Package characteristics
STM32F042xx
DocID025832 Rev 2
7.2 Thermal
characteristics
The maximum chip junction temperature (T
J
max) must never exceed the values given in
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
JA
)
Where:
T
A
max is the maximum ambient temperature in °C,
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
=
(V
OL
× I
OL
) +
((V
DD
– 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.
7.2.1 Reference
document
JESD51-2 Integrated Circuits Thermal Test Method Environment Conditions - Natural
Convection (Still Air). Available from www.jedec.org
Table 72. Package thermal characteristics
Symbol
Parameter
Value
Unit
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 die 445
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
