CMPWR101(2010) Ver la hoja de datos (PDF) - ON Semiconductor
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CMPWR101 Datasheet PDF : 12 Pages
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CMPWR101
Performance Information (cont’d)
CMPWR101 Typical Thermal Characteristics
The overall junction to ambient thermal resistance (θJA) for device power dissipation (PD) consists primarily
of two paths in series. The first path is the junction to the case (θJC) which is defined by the package style,
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 conditions can be estimated by the following thermal
equation:
TJUNC
= TAMB + PD (θJC) + PD (θCA)
θ = TAMB + PD ( )JA
The CMPWR101 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 θJA is
85°C/W.
Based on a maximum power dissipation of 0.43W (1.7V x 250mA) with an ambient of 70°C, the resulting
junction temperature will be:
θ TJUNC = TAMB + PD ( )JA
= 70°C + 0.43W (80°C/W)
= 70°C + 37°C = 103°C
Thermal characteristics were measured using a double-sided board with two square inches of copper area
connected 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
temperature.
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
CMPWR101
with
an
overall
θ
JA
of
100°C/W
which
allows
up
to
500mW
to
be
safely
dissipated.
Rev. 3 | Page 9 of 12 | www.onsemi.com
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