www.德州仪器.com
P
D
最大值
(
5
2.5
)
V x 1 一个
2.5 W
(7)
R
θ
JA
最大值
(125
55)
°
C
2.5 W
28
°
C
W
(8)
15
20
25
30
35
40
0.1 1 10 100
铜 散热器 范围 − cm
2
− 热的 阻抗 −
θ
JA
R c/w
°
非 空气 流动
150 lfm
250 lfm
1 oz. 铜
电源 平面
1 oz. 铜
地面 平面
2 oz. 铜 焊盘 垫子
和 25 热的 vias
热的 vias, 0.3 mm
直径, 1,5 mm 程度
TPS72501
tps72515,tps72516
tps72518,tps72525
SLVS341D–MAY2002–REVISEDMARCH2004
thermalinformation(持续)
toillustrate,thetps72525inaddpakpackagewaschosen.forthisexample,theaverageinputvoltageis5
v,theoutputvoltageis2.5v,theaverageoutputcurrentis1a,theambienttemperature55
°
c,theairflowis
150lfm,andtheoperatingenvironmentisthesameasdocumentedbelow.neglectingthequiescentcurrent,
themaximumaveragepoweris:
SubstitutingT
J
maxforT
J
intoequation6givesequation8:
fromfigure21,ddpakthermalresistancevscopperheatsinkarea,thegroundplaneneedstobe1cm
2
为
theparttodissipate2.5w.theoperatingenvironmentusedinthecomputermodeltoconstructfigure21
consistedofastandardjedechigh-kboard(2s2p)witha1oz.internalcopperplaneandgroundplane.这
packageissolderedtoa2oz.copperpad.thepadistiedthroughthermalviastothe1oz.groundplane.
figure22showsthesideviewoftheoperatingenvironmentusedinthecomputermodel.
figure21.ddpakthermalresistancevscopperheatsinkarea
figure22.ddpakthermalresistance
12