CMPWR160SA CALMIRCO [California Micro Devices Corp], CMPWR160SA Datasheet - Page 9

• Manufacturer Part Number: CMPWR160SA
• Description: USB peripheral Power Management
• Manufacturer: CALMIRCO [California Micro Devices Corp]

©2000 California Micro Devices Corp. All rights reserved. SmartOR™ is a trademark of California Micro Devices Corporation.
12/5/2000
Typical Thermal Characteristics
Thermal dissipation of junction heat consists primarily of
two paths in series. The first path is the junction to the
case (θ
package style, and the second path is the case to
ambient (θ
board layout.
The overall junction to ambient (θ
equal to:
For a given package style and board layout, the operat-
ing junction temperature is a function of junction power
dissipation P
in the following thermal equation:
The CMPWR160SA is housed in a thermally enhanced
package where all the GND pins (5 through 8) are
integral to the leadframe (fused leadframe). When the
device is mounted on a double sided printed circuit
board with two square inches of copper allocated for
“heat spreading”, the resulting θ
Output Voltage vs. Temperature
Figure 14 shows the regulator V
the maximum rated junction temperature. A 125°C
variation in junction temperature from –25°C causes an
output voltage variation of about 50mV, reflecting
a voltage temperature coefficient of approximately
±50ppm/°C.
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JC
T
) thermal resistance which is defined by the
JUNC
θ
CA
JA
) thermal resistance, which is dependent on
JUNC
= θ
= T
= T
, and the ambient temperature, resulting
JC
AMB
AMB
+ θ
+ P
+ P
CA
JUNC
JUNC
(θ
(θ
JA
JC
)
) + P
JA
OUT
JA
is 50°C/W.
) thermal resistance is
performance up to
JUNC
(θ
CA
)
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Based on a maximum power dissipation of
1.0W (2Vx500mA) with an ambient of 70°C the resulting
junction temperature will be:
All thermal characteristics of the CMPWR160SA 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 CMPWR160SA with an overall
θ
dissipated.
JA
of 70°C/W which allows up to 780mW to be safely
Figure 14. V
T
JUNC
3.35
3.33
3.31
3.29
3.27
3.25
–25
= T
= 70°C + 1.0W (50°C/W)
= 70°C + 50°C = 120°C
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AMB
OUT
+ P
0
Temperature Variation (5mA)
JUNC
25
Temperature (˚C)
(θ
JA
)
50
75
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CMPWR160
100
125
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