RT9172F-14CG Ver la hoja de datos (PDF) - Richtek Technology

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RT9172F-14CG

1.4V, 3A fixed output voltage LDO regulator

Richtek Technology 

Preliminary

RT9172

Heatsinking TO-220Packages

The thermal resistance of a TO-220 package can be

reduced by attaching it to a heat sink or a copper plane

on a PC board. If a copper plane is to be used, the

values of θJA will be same as shown in next section for

TO-263 package.

Heatsinking TO-263 and SOT-223 Packages

The TO-263 and SOT-223 packages use the copper

plane on the PCB as a heatsink. The tab of these

packages are soldered to the copper plane for heat

sinking. Fig.4 shows a curve for θJA of TO-263 package

for different copper area sizes, using a typical PCB with

1 ounce copper and no solder mask over the copper

area for heat sinking.

θJA vs. Copper (1 Ounce) Area for TO-263

200

180

160

4W

140

120

100

2.5W

80

60

40

1W

20

0

0

0.5

1

1.5

2

2.5

3

Copper Foil Area (SQ. IN.)

Fig. 4

As shown in the figure, increasing the copper area

beyond 1 square inch produces very little

improvement. The minimum value for θJA for the TO-

263 package mounted to a PCB is 32°C/W.

DS9172-03 April 2002

www.richtek-ic.com.tw

9

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