Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 5

Copyright

© 2000

Rev. 1.1a, 2006-01-19

LX8221

Dual 150mA CMOS Low Dropout Regulator

TM

®

APPLICATIONS

be calculated using the following equation:

(

)

)

(

)

(

)

(

MAX

OUT

MIN

OUT

MAX

IN

D

I

V

V

P

×

−

=

(Note: power dissipation resulting from quiescent current

is negligible)

For the MSOP package, thermal resistance,

when mounted on a FR4 copper clad PCB. Junction

temperature of the integrated circuit can be calculated

using:

RISE

A

J

T

T

T

+

=

Where:

()

JA

D

RISE

P

T

Θ

×

=

Example: Given the following conditions:

calculate the total power dissipation and junction

temperature:

Total Power Dissipation:

(

)

W

15

.

0

A

1

.

0

V

7

.

2

V

2

.

4

P

D

=

×

−

=

Junction Temperature:

(

)

C

W

C

W

C

T

o

o

o

J

91

/

206

15

.

0

60

=

×

+

=

Layout Consideration:

The layout must be implemented with low impedance paths

traces to avoid voltage drops and pick up noise. Adding an

area of PCB copper to the GND pin (pin 8) will reduce the

overall

substrate. This will lower the device junction temperature

improving overall output voltage accuracy. The input/output

capacitors must be placed as close as possible to each

voltage regulator output pin.