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参数资料
| 型号： | MIC33030-4YHJ TR |
| 厂商： | Micrel Inc |
| 文件页数： | 13/18页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 1.2V 0.4A 10HMLF |
| 标准包装： | 1 |
| 系列： | HyperLight Load® |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 1.2V |
| 输入电压： | 2.7 V ~ 5.5 V |
| PWM 型： | 混合物 |
| 频率 - 开关： | 8MHz |
| 电流 - 输出： | 400mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFQFN 裸露焊盘，10-MLF? |
| 包装： | 标准包装 |
| 供应商设备封装： | 10-MLF?（2.5x2） |
| 其它名称： | 576-3719-6 |
P DISS = P OUT ? ( ? 1 )
Micrel Inc.
Power Dissipation Considerations
As with all power devices, the ultimate current rating of
the output is limited by the thermal properties of the
package and the PCB it is mounted on. There is a
simple, ohms law type relationship between thermal
resistance, power dissipation and temperature which are
analogous to an electrical circuit:
From this simple circuit we can calculate Vx if we know
Isource, Vz and the resistor values, Rxy and Ryz using
the equation:
Vx = Isource ? ( Rxy + Ryz ) + Vz
Thermal circuits can be considered using these same
rules and can be drawn similarly replacing current
sources with Power dissipation (in Watts), Resistance
with Thermal Resistance (in o C/W) and Voltage sources
with temperature (in o C):
MIC33030
Since effectively all of the power loss in the converter is
dissipated within the MIC33030 package, P DISS can be
calculated thus:
1
η
Where η = Efficiency taken from efficiency curves
R θ JC and R θ JA are found in the operating ratings section
of the datasheet.
Example:
A MIC33030 is intended to drive a 300mA load at 1.8V
and is placed on a printed circuit board which has a
ground plane area of at least 25mm square. The Voltage
source is a Li-ion battery with a lower operating
threshold of 3V and the ambient temperature of the
assembly can be up to 50 o C.
Summary of variables:
I OUT = 0.3A
V OUT = 1.8V
V IN = 3V to 4.2V
T AMB = 50 o C
R θ JA = 76 o C/W from Datasheet
η @ 300mA = 75% (worst case with V IN =4.2V from the
Typical Characteristics Efficiency vs. Load graphs)
P DISS = 1 . 8 ? 0 . 3 ? (
1
0 . 75
? 1 ) = 0.18W
The worst case switch and inductor resistance will
increase at higher temperatures, so a margin of 20% can
be added to account for this:
P DISS = 0.18 x 1.2 = .216W
Now replacing the variables in the equation for Vx, we
can find the junction temperature (T J ) from power
dissipation, ambient temperature and the known thermal
resistance of the PCB (R θ CA ) and the package (R θ JC ):
T J = P DISS ? ( R θ JC + R θ CA ) + T AMB
As can be seen in the diagram, total thermal resistance
R θ JA = R θ JC + R θ CA . Hence this can also be written:
T J = P DISS ? ( R θ JA ) + T AMB
Therefore:
T J = 0.216W. (76 o C/W) + 50 o C
T J = 66 o C
This is well below the maximum 125 o C.
February 2011
13
M9999-020311-C
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC33030-AYHJ | 制造商:Micrel 功能描述:DC-DC Converter, Step Down 2.7V to 5.5V |
| MIC33030-AYHJ TR | 功能描述:直流/直流开关调节器 8MHz 400mA Internal Inductor Buck Regulator with HyperLight Load RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MIC33030-AYHJ-TR | 功能描述:Buck Switching Regulator IC Positive Adjustable 0.7V 1 Output 400mA 10-TFQFN Exposed Pad, 10-MLF? 制造商:microchip technology 系列:HyperLight Load? 包装:剪切带（CT） 零件状态:停产 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:1 电压 - 输入（最小值）:2.7V 电压 - 输入（最大值）:5.5V 电压 - 输出（最小值/固定）:0.7V 电压 - 输出（最大值）:3.6V 电流 - 输出:400mA 频率 - 开关:8MHz 同步整流器:是 工作温度:-40°C ~ 125°C （TJ） 安装类型:表面贴装 封装/外壳:10-TFQFN 裸露焊盘，10-MLF? 供应商器件封装:10-MLF?（2.5x2） 标准包装:1 |
| MIC33030-GYHJ | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:8MHz 400mA Internal Inductor Buck Regulator with HyperLight Load |
| MIC33030-GYHJ T5 | 功能描述:直流/直流开关调节器 8MHz 400mA Internal Inductor Buck Regulator with HyperLight Load RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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