NCV4276B

http://onsemi.com

9

Thermal Model

A discussion of thermal modeling is in the ON Semiconductor web site: http://www.onsemi.com/pub/collateral/BR1487−D.PDF.

Table 1. DPAK 5−Lead Thermal RC Network Models

Drain Copper Area (1 oz thick)

(SPICE Deck Format)

Cauer Network

Foster Network

Units

Tau

Tau

Units

C_C1

Junction

GND

1.00E−06

1.00E−06

W−s/C

1.36E−08

1.361E−08

sec

C_C2

node1

GND

1.00E−05

1.00E−05

W−s/C

7.41E−07

7.411E−07

sec

C_C3

node2

GND

6.00E−05

6.00E−05

W−s/C

1.04E−05

1.029E−05

sec

C_C4

node3

GND

1.00E−04

1.00E−04

W−s/C

3.91E−05

3.737E−05

sec

C_C5

node4

GND

4.36E−04

3.64E−04

W−s/C

1.80E−03

1.376E−03

sec

C_C6

node5

GND

6.77E−02

1.92E−02

W−s/C

3.77E−01

2.851E−02

sec

C_C7

node6

GND

1.51E−01

1.27E−01

W−s/C

3.79E+00

9.475E−01

sec

C_C8

node7

GND

4.80E−01

1.018

W−s/C

2.65E+01

1.173E+01

sec

C_C9

node8

GND

3.740

2.955

W−s/C

8.71E+01

8.59E+01

sec

C_C10

node9

GND

10.322

0.438

W−s/C

sec

R’s

R’s

R_R1

Junction

node1

0.015

0.015

C/W

0.0123

0.0123

C/W

R_R2

node1

node2

0.08

0.08

C/W

0.0585

0.0585

C/W

R_R3

node2

node3

0.4

0.4

C/W

0.0304

0.0287

C/W

R_R4

node3

node4

0.2

0.2

C/W

0.3997

0.3772

C/W

R_R5

node4

node5

2.97519

2.6171

C/W

3.115

2.68

C/W

R_R6

node5

node6

8.2971

1.6778

C/W

3.571

1.38

C/W

R_R7

node6

node7

25.9805

7.4246

C/W

12.851

5.92

C/W

R_R8

node7

node8

46.5192

14.9320

C/W

35.471

7.39

C/W

R_R9

node8

node9

17.7808

19.2560

C/W

46.741

28.94

C/W

R_R10

node9

GND

0.1

0.1758

C/W

C/W

NOTE: Bold face items represent the package without the external thermal system.

Junction

Time constants are not simple RC products. Amplitudes

of mathematical solution are not the resistance values.

Ambient

(thermal ground)

Figure 13. Grounded Capacitor Thermal Network (“Cauer” Ladder)

Junction

Each rung is exactly characterized by its RC−product

time constant; amplitudes are the resistances.

Ambient

(thermal ground)

Figure 14. Non−Grounded Capacitor Thermal Ladder (“Foster” Ladder)