor.
I expect the junction temperature to be pretty more at 80 degrees of ambient temperature.

One can print the junction temperature of the processor continuously on the console by using the below-mentioned command:
cat /sys/devices/virtual/thermal/thermal_zone0/temp

Thanks & Regards,
Ritesh M Patel 

[michael_yang]

Hi @riteshmpatel

we look at log cat /sys/devices/virtual/thermal/thermal_zone0/temp, and running at 80 degrees for 10 minutes, there is a power down, junction temperature is close to 105 degrees, is it a hardware problem?

[riteshmpatel]

Hi @michael_yang,

Apologies for the delay in response.

The junction temperature will always be greater than the ambient temperature.

To calculate Tj(Junction temperature) you need to use the equation Tj = Ta + ( RθJA * PD ).

Ta = Ambient temperature

RθJA = Junction to ambient thermal resistance (51.4 °C/W)

PD = Power dissipation (Vout * Iout)

Thanks & Regards,
Ritesh M Patel

[smithcoba]

@riteshmpatel 

The cat /sys/devices/virtual/thermal/thermal_zone0/temp is already the temperature from  junction.

Your formula is thermal resistance to estimate  junction temperature.

For example, know the  Ambient and the power, then you can calculate/estimate the junction temperature.

So far, at this moment, is to check the passive and critical settings. 

cat /sys/devices/virtual/thermal/thermal_zone0/trip_point_?_*
2000
85000
passive
2000
95000
critical