NCV8503 ON Semiconductor, NCV8503 Datasheet - Page 11

• Manufacturer Part Number: NCV8503
• Description: 2.5v, 3.3v, 5.0v, Adjustable/400ma Ldo W/ Reset, Delay, Adjustable Reset, Enable And Early Warning
• Manufacturer: ON Semiconductor

regulator (Figure 23) is:
P D(max) + [V IN(max) * V OUT(min) ] I OUT(max)
where:
permissible value of R
The maximum power dissipation for a single output
V
V
I
application, and
I
I
Once the value of P
Figure 22. 16 Lead SOW (Exposed Pad), qJA as a
OUT(max)
Q
OUT(max)
Thickness), Board Material = 0.0625, G-10/R-4
IN(max)
OUT(min)
100
CALCULATING POWER DISSIPATION IN A
90
80
70
60
50
40
is the quiescent current the regulator consumes at
SINGLE OUTPUT LINEAR REGULATOR
Function of the Pad Copper Area (2 oz. Cu
0
is the maximum input voltage,
.
) V IN(max) I Q
is the minimum output voltage,
is the maximum output current for the
R qJA + 150°C *
200
qJA
Copper Area (mm
D(max)
can be calculated:
400
P D
is known, the maximum
T A
2
)
600
NCV8503 Series
http://onsemi.com
800
(1)
(2)
11
package section of the data sheet. Those packages with
R
the die temperature below 150°C.
dissipate the heat generated by the IC, and an external
heatsink will be required.
package to improve the flow of heat away from the IC and
into the surrounding air.
outside environment will have a thermal resistance. Like
series electrical resistances, these resistances are summed to
determine the value of R
where:
R
functions of the package type, heatsink and the interface
between them. These values appear in heat sink data sheets
of heat sink manufacturers.
qJA
qJA
The value of R
In some cases, none of the packages will be sufficient to
A heat sink effectively increases the surface area of the
Each material in the heat flow path between the IC and the
R
R
R
R
qJC
qCS
qSA
qJC
's less than the calculated value in equation 2 will keep
, it too is a function of package type. R
V
Figure 23. Single Output Regulator with Key
IN
= the junction-to-case thermal resistance,
appears in the package section of the data sheet. Like
= the case-to-heatsink thermal resistance, and
= the heatsink-to-ambient thermal resistance.
Performance Parameters Labeled
R qJA + R qJC ) R qCS ) R qSA
I
IN
qJA
can then be compared with those in the
HEAT SINKS
REGULATOR®
qJA
}
SMART
Control
Features
:
I
Q
qCS
I
OUT
and R
qSA
V
OUT
are
(3)