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LT1054C 参数 Datasheet PDF下载

LT1054C图片预览
型号: LT1054C
PDF下载: 下载PDF文件 查看货源
内容描述: 与监管机构的开关电容电压转换器 [SWITCHED-CAPACITOR VOLTAGE CONVERTERS WITH REGULATORS]
分类和应用: 转换器开关
文件页数/大小: 26 页 / 442 K
品牌: TI [ TEXAS INSTRUMENTS ]
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SLVS033F − FEBRUARY 1990 − REVISED NOVEMBER 2004  
APPLICATION INFORMATION  
power dissipation (continued)  
At R  
of 130°C/W for a commercial plastic device, a junction temperature rise of 122°C occurs. The device  
θJA  
exceeds the maximum junction temperature at an ambient temperature of 25°C. To calculate the power  
dissipation with an external resistor (R ), determine how much voltage can be dropped across R . The  
maximum voltage loss of the LT1054 in the standard regulator configuration at 100 mA output current is 1.6 V.  
X
X
[(  
)(  
)
|
|]  
VX + 12 V * 1.6 V 1.3 ) *5 V + 4.9 V  
(10)  
and  
4.9 V  
4.4 100 mA  
RX +  
+ 11 W  
(
)(  
)
(11)  
The resistor reduces the power dissipated by the LT1054 by (4.9 V)(100 mA) = 490 mW. The total power  
dissipated by the LT1054 is equal to (940 mW − 490 mW) = 450 mW. The junction-temperature rise is 58°C.  
Although commercial devices are functional up to a junction temperature of 125°C, the specifications are tested  
to a junction temperature of 100°C. In this example, this means limiting the ambient temperature to 42°C. To  
allow higher ambient temperatures, the thermal resistance numbers for the LT1054 packages represent  
worst-case numbers, with no heat sinking and still air. Small clip-on heat sinks can be used to lower the thermal  
resistance of the LT1054 package. Airflow in some systems helps to lower the thermal resistance. Wide printed  
circuit board traces from the LT1054 leads help remove heat from the device. This is especially true for plastic  
packages.  
10 V  
100 kΩ  
1N4002  
1
8
7
100-kΩ  
V
CC  
FB/SD  
CAP+  
GND  
Speed Control  
+
5 µF  
2
3
OSC  
LT1054  
+
+
6
5
10 µF  
V
REF  
+
1N5817  
4
V
OUT  
CAP−  
Tach  
Motor  
NOTE: Motor-Tach is Canon CKT26-T5-3SAE.  
Pin numbers shown are for the P package.  
Figure 18. Motor-Speed Servo  
14  
POST OFFICE BOX 655303 DALLAS, TEXAS 75265  
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