MIC5209YM-TR Datasheet, PDF (11/13 Pages) Micrel Semiconductor – 500mA Low-Noise LDO Regulator

MIC5209
Considering worst case tolerances, the power dissipation
could be as high as:
(V_IN(max) – V_OUT(max)) × I_OUT + V_IN(max) × I_GND
[(3.6V – 2.375V) × 320mA] + (3.6V × 4mA)
P_D = 407mW
Using the maximum junction temperature of 125°C and a θ_JC
of 8°C/W for the SOT-223, 25°C/W for the SO-8, or 2°C/W
for the TO-263 package, the following worst-case heat-sink
thermal resistance (θ_SA) requirements are:
θ_JA
=
T_J(max) − T_A
P_D
θ_SA = θ_JA = θ_JC
T_A
θ_JA (limit)
θ_SA SOT-223
θ_SA SO-8
θ_SA TO-263-5
40°C
209°C/W
201°C/W
184°C/W
207°C/W
50°C
184°C/W
176°C/W
159°C/W
182°C/W
60°C
160°C/W
152°C/W
135°C/W
158°C/W
75°C
123°C/W
115°C/W
98°C/W
121°C/W
Table 2. Maximum Allowable Thermal Resistance
Table 2 and Figure 6 show that the Slot-1 power supply ap-
plication can be implemented with a minimum footprint layout.
Micrel, Inc.
Figure 6 shows the necessary copper pad area to obtain
svpaeluceifiscinhTeaabt _{lsein2krethqeurimreaml} ruecshislteasnsceth(aθ_{nSA5)00vamlume2}s.ofTchoeppθ_eSrA,
according to Figure 6, and can easily be accomplished with
the minimum footprint.
70
60
50
40
30
20
10
0
0
2000
4000
6000
COPPER HEAT SINK AREA (mm²)
Figure 6. PCB Heat Sink Thermal Resistance
June 2006
11
M9999-060906