MIC5236 Micrel Semiconductor, MIC5236 Datasheet - Page 11

• Manufacturer Part Number: MIC5236
• Description: Low Quiescent Current Cap LDO Regulator Preliminary Information
• Manufacturer: Micrel Semiconductor

amount of copper can be determined by knowing the maxi-
mum power dissipation required. If the maximum ambient
temperature is 50 C and the power dissipation is as above,
632mW, the curve in Figure 7 shows that the required area of
copper is 25mm
The
depending upon the availability of copper ground plane to
which it is attached.
November 2000
MIC5236
JA
Figure 8. Copper Area vs. Power-MSOP
of this package is ideally 63 C/W, but it will vary
Figure 7. Copper Area vs. Power-SOP
2
Power Dissipation
.
900
800
700
600
500
400
300
200
100
900
800
700
600
500
400
300
200
100
Power Dissipation (T
0
0
0
0
T
0.25 0.50 0.75 1.00 1.25 1.50
0.25 0.50 0.75 1.00 1.25 1.50
J
POWER DISSIPATION (W)
POWER DISSIPATION (W)
= 125 C
85 C
50 C 25 C
T
A
JA
)
)
11
The same method of determining the heat sink area used for
the power-SOP-8 can be applied directly to the power-
MSOP-8. The same two curves showing power dissipation
versus copper area are reproduced for the power-MSOP-8
and they can be applied identically, see Figures 8 and 9.
Power MSOP-8 Thermal Characteristics
The power-MSOP-8 package follows the same idea as the
power-SO-8 package, using four ground leads with the die
attach paddle to create a single-piece electrical and thermal
conductor, reducing thermal resistance and increasing power
dissipation capability.
Quick Method
Determine the power dissipation requirements for the design
along with the maximum ambient temperature at which the
device will be operated. Refer to Figure 9, which shows safe
operating curves for three different ambient temperatures,
25 C, 50 C, and 85 C. From these curves, the minimum
amount of copper can be determined by knowing the maxi-
mum power dissipation required. If the maximum ambient
temperature is 50 C, and the power dissipation is 639mW,
the curve in Figure 9 shows that the required area of copper
is 110mm
Figure 9. Copper Area vs. Power-MSOP
2
,when using the power MSOP-8.
900
800
700
600
500
400
300
200
100
Power Dissipation (T
0
0
T
0.25 0.50 0.75 1.00 1.25 1.50
J
POWER DISSIPATION (W)
= 125 C
85 C
50 C 25 C
A
)
MIC5236
Micrel