CM3002 Datasheet, PDF (14/17 Pages) California Micro Devices Corp – Micropower 1.0A Low Dropout CMOS Regulators

CM3002
Performance Information (cont’d)
Typical Thermal Characteristics
The overall junction to ambient thermal resistance
(θ_JA) for device power dissipation (P_D) consists prima-
rily of two paths in series. The first path is the junction
to the case (θ_JC) which is defined by the package style,
and the second path is case to ambient (θ_CA) 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_JUNC = T_AMB + P_D ∗ (θ_JC) + P_D ∗ (θ_CA)
= T_AMB + P_D ∗ (θ_JA)
The CM3002 family uses thermally enhanced SOIC
and MSOP packages 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 θ_JA is about 50° C/W for
the SOIC package and 70° C/W for the MSOP pack-
age.
Based on a maximum power dissipation of 0.8W (Load
x Vin-Vout = 1.0A x [3.3V-2.5V]) with an ambient of
70° C, the resulting junction temperature for a SOIC-
packaged device will be:
T_JUNC = T_AMB + P_D ∗ (θ_JA)
= 70° C + 0.8W ∗ (50° C/W)
= 70° C + 40° C = 110° 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 a junction
temperature of 125° C are presented in Figure 1,
Figure 2, Figure 3 and Figure 4. They were performed
under light load conditions (5mA); this allows the ambi-
ent 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 typically provide a CM3002 device
packaged in a SOIC package with an overall θ_JA of
50° C/W, which allows up to 0.8W to be dissipated
safely.
Please consult CAMD Technical Support for assistance
with thermal analysis of the CM3002 family of regula-
tors with respect to a specific application.
Output Voltage with Temperature (5mA Load)
Ground Current with Temperature (No Load)
1.54
1.52
1.50
1.48
1.46
0
25
50
75 100 125
Junction Temperature [°C]
700
600
500
400
300
200
100
0
0
25
50
75 100 125
Junction Temperature [°C]
Figure 1. CM3002-15SA/SF Performance vs. Temperature
© 2004 California Micro Devices Corp. All rights reserved.
14 430 N. McCarthy Blvd., Milpitas, CA 95035-5112 ▲ Tel: [phone]
▲ Fax: [phone] ▲ www.calmicro.com
08/16/04