We are planning to use the Verdin Industrial Heatsink with the Verdin iMX8M Plus QuadLite 1GB IT module in our design. To help our thermal analysis, I would like to request the following information:
Under normal ambient conditions (approx. 25°C), with natural convection and a power dissipation of 6W:
What would be the expected junction temperature of the i.MX8 processor?
What would be the estimated maximum temperature of the heatsink?
Your support in providing this thermal data would be greatly appreciated to ensure proper thermal management in our application.
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Hello,
Thank you for your detailed question regarding the thermal analysis of the Verdin iMX8M Plus QuadLite 1GB IT module in conjunction with the Verdin Industrial Heatsink.
From the available documentation:
The Verdin iMX8M Plus QuadLite 1GB IT has a thermal resistance (Junction-to-Ambient, θJA) of 20.44°C/W (1).
The maximum junction temperature for the SoC is 105°C (1).
The module incorporates DVFS (Dynamic Voltage and Frequency Scaling) and Thermal Throttling to help manage the device’s temperature.
To estimate the junction temperature (Tj) of the i.MX8 processor in your scenario:
This calculation assumes the base module (without a heatsink).
The Verdin Industrial Heatsink will reduce the effective thermal resistance, so the actual junction temperature will be lower.
The precise improvement depends on the heatsink’s thermal resistance and system integration, for which exact figures aren’t available without specific system-level testing.
For the maximum heatsink temperature:
Generally, the heatsink will be cooler than the SoC junction but warmer than ambient.
If the heatsink’s thermal resistance (θSA, sink-to-ambient) is known, you could estimate:
Heatsink temperature = Ta + (θSA × Power Dissipation through Heatsink)
(Without θSA, only lab measurements or manufacturer specs can provide an exact number.)
Summary:
The calculated junction temperature (147.64°C) is only an upper-bound estimation without a heatsink.
Using the Verdin Industrial Heatsink will significantly improve this value, but detailed heatsink performance data or measurements are required for a precise answer.
Keep in mind the SoC’s built-in DVFS and thermal throttling features will also help maintain safe operating temperatures.
Thank you for the reply. Please have a look at the enclosed screen shot from 116795-verdin_imx8mp_datasheet.pdf. Thermal resistance value for i.MX8M Plus shown here seems contradictory, can you please explain?
Junction-to-Top of Package Thermal Characterization Parameter (ΨJT)
Definition:
ΨJT represents the thermal characterization parameter between the semiconductor junction (the hottest part of the die) and the top surface of the package.
It is not a true thermal resistance but rather an empirical value derived from measurements.
It helps estimate the junction temperature when the package top temperature is known.
Useful when a heat sink is not used, and cooling is primarily through the top surface (e.g., natural convection).
. Junction-to-Case Thermal Resistance (RθJC)
Definition:
RθJC is the true thermal resistance between the junction and the case (package exterior).
It assumes all heat flows through the case (typically the bottom for many packages).
Thermal conductivity (CPU to metal heatsink), R(cpu-heatsink) = 1/1.55 C/W = 0.645 C/W
Thermal conductivity (metal heatsink to air), R(heatsink-air) = 1/9.1 C/W = 0.110 C/W
Junction-to-Case Thermal Resistance, R (junction -case) = 0.24 C/W
Power dissipation P= 6 W
Ambient temp T(ambient) = 25 C
Assuming all 6 Watt will be transferred to the heatsink
T(heartsink) - T(ambient) = P * R(heatsink-air)
T(heartsink) = P * R(heatsink-air) + T(ambient)
T(heartsink) = 6 * 0.11 +25 = 25.66 C
R (junction - heatsink) = R (junction -case) + R(cpu-heatsink) = 0.24 + 0.645 = 0.885 C/W
T (junction) - T(heatsink) = P * R(junction - heatsink) T (junction) = P * R(junction - heatsink) + T(heatsink) = 25.66 +6 * 0.885 = 30.97C
However, I still have some confusion regarding the data. The information provided in the Verdin industrial heat sink datasheet refers to thermal resistance, whereas it seems you are interpreting it as thermal conductivity.
Additionally, the Verdin datasheet specifies a thermal resistance of 0.98°C/W. Please have a look at the attached screenshot for reference.
The actual junction temperature will be slightly lower due to some heat dissipation through the PCB. However, we strongly recommend using a fan in such cases to prevent CPU frequency throttling.
On the other hand, our tests show that the 6.07 W power consumption observed on the Verdin iMX8M Plus QuadLite 1GB occurred only on some module samples. The mean power consumption under the same load across multiple units is approximately 4.2 W.
Additionally, the SoC accounts for only part of the total module power consumption (albeit the largest share), so the actual junction temperature will be significantly lower than 90 °C in most scenarios. So fan is not mandatory here.
Thanks Alex, that seems better. From latest information we’re also expecting the power consumption below 4W only, but due to space constraints we’re planning to reduce the fin height of this same heat sink to 6mm, original is 11mm. Could you help me to predict the derating of this heat sink for reduced fin size?
It’s very difficult to obtain even roughly accurate data without simulating airflow and convection. However, as a very rough estimate, you can assume that the thermal resistance from metal to air is inversely proportional to the surface area.
To do this, calculate the surface area of the existing heatsink (A_old) and the surface area of your new heatsink (A_new). Then, estimate the new metal-to-air thermal resistance as:
R_ma_new ≈ 9.1 × (A_old / A_new)C/W
You can then use this estimated value in the previous thermal calculations.
