Datasheet

STM32F051x Package characteristics
Doc ID 022265 Rev 3 101/105
7.2.1 Reference document
JESD51-2 Integrated Circuits Thermal Test Method Environment Conditions - Natural
Convection (Still Air). Available from www.jedec.org
7.2.2 Selecting the product temperature range
When ordering the microcontroller, the temperature range is specified in the ordering
information scheme shown in Section 8: Part numbering.
Each temperature range suffix corresponds to a specific guaranteed ambient temperature at
maximum dissipation and, to a specific maximum junction temperature.
As applications do not commonly use the STM32F05xx at maximum dissipation, it is useful
to calculate the exact power consumption and junction temperature to determine which
temperature range will be best suited to the application.
The following examples show how to calculate the temperature range needed for a given
application.
Example 1: High-performance application
Assuming the following application conditions:
Maximum ambient temperature T
Amax
= 82 °C (measured according to JESD51-2),
I
DDmax
= 50 mA, V
DD
= 3.5 V, maximum 20 I/Os used at the same time in output at low
level with I
OL
= 8 mA, V
OL
= 0.4 V and maximum 8 I/Os used at the same time in output
at low level with I
OL
= 20 mA, V
OL
= 1.3 V
P
INTmax
= 50 mA × 3.5 V= 175 mW
P
IOmax
= 20 × 8 mA × 0.4 V + 8 × 20 mA × 1.3 V = 272 mW
This gives: P
INTmax
= 175 mW and P
IOmax
= 272 mW:
P
Dmax
= 175 + 272 = 447 mW
Using the values obtained in Table 7 2 T
Jmax
is calculated as follows:
– For LQFP64, 45 °C/W
T
Jmax
= 82 °C + (45 °C/W × 447 mW) = 82 °C + 20.115 °C = 102.115 °C
This is within the range of the suffix 6 version parts (–40 < T
J
< 105 °C) see Ta bl e 2 0 :
General operating conditions.
In this case, parts must be ordered at least with the temperature range suffix 6 (see
Section 8: Part numbering).
Table 72. Package thermal characteristics
Symbol Parameter Value Unit
Θ
JA
Thermal resistance junction-ambient
LQFP64 - 10 × 10 mm / 0.5 mm pitch
45
°C/W
Thermal resistance junction-ambient
LQFP48 - 7 × 7 mm
55
Thermal resistance junction-ambient
LQFP32 - 7 × 7 mm
56
Thermal resistance junction-ambient
UFQFPN32 - 5 × 5 mm
38