STCS2_0807 Datasheet, PDF (11/16 Pages) STMicroelectronics – 2 A max constant current LED driver

STCS2
Application information
basing on this and on the thermal resistance and ambient temperature, the junction
temperature can be calculated as:
T_J = R_thJA x P_D + T_A
A typical application could be:
– Input Voltage: 12 V;
– 3 white LEDs with an typical V_F = 3.6 V;
– LEDs current: 1000 mA;
– Package: Power SO-10;
– T_A = 50 °C;
In this case the drain voltage is given by:
V_DRAIN = 12 - 3 x 3.6 = 1.2 V
end the power dissipated in the IC is the following:
P_D = (1.2 - 0.1) x 1 + 12 x 0.5 x 10^-3 = 1.1 W
With a thermal resistance junction-ambient equal to 12 °C/W the junction temperature is:
T_J = 12 x 1.1 + 50 = 63 °C.
The following pictures show the maximum power dissipation according to the ambient
temperature:
Figure 12. Maximum power dissipation vs T_A for PowerSO-10
12.00
10.00
8.00
6.00
P_DMAX = (T_JMAX-T_A)/R_thJA
R_thJA [°C/W]
12
35
4.00
2.00
0.00
25 35 45 55 65 75 85 95 105 115 125
[°C]
11/16