Datasheet

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STM8S105x4/6 Thermal characteristics
107
12.2 Selecting the product temperature range
When ordering the microcontroller, the temperature range is specified in the order code (see
Section 13: Ordering information).
The following example shows how to calculate the temperature range needed for a given
application.
Assuming the following application conditions:
Maximum ambient temperature T
Amax
= 82°C (measured according to JESD51-2),
I
DDmax
= 15 mA, V
DD
= 5.5 V
Maximum 8 standard I/Os used at the same time in output at low level with
I
OL
= 10 mA, V
OL
= 2 V
Maximum 4 high sink I/Os used at the same time in output at low level with
I
OL
= 20 mA, V
OL
= 1.5 V
Maximum 2 true open drain I/Os used at the same time in output at low level with
I
OL
= 20 mA, V
OL
= 2 V
P
INTmax
= 15 mA x 5.5 V= 82.5 mW
P
IOmax
= (10 mA x 2 V x 8) + (20 mA x 2 V x 2) + (20 mA x 1.5 V x 4) = 360 mW
This gives: P
INTmax
= 82.5 mW and P
IOmax
= 360 mW:
P
Dmax
= 82.5 mW + 360 mW
Thus: P
Dmax
= 443 mW.
Using the values obtained in Table 56: Thermal characteristics T
Jmax
is calculated as
follows:
For LQFP32 60°C/W
T
Jmax
= 82°C + (60°C/W x 443 mW) = 82°C + 27°C = 109 °C
This is within the range of the suffix 6 version parts (-40 < T
J
< 131°C).
Parts must be ordered at least with the temperature range suffix 3.