Datasheet

Package characteristics STM32F050xx
94/97 Doc ID 023683 Rev 1
Example 1: High-performance application
Assuming the following application conditions:
Maximum ambient temperature T
Amax
= 80 °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 Tabl e 6 5 T
Jmax
is calculated as follows:
– For LQFP48, 55 °C/W
T
Jmax
= 80 °C + (55°C/W × 447 mW) = 80 °C + 24.585 °C = 104.585 °C
This is within the range of the suffix 6 version parts (–40 < T
J
< 105 °C) see Ta bl e 1 5 :
General operating conditions on page 39.
In this case, parts must be ordered at least with the temperature range suffix 6 (see
Section 8: Part numbering).
Note: With this given P
Dmax
we can find the T
Amax
allowed for a given device temperature range
(order code suffix 6 or 7).
Suffix 6: T
Amax
= T
Jmax
- (55°C/W × 447 mW) = 105-24.585 = 80.415 °C
Suffix 7: T
Amax
= T
Jmax
- (55°C/W × 447 mW) = 125-24.585 = 100.415 °C
Example 2: High-temperature application
Using the same rules, it is possible to address applications that run at high ambient
temperatures with a low dissipation, as long as junction temperature T
J
remains within the
specified range.
Assuming the following application conditions:
Maximum ambient temperature T
Amax
= 100 °C (measured according to JESD51-2),
I
DDmax
= 20 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
P
INTmax
= 20 mA × 3.5 V= 70 mW
P
IOmax
= 20 × 8 mA × 0.4 V = 64 mW
This gives: P
INTmax
= 70 mW and P
IOmax
= 64 mW:
P
Dmax
= 70 + 64 = 134 mW
Thus: P
Dmax
= 134 mW
Using the values obtained in Tabl e 6 5 T
Jmax
is calculated as follows:
– For LQFP48, 55 °C/W
T
Jmax
= 100 °C + (55 °C/W × 134 mW) = 100 °C + 7.37 °C = 107.37 °C
This is above the range of the suffix 6 version parts (–40 < T
J
< 105 °C).
In this case, parts must be ordered at least with the temperature range suffix 7 (see
Section 8: Part numbering) unless we reduce the power dissipation in order to be able to
use suffix 6 parts.