参数资料
| 型号： | MIC5219-2.9YM5 TR |
| 厂商： | Micrel Inc |
| 文件页数： | 10/14页 |
| 文件大小： | 0K |
| 描述： | IC REG LDO 2.9V .5A SOT23-5 |
| 标准包装： | 1 |
| 稳压器拓扑结构： | 正，固定式 |
| 输出电压： | 2.9V |
| 输入电压： | 最高 12V |
| 电压 - 压降（标准）： | 0.35V @ 500mA |
| 稳压器数量： | 1 |
| 电流 - 输出： | 500mA |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SC-74A，SOT-753 |
| 供应商设备封装： | SOT-23-5 |
| 包装： | 标准包装 |
| 产品目录页面： | 1098 (CN2011-ZH PDF) |
| 其它名称： | 576-2764-6 |
( T J ( max ) ? T A )
θ JA
( 125 ° C ? 25 ° C )
P D ( max ) =
(
)
Avg.P D = ?
? V IN – V OUT I OUT + V IN I GND
V IN ( max ) =
= 5 . 683V
? ( 8V – 5V ) 500mA + 8V × 20mA
? % DC ?
? 100 ?
? % Duty Cycle ?
?
?
455mW = ? ? 1.66W
0.274 =
Micrel, Inc.
Peak Current Applications
The MIC5219 is designed for applications where high start-up
currents are demanded from space constrained regulators.
This device will deliver 500mA start-up current from a SOT-
23-5 or MM8 package, allowing high power from a very low
profile device. The MIC5219 can subsequently provide output
current that is only limited by the thermal characteristics of
the device. You can obtain higher continuous currents from
the device with the proper design. This is easily proved with
some thermal calculations.
If we look at a specific example, it may be easier to follow.
The MIC5219 can be used to provide up to 500mA continuous
output current. First, calculate the maximum power dissipa -
tion of the device, as was done in the thermal considerations
section. Worst case thermal resistance ( θ JA = 220°C/W for
the MIC5219-x.xBM5), will be used for this example.
P D ( max ) =
Assuming a 25°C room temperature, we have a maximum
power dissipation number of
220 ° C / W
P D (max) = 455mW
Then we can determine the maximum input voltage for a
5-volt regulator operating at 500mA, using worst case ground
current.
P D (max) = 455mW = (V IN – V OUT ) I OUT + V IN I GND
I OUT = 500mA
V OUT = 5V
I GND = 20mA
455mW = (V IN – 5V) 500mA + V IN × 20mA
2.995W = 520mA × V IN
2 . 955W
520mA
Therefore, to be able to obtain a constant 500mA output cur -
rent from the 5219-5.0BM5 at room temperature, you need
extremely tight input-output voltage differential, barely above
the maximum dropout voltage for that current rating.
You can run the part from larger supply voltages if the proper
precautions are taken. Varying the duty cycle using the en -
able pin can increase the power dissipation of the device by
maintaining a lower average power figure. This is ideal for
applications where high current is only needed in short bursts.
Figure 1 shows the safe operating regions for the MIC5219-x.
xBM5 at three different ambient temperatures and at differ -
ent output currents. The data used to determine this figure
assumed a minimum footprint PCB design for minimum heat
sinking. Figure 2 incorporates the same factors as the first
figure, but assumes a much better heat sink. A 1" square cop -
per trace on the PC board reduces the thermal resistance of
the device. This improved thermal resistance improves power
dissipation and allows for a larger safe operating region.
Figures 3 and 4 show safe operating regions for the MIC5219-x.
MIC5219
xBMM, the power MSOP package part. These graphs show
three typical operating regions at different temperatures. The
lower the temperature, the larger the operating region. The
graphs were obtained in a similar way to the graphs for the
MIC5219-x.xBM5, taking all factors into consideration and
using two different board layouts, minimum footprint and 1"
square copper PC board heat sink. (For further discussion
of PC board heat sink characteristics, refer to “Application
Hint 17, Designing PC Board Heat Sinks” .)
The information used to determine the safe operating regions
can be obtained in a similar manner such as determining
typical power dissipation, already discussed. Determining
the maximum power dissipation based on the layout is the
first step, this is done in the same manner as in the previous
two sections. Then, a larger power dissipation number multi -
plied by a set maximum duty cycle would give that maximum
power dissipation number for the layout. This is best shown
through an example. If the application calls for 5V at 500mA
for short pulses, but the only supply voltage available is
8V, then the duty cycle has to be adjusted to determine an
average power that does not exceed the maximum power
dissipation for the layout.
? % DC ?
? 100 ?
455mW = ?
100
% Duty Cycle
100
% Duty Cycle Max = 27.4%
With an output current of 500mA and a three-volt drop across
the MIC5219-xxBMM, the maximum duty cycle is 27.4%.
Applications also call for a set nominal current output with a
greater amount of current needed for short durations. This is a
tricky situation, but it is easily remedied. Calculate the average
power dissipation for each current section, then add the two
numbers giving the total power dissipation for the regulator.
For example, if the regulator is operating normally at 50mA,
but for 12.5% of the time it operates at 500mA output, the
total power dissipation of the part can be easily determined.
First, calculate the power dissipation of the device at 50mA.
We will use the MIC5219-3.3BM5 with 5V input voltage as
our example.
P D × 50mA = (5V – 3.3V) × 50mA + 5V × 650μA
P D × 50mA = 173mW
However, this is continuous power dissipation, the actual
on-time for the device at 50mA is (100%-12.5%) or 87.5%
of the time, or 87.5% duty cycle. Therefore, P D must be mul -
tiplied by the duty cycle to obtain the actual average power
dissipation at 50mA.
June 2009
10
M0371-061809
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC5219-3.0BM5 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| MIC5219-3.0BM5 TR | 功能描述:IC REG LDO 3V .5A SOT23-5 RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:500 系列:- 稳压器拓扑结构:正，固定式 输出电压:12V 输入电压:14.5 V ~ 35 V 电压 - 压降（标准）:- 稳压器数量:1 电流 - 输出:500mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:TO-205AD，TO-39-3 金属罐 供应商设备封装:TO-39 包装:散装 其它名称:*LM78M12CH*LM78M12CH/NOPBLM78M12CH |
| MIC5219-3.0BML | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500mA-Peak Output LDO Regulator |
| MIC5219-3.0BML TR | 功能描述:IC REG LDO 3V .5A 6-MLF RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:500 系列:- 稳压器拓扑结构:正，固定式 输出电压:12V 输入电压:14.5 V ~ 35 V 电压 - 压降（标准）:- 稳压器数量:1 电流 - 输出:500mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:TO-205AD，TO-39-3 金属罐 供应商设备封装:TO-39 包装:散装 其它名称:*LM78M12CH*LM78M12CH/NOPBLM78M12CH |
| MIC5219-3.0BMM | 功能描述:IC REG LDO 3V .5A 8-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 系列:- 标准包装:500 系列:- 稳压器拓扑结构:正，固定式 输出电压:12V 输入电压:14.5 V ~ 35 V 电压 - 压降（标准）:- 稳压器数量:1 电流 - 输出:500mA 电流 - 限制（最小）:- 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:TO-205AD，TO-39-3 金属罐 供应商设备封装:TO-39 包装:散装 其它名称:*LM78M12CH*LM78M12CH/NOPBLM78M12CH |
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