STM8S105C4 Datasheet, PDF (107/121 Pages) STMicroelectronics – Extended instruction set

STM8S105x4/6
Thermal characteristics
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.
DocID14771 Rev 15
107/121
107