Package characteristics
STM32F103xx
6.1
Thermal characteristics
The average chip-junction temperature, T , in degrees Celsius, may be calculated using the
J
following equation:
T = T + (P x Θ )
(1)
J
A
D
JA
Where:
■
■
■
■
T is the Ambient Temperature in °C,
A
Θ
is the Package Junction-to-Ambient Thermal Resistance, in ° C/W,
JA
P is the sum of P
and P (P = P
+ P ),
INT I/O
D
INT
I/O
D
P
is the product of I and V , expressed in Watts. This is the Chip Internal Power.
DD DD
INT
P
represents the Power Dissipation on Input and Output Pins;
I/O
Most of the time for the application P < P and can be neglected. On the other hand, P
I/O
I/O
INT
may be significant if the device is configured to drive continuously external modules and/or
memories.
An approximate relationship between P and T (if P is neglected) is given by:
D
J
I/O
P = K / (T + 273 °C)
(2)
D
J
Therefore (solving equations 1 and 2):
2
K = P x (T + 273°C) + Θ x P
D
(3)
D
A
JA
where:
K is a constant for the particular part, which may be determined from equation (3) by
measuring P (at equilibrium) for a known T Using this value of K, the values of P and T
J
D
A.
D
may be obtained by solving equations (1) and (2) iteratively for any value of T .
A
Table 46. Thermal characteristics
Symbol
Parameter
Value
Unit
Thermal resistance junction-ambient
LFBGA100 - 10 x 10 mm / 0.5 mm pitch
41
Thermal resistance junction-ambient
LQFP100 - 14 x 14 mm / 0.5 mm pitch
46
45
55
Θ
°C/W
JA
Thermal Resistance Junction-Ambient
LQFP64 - 10 x 10 mm / 0.5 mm pitch
Thermal resistance junction-ambient
LQFP48 - 7 x 7 mm / 0.5 mm pitch
64/67
STMICROELECTRONICS [ ST ]
