Data Sheet

8 Thermal characteristics
The thermal characteristics of the STM32WB5MMG are defined below and the constant values are given in
Table 4 where:
• ϴ
JA,
is the junction-to-ambient thermal resistance (EIA/JESD51-2 and EIA/JESD51-6).
ϴ
JA
represents the resistance to the heat flows from the chip to ambient air. It is an indicator of package
heat dissipation capability. Lower ϴ
JA,
means better overall thermal performance and is calculated as
follows:
ϴ
JA,
= (T
J
- T
A
) / P
H,
where:
– T
J
= junction temperature
– T
A
= ambient temperature
– P
H
= power dissipation.
• Ψ
JT
is the junction-to-top-center thermal characterization parameter (EIA/JESD51-2 and EIA/JESD51-6).
Ψ
JT
is used for estimating the junction temperature by measuring T
T
in an actual environment and is
calculated as follows:
Ψ
JT
= (T
J
- T
T
) / P
H
where T
T
= temperature at the top-center of the package.
• ϴ
JC
is the junction-to-case thermal resistance.
ϴ
JC
represents the resistance to the heat flows from the chip to package top case. ϴ
JC
is important when
external heat sink is attached on package top and is calculated as follows:
ϴ
JC
= (T
J
– T
C
) / P
H
where T
C
= case temperature attached with a cold plate.
• ϴ
JB
is the junction-to-board thermal resistance (EIA/JESD51-8).
ϴ
JB
represents the resistance to the heat flows from the chip to PCB. ϴ
JB
is used in compact thermal
models for system-level thermal simulation and is calculated as follows:
ϴ
JB
= (T
J
– T
B
) / P
H
where T
B
= board temperature with ring cold plate fixture applied.
Table 4. STM32WB5MMG thermal characteristics
Symbol
T
J
(°C) T
T
(°C) Ψ
JT
(°C/W) ϴ
JA
(°C/W) ϴ
JB
(°C/W) ϴ
JC
(°C/W)
Value 97.36 96.98 0.38 37.36 24.58 16.21
STM32WB5MMG
Thermal characteristics
DS13252 - Rev 3
page 24/41