CM3003
Performance Information (cont’d)
CM3003 Typical Thermal Characteristics
The overall junction to ambient thermal resistance
(θJA) for device power dissipation (PD) consists prima-
rily of two paths in series. The first path is the junction
to the case (θJC) which is defined by the package style,
Internal Reference Voltage over Temperature
1.22
1.21
1.20
1.19
1.18
1.17
and the second path is case to ambient (θCA) thermal
resistance which is dependent on board layout. The
final operating junction temperature for any set of con-
ditions can be estimated by the following thermal equa-
tion:
T
= T
+ P (θJC) + P (θCA
)
JUNC
AMB
D
D
= T
+ P (θJA)
AMB
D
0
25
50
75 100 125 150
TEMPERATURE [oC]
The CM3003 uses a thermally enhanced package
where all the GND pins (5 through 8) are integral to the
leadframe. When this package is mounted on a double
sided printed circuit board with two square inches of
copper allocated for "heat spreading", the resulting θJA
Output Voltage (2.5V) over Temperature
2.55
2.54
2.53
2.52
2.51
2.50
2.49
2.48
2.47
2.46
2.45
is about 50°C/W.
Based on a typical operating power dissipation of 1.0W
(3.0V-2.5Vx 2.0A) with an ambient of 70°C, the result-
ing junction temperature will be:
T
= T
+ P (θJA)
JUNC
AMB
D
= 70°C + 1.0W X (50°C/W)
= 70°C + 50°C = 120°C
5mA Load
0
25
50
75 100 125 150
Thermal characteristics were measured using a double
sided board with two square inches of copper area
connected to the GND pin for "heat spreading".
TEMPERATURE [ oC]
Ground Current over Temperature
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 tempera-
ture.
350
340
330
320
310
300
Note: The use of multi-layer board construction with
separate ground and power planes will further enhance
the overall thermal performance. 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 provide the CM3003 with an overall
θJA of 70°C/W which allows up to 800mW to be safely
0
25
50 75 100 125 150
TEMPERATURE [oC]
dissipated for the maximum junction temperature.
© 2004 California Micro Devices Corp. All rights reserved.
10
430 N. McCarthy Blvd., Milpitas, CA 95035-5112
L Tel: 408.263.3214 L Fax: 408.263.7846 L www.calmicro.com 01/15/04
CALMIRCO [ CALIFORNIA MICRO DEVICES CORP ]
