Kontron SMARC-sAT30 - Manual (Page 77)

User’s Guide
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The table below describes the function and assembly hardware required by each of the heatspreader holes.
Hole Heatspreader SMARC sAT30 Evaluation Carrier
A
3mm standoffs
Clearance for M2.5
Clearance holes M2.5 Threaded Standoffs
B Clearance for M2.5
3mm captive standoff
M2.5 thread
N/A
C M3 thread N/A N/A
6.3 Thermal Parameters
The T30 SoC thermal parameters are shown in the table below:
Description Detail
Junction Temperature(Tj) max 90 0 C
Thermal Resistance, CPU Junction to ambient (
θ
JA
) 11.6 0 C/W
Thermal Resistance, CPU Junction to case (
θ
JC
) 1.18 0 C/W
Thermal Resistance, CPU case to heat spreader far surface (
θcs)
Less than 1 0 C/W
A heat spreader is available now from Kontron for the sAT30 Module. A passive heat sink solution is pending.
6.4 Operation without a Heat Spreader / Heat Sink
The SMARC sAT30 Module is sometimes used in a room temperature environment without any heat sink at all. While it is
easy and convenient, it is not generally recommended, as it can put the Tegra CPU die at or above the 90 0 C limit,
depending on what you are running and how system performance parameters (CPU speed, number of cores active,
etc.).
At the Linux desktop, without any heat sinking at all, assuming a typical Module power consumption of 1.6W and an
ambient room temperature of 23
0
C, the CPU die would be at about 42
0
C (1.6W * 11.6
0
C/W + 23
0
C). The temperature
may actually be a bit less, as not all of the assumed 1.6W is going to the Tegra.
Running an MPEG4 decode, with all Module features (USB, PCIe, GBE, SATA) enabled has a typical power consumption
of 5.5W. This yields a calculated CPU die temperature of 87
0
C - pretty close to the Tegra limit.
The stress test, at 7W, puts the Tegra well over the die temperature limit, if there is no heat sinking.