PKC-136
3/5
1.E-01
1.E+00
1.E+01
1.E+02
1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01
tp(ms)
Tj initial=25°C
Pp(kW)
Fig. 1: Peak pulse power versus exponential pulse
duration.
0
10
20
30
40
50
60
70
80
90
100
110
0 25 50 75 100 125 150 175
Tj(°C)
%
Fig. 2: Relative variation of peak pulse power
versus initial junction temperature.
Symbol Parameter Value Unit
R
th(j-l)
Junction to leads L = 10mm
40 °C/W
R
th(j-a)
Junction to ambiant condition see note 1
105 °C/W
Note 1: Device mounted on a epoxy FR4 board of 35µm thickness
Lead Length: 10mm
Pad diameter: 4mm
Track width: 1mm
Track length: 25mm
The Rth
(j-a)
can be reduced by replacing the Cu track by plan:
S(Cu) = 1.5cm
2
/lead R
th(j-a)
= 65°C/W
S(Cu) = 3.5cm
2
/lead R
th(j-a)
= 60°C/W
THERMAL RESISTANCES
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 25 50 75 100 125 150
Tamb(°C)
Tamb=Tleads
Printed circuit board
P(W)
Fig. 3: Average power dissipation versus ambient
temperature.
1.0
10.0
100.0
1000.0
1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03
Zth(j-a) (°C/W)
Free air
tp(s)
Fig. 4: Variation of thermal impedance junction to
ambient versus pulse duration (printed circuit
board epoxy FR4)
