AN609 View Datasheet(PDF) - Vishay Semiconductors
Part Name
Description
Manufacturer
AN609 Datasheet PDF : 9 Pages
| |||
AN609
Vishay Siliconix
1.0KW
(A) j-c tank.dat (active)
Temperature: 27.0
160c
0.8W
0.6W
0.4W
120c
80c
40c
0.2W
0W
0s
1
40us
80us
120us
I(I2) 2 V(R1:1) Time
160us
Figure 10: j-c Tank Simulations
Red: Junction temperature
Blue: Power profile
>>
0c
200us
The simulation result shows that the junction tempera-
ture rises to 150 °C with just one power pulse.
Next, create a new design folder Filter j-c and add a
schematic page as shown in Figure 11, Filter Configura-
tion.
Junction Temperature
R1
R2
R3
164.8787n 888.7177m 1.2671
C1
C2
I2 166.0609u 357.5156u
C:\Si7390DP_RC\900w100uS.txt
Power Profile
I
C3
4.6473m
R4
1.0331
C4 25Vdc V1
304.1798u
Ambient
0
Figure 11: j-c Filter Configuration
1.0KW
0.8W
0.6W
0.4W
x
0.2W
(A) Filter j-c.dat (active)
Temperature: 27.0
180c
x
x
x
150c
x
100c
x
50c
We can observe that the junction temperature value
obtained by either configuration is within 5 to 7 degrees
Centigrade. These results are acceptable for all practical
purposes.
SUMMARY
R-C thermal model parameters are available for Vishay
power MOSFETs under the product information menu.
These models can be used on the P-Spice platform to
estimate the junction temperature of the MOSFET that is
dissipating transient power. The j-a model parameters
are employed for repetitive, high peak power and longer
duty cycle pulses. All these cases result in residual junc-
tion temperatures at the end of each period. On the
other hand, the j-c model parameters are employed for
single, very high power transients. However, in these
cases the junction temperature returns to ambient
before the subsequent power pulse is applied. The esti-
mation of junction temperature falls within a practically
acceptable range of +/- 5 °C to 7 °C. This approach
offers a quick, simple, and very useful alternative to
high-end complex thermal modeling tools.
REFERENCES:
[1] "A Simplified Method of Generating Thermal Models
for Power MOSFETs, "Kandarp I. Pandya and Whar-
ton McDaniel, March 2002 IEEE SEMI-THERM Pro-
ceedings.
[2] "Thermal Modeling for Power MOSFETs in DC/Dc
Applications, "Yalcin Bulut and Kandarp Pandya,
May 2004 Euro-Sime Proceedings.
[3] "Thermal Analysis of Power MOSFETs Using
Rebeca-3D Thermal Modeling Software (From Epsi-
lon Ingenierie) versus Physical Measurements and
Possible Extractions, "Kandarp Pandya and Serge
Jaunay, April 2005 Euro-Sime Proceedings.
[4] "Rigorous Model and Network for Transient Thermal
Problems, "Y.C. Gerstenmaier and G. Wachutka, 7th
Therminic Workshop, September 2001.
0W
0s
40us x 80us
120us
1 I(I2) 2 V(R1:1) Time
>>
0c
160us 200us
Figure 12: j-c Filter Simulation Results
www.vishay.com
6
Document Number 73554
07-Oct-05
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