LT1302 Datasheet, PDF (13/16 Pages) Linear Technology – Micropower High Output Current Step-Up Adjustable and Fixed 5V DC/DC Converters

LT1302/LT1302-5
APPLICATIONS INFORMATION
As an example, consider a boost converter with the
following specifications:
V_IN = 3V
V_OUT = 6V
I_OUT = 700mA
Total power loss in the LT1302, assuming R = 0.15Ω and
V_D = 0.45V, is:
( ) ( ) ^{( )( ) P}D ⁼
2
700mA 0.15Ω

² 



 6 + 0.45 ^

3
−
0.7×
6×
3
0.15 _{}
−



3
−
6 + 0.45
0.7× 6 × 0.15
3







+
0.7
6 + 0.45 − 3
27
= 223mW + 89mW = 312mW
Using the CS8 package with 100 sq. mm topside and
backside heat sinking:
∆T = (312mW)(84°C/W) = 25.9°C rise
With the N8 package:
∆T = 31.2°C
At a 70°C ambient, die temperature would be 101.2°C.
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