Datasheet

© 2007 Microchip Technology Inc. DS22001C-page 21
MCP1827/MCP1827S
5.3.1.2 Junction Temperature Estimate
To estimate the internal junction temperature, the
calculated temperature rise is added to the ambient or
offset temperature. For this example, the worst-case
junction temperature is estimated below:
As you can see from the result, this application will be
operating within the maximum operating junction
temperature of 125°C.
5.3.1.3 Maximum Package Power
Dissipation at 60°C Ambient
Temperature
From this table you can see the difference in maximum
allowable power dissipation between the TO-220-5
package and the DDPAK-5 package.
T
J
=T
JRISE
+ T
A(MAX)
T
J
= 45.12°C + 60.0°C
T
J
= 105.12°C
TO-220-5 (29.3° C/W Rθ
JA
):
P
D(MAX)
= (125°C – 60°C) / 29.3° C/W
P
D(MAX)
= 2.218W
DDPAK-5 (31.2°C/Watt Rθ
JA
):
P
D(MAX)
= (125°C – 60°C)/ 31.2° C/W
P
D(MAX)
= 2.083W