DocID025832 Rev 5
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STM32F042x4 STM32F042x6
Package information
113
7.8 Thermal
characteristics
The maximum chip junction temperature (T
J
max) must never exceed the values given in
Table 21: General operating conditions
The maximum chip-junction temperature, T
J
max, in degrees Celsius, may be calculated
using the following equation:
T
J
max = T
A
max + (P
D
max x
Θ
JA
)
Where:
•
T
A
max is the maximum ambient temperature in °C,
•
Θ
JA
is the package junction-to-ambient thermal resistance, in °C/W,
•
P
D
max is the sum of P
INT
max and P
I/O
max (P
D
max = P
INT
max + P
I/O
max),
•
P
INT
max is the product of I
DD
and V
DD
, expressed in Watts. This is the maximum chip
internal power.
P
I/O
max represents the maximum power dissipation on output pins where:
P
I/O
max
=
Σ
(V
OL
× I
OL
) +
Σ
((V
DDIOx
– V
OH
) × I
OH
),
taking into account the actual V
OL
/ I
OL
and V
OH
/ I
OH
of the I/Os at low and high level in the
application.
7.8.1 Reference
document
JESD51-2 Integrated Circuits Thermal Test Method Environment Conditions - Natural
Convection (Still Air). Available from www.jedec.org
7.8.2
Selecting the product temperature range
When ordering the microcontroller, the temperature range is specified in the ordering
information scheme shown in
Section 8: Ordering information
Table 74. Package thermal characteristics
Symbol
Parameter
Value
Unit
Θ
JA
Thermal resistance junction-ambient
LQFP48 - 7 mm x 7 mm
55
°C/W
Thermal resistance junction-ambient
UFQFPN48 - 7 mm x 7 mm
33
Thermal resistance junction-ambient
WLCSP36 2.6 mm x 2.7 mm
64
Thermal resistance junction-ambient
LQFP32 - 7 mm x 7 mm
57
Thermal resistance junction-ambient
UFQFPN32 - 5 mm x 5 mm
38
Thermal resistance junction-ambient
UFQFPN28 - 4 mm x 4 mm
118
Thermal resistance junction-ambient
TSSOP20 - 6.5 mm x 6.4 mm
76
