CMPWR130ST datasheet(6/6 Pages) CALMIRCO

6 / 6 page

3/5/2001

215 Topaz Street, Milpitas, California 95035

Tel: (408) 263-3214

Fax: (408) 263-7846

www.calmicro.com

CMPWR130

CALIFORNIA MICRO DEVICES

Typical Thermal Characteristics

The overall junction to ambient thermal resistance (

JA)

for device power dissipation (P

D) consists primarily of two

paths in series. The first path is the junction to the case

(

JC) which is defined by the package style, and the

second path is case to ambient (

CA) thermal resistance

which is dependent on board layout. The final operating

junction temperature for any set of conditions can be

estimated by the following thermal equation:

JUNC = TAMB + PD (θJC ) + PD (θCA )

= T

AMB + PD (θJA)

The CMPWR130 uses a standard SOIC package. When

this package is mounted on a double sided printed circuit

board with two square inches of copper allocated for

“heat spreading”, the resulting overall

JA is 85°C/W.

Based on maximum power dissipation of 0.51W

(1.7V x 300mA) with an ambient of 70°C the resulting

junction temperature will be:

JUNC = TAMB + PD (θJA )

= 70°C + 0.51W (85°C/W)

= 70°C + 43°C

= 113°C

Thermal characteristics were measured using a double

sided board with two square inches of copper area

connected to the GND pins for “heat spreading”.

Measurements showing performance up to junction

temperature of 125°C were performed under light load

conditions (5mA). This allows the ambient temperature to

be representative of the internal junction temperature.

Note: The use of multi-layer board construction with

power planes will further enhance the thermal perfor-

mance of the package. In the event of no copper area

being dedicated for heat spreading, a multi-layer board

construction, using only the minimum size pad layout,

will typically provide the CMPWR130 with an overall

of 100°C/W, which allows up to 0.55W to be safely

dissipated.

Figure 11. Regulator V

OUT vs TAMB (300mA Load)

Figure 12. Select and Deselect Threshold vs T

JUNC

Ambient Temperature (

˚C)

3.24

3.26

3.28

3.30

3.32

3.34

3.9

4.0

4.1

4.2

4.3

4.4

4.5

100

125

Junction Temperature (

°C)

VDESELECT

VSELECT

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