NCV7361A ON Semiconductor, NCV7361A Datasheet - Page 20

• Manufacturer Part Number: NCV7361A
• Description: Voltage Regulator
• Manufacturer: ON Semiconductor

Table 1. SO−8 Thermal RC Network Models*
*Bold face items in the tables above represent the package without the external thermal system.
significance and may be divided between nodes to separate
thermal behavior due to one portion of the network from
another. The Foster networks, though when sorted by time
constant (as above) bear a rough correlation with the Cauer
networks, are really only convenient mathematical models.
Cauer networks can be easily implemented using circuit
The
Junction
C_C10
R_R10
Junction
C_C1
C_C2
C_C3
C_C4
C_C5
C_C6
C_C7
C_C8
C_C9
R_R1
R_R2
R_R3
R_R4
R_R5
R_R6
R_R7
R_R8
R_R9
Copper Area (1 oz thick)
Cauer
(SPICE Deck Format)
Each rung is exactly characterized by its RC−product time constant; Am-
plitudes are the resistances
Time constants are not simple RC products.
Amplitudes of mathematical solution are not the resistance values.
Junction
Junction
node1
node2
node3
node4
node5
node6
node7
node1
node2
node3
node4
node5
node6
node7
node8
node9
node8
node9
C
networks
1
R
C
R
1
1
1
Figure 30. Non−Grounded Capacitor Thermal Ladder (“Foster” Ladder)
Figure 29. Grounded Capacitor Thermal Network (“Cauer” Ladder)
node1
node2
node3
node4
node5
node6
node7
node8
generally
node9
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
C
2
R
C
R
2
2
2
have
1.08E−05
4.10E−05
1.13E−04
4.42E−04
1.74E−03
1.39E−03
2.08E−02
1.08E−02
1.14E−01
8.11E−01
54 mm
54 mm
18.065
27.965
80.896
49.468
0.119
0.286
0.857
1.181
1.241
2.574
Cauer Network
2
2
physical
C
http://onsemi.com
3
NCV7361A
R
C
R
3.00E+00
714 mm
714 mm
1.08E−05
4.10E−05
1.13E−04
4.40E−04
1.71E−03
1.34E−03
1.78E−02
9.75E−03
1.84E−01
3
3
3
21.708
26.035
49.821
15.252
0.286
0.859
1.189
1.276
2.690
0.119
20
2
2
simulating tools, whereas Foster networks may be more
easily implemented using mathematical tools (for instance,
in a spreadsheet program), according to the following
formula:
W−s/C
W−s/C
W−s/C
W−s/C
W−s/C
W−s/C
W−s/C
W−s/C
W−s/C
W−s/C
Units
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C/W
R(t) +
1.00E−06
1.00E−05
1.00E−04
5.00E−04
1.00E−03
1.00E−02
1.00E−01
1.00E+00
1.00E+01
5.00E+01
54 mm
26.801
63.710
86.119
0.070
0.152
0.481
0.690
0.584
3.223
0.823
Tau
i + 1
R’s
S
Foster Network
n
2
R i 1−e
1.00E+00
1.00E+01
5.00E+01
714 mm
1.00E−06
1.00E−05
1.00E−04
5.00E−04
1.00E−03
1.00E−02
1.00E−01
(thermal ground)
35.166
52.538
25.510
−t tau i
0.070
0.152
0.481
0.690
0.584
3.223
0.823
Tau
R’s
(thermal ground)
C
Ambient
n
Ambient
2
R
C
R
n
n
n
Units
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C/W
C/W
sec
sec
sec
sec
sec
sec
sec
sec
sec
sec