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GM1117-1.5TB3T 参数 Datasheet PDF下载

GM1117-1.5TB3T图片预览
型号: GM1117-1.5TB3T
PDF下载: 下载PDF文件 查看货源
内容描述: 1.0A低压差精密线性稳压器 [1.0A LOW DROPOUT PRECISION LINEAR REGULATORS]
分类和应用: 稳压器
文件页数/大小: 13 页 / 228 K
品牌: GAMMA [ GAMMA MICROELECTRONICS INC. ]
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Power Management  
A
MICROELECTRONICS  
GM1117  
1.0A LOW DROPOUT PRECISION LINEAR REGULATORS  
The thermal characteristics of an IC depend four fac-  
tors:  
1. Maximum Ambient Temperature T (°C)  
A
2. Power Dissipation P (Watts)  
D
3. Maximum Junction Temperature T (°C)  
J
4. Thermal Resistance Junction to ambient R  
JA  
Q
(°C/W)  
The relationship of these four factors is expressed by  
equation (1):  
T = T + P X R  
J A D  
........(1)  
QJA  
Maximum ambient temperature and power dissipa-  
tion are determined by the design while the maximum  
junction temperature and thermal resistance depend  
on the manufacturer and the package type.  
The maximum power dissipation for a regulator is ex-  
pressed by equation (2):  
P
= { V - V  
IN(max)  
} I  
OUT(min) OUT(max)  
+ V  
I ........(2)  
IN(max) Q  
D(max)  
where:  
V
is the maximum input voltage,  
IN(max)  
V
is the minimum output voltage,  
OUT(min)  
I
is the maximum output current  
OUT(max)  
I is the maximum quiescent current at I  
Q
.
OUT(max)  
A heat sink effectively increases the surface area of  
the package to improve the flow of heat away from  
the IC into the air. Each material in the heat flow path  
between the IC and the environment has a thermal re-  
sistance. Like series electrical resistances, these re-  
sistance are summed to determine R , the total  
QJA  
thermal resistance between the junction and the air.  
This is expressed by equation (3):  
R
QJA  
= R + R + R  
QJC QCS  
........(3)  
QSA  
Where all of the following are in °C/W:  
R
R
R
is thermal resistance of junction to case,  
is thermal resistance of case to heat sink,  
is thermal resistance of heat sink to ambient air  
QJC  
QCS  
QSA  
The value for R  
is calculated using equation (3)  
QJA  
and the result can be substituted in equation (1). The  
value for R is 3.5°C/W for a given package type  
QJC  
based on an average die size. For a high current reg-  
ulator such as the GM1117 the majority of the heat is  
generated in the power transistor section.  
8