Ap1184, Functional descriptions – Diodes AP1184 User Manual

Page 7

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AP1184

4A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE OR

FIXED-MODE REGULATOR

AP1184 Rev. 5

7 of 12

SEPTEMBER 2008

www.diodes.com

©

Diodes Incorporated

Functional Descriptions

(Continued)


Assuming, the following conditions:

V

out

= 2.5V

V

in

= 3.3V

V

ctrl

= 5V

I

out

= 2A DC Avg.

Calculate the maximum power dissipation using the following equation:

P

d

= I

out

* ( V

in

- V

out

) + ( I

out

/60) * ( V

ctrl

- V

out

)

P

d

= 2 * (3.3-2.5) + (2/60) * (5-2.5) = 1.68W

Using table below select the proper package and the amount of copper board needed.

Package

Copper Area

θ

JA

(

o

C/W)

Max Pd (T

A

= 25

o

C)

Max Pd (T

A

= 45

o

C)

TO263-5L Pad

Size-1.4”X1.4”

25-45

2.4W-4.4W

2.0W-3.6W

Notes: 6. Above table is based on the maximum junction temperature of 135

o

C.

As shown in the above table, any of the two packages will do the job.































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