CM3103-01SF CALMIRCO [California Micro Devices Corp], CM3103-01SF Datasheet - Page 9

• Manufacturer Part Number: CM3103-01SF
• Description: 400mA SMARTOR REGULATOR Vaux SWITCH
• Manufacturer: CALMIRCO [California Micro Devices Corp]

01/28/04
Performance Information (cont’d)
CM3103 Typical Thermal Characteristics
The overall junction to ambient thermal resistance
(
rily of two paths in series. The first path is the junction
to the case (
and the second path is case to ambient (
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:
The CM3103 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
is about 50°C/W.
Based on a typical operating power dissipation of 0.7W
(1.75V x 0.4A) with an ambient of 70°C, the resulting
junction temperature will be:
Thermal characteristics were measured using a double-
sided board with two square inches of copper area con-
nected to the GND pin 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 tempera-
ture.
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 CM3103 with an overall
θ
dissipated for the maximum junction temperature.
© 2004 California Micro Devices Corp. All rights reserved.
θ
JA
JA
) for device power dissipation (P
of 70°C/W which allows up to 780mW to be safely
T
JUNC
T
430 N. McCarthy Blvd., Milpitas, CA 95035-5112
JUNC
θ
= T
= T
= T
JC
= 70°C + 0.7W X (50°C/W)
= 70°C + 35°C = 105°C
AMB
AMB
) which is defined by the package style,
AMB
+ P
+ P
+ P
D
D
D
(
(
θ
(
θ
θ
JA
JC
JA
)
) + P
)
D
D
(
θ
) consists prima-
CA
)
θ
CA
) thermal
L Tel: [phone]
θ
JA
4.55
4.50
4.45
4.40
4.35
4.30
4.25
4.20
3.32
3.31
3.30
3.29
3.28
0.37
0.35
0.33
0.31
0.29
0.27
0.25
L
25
20
20
Fax: [phone]
50
30
30
Temperature [
Temperature [
Temperature [
75
40
40
Vselect
Vdeselect
L
100
50
50
o
o
www.calmicro.com
C]
o
C]
C]
125
60
60
CM3103
150
70
70
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