参数资料
| 型号： | MIC2169BMM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 9/15页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 10-MSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 550kHz |
| 占空比： | 92% |
| 电源电压： | 3 V ~ 14.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | MIC2169BMMTR MIC2169BMMTR-ND |
MIC2169
I PK = I OUT ( max ) + 0.5 × I PP
The RMS inductor current is used to calculate the I 2 × R
Micrel
I PP = peak-to-peak inductor ripple current
The total output ripple is a combination of the ESR output
capacitance. The total ripple is calculated below:
3 ? I OUT ( max ) ?
(
? I PP × (1 ? D) ?
? ? + I PP × R ESR
? C OUT S ?
losses in the inductor.
I INDUCTOR(rms) = I OUT ( max ) × 1 +
1 ? I P ?
? ?
2
Δ V OUT =
× f
2
)
2
I PP
I C
12
P DISS(C OUT ) = I C × R ESR(C OUT )
Maximizing ef?ciency requires the proper selection of core
material and minimizing the winding resistance. The high
frequency operation of the MIC2169 requires the use of fer-
rite materials for all but the most cost sensitive applications.
Lower cost iron powder cores may be used but the increase
in core loss will reduce the ef ? ciency of the power supply.
This is especially noticeable at low output power. The winding
resistance decreases ef ? ciency at the higher output current
levels. The winding resistance must be minimized although
this usually comes at the expense of a larger inductor. The
power dissipated in the inductor is equal to the sum of the
core and copper losses. At higher output loads, the core
losses are usually insigni ? cant and can be ignored. At lower
output currents, the core losses can be a signi ? cant con-
tributor. Core loss information is usually available from the
magnetics vendor. Copper loss in the inductor is calculated
by the equation below:
P INDUCTORCu = I INDUCTOR(rms) 2 × R WINDING
The resistance of the copper wire, R WINDING , increases with
temperature. The value of the winding resistance used should
be at the operating temperature:
R WINDING(hot) = R WINDING(20 ° C) × ( 1 + 0.0042 × (T HOT ? T 20 ° C ) )
where:
T HOT = temperature of the wire under operating load
T 20°C = ambient temperature
R WINDING(20°C) is room temperature winding resistance (usu-
ally speci ? ed by the manufacturer)
Output Capacitor Selection
where:
D = duty cycle
C OUT = output capacitance value
f S = switching frequency
The voltage rating of capacitor should be twice the voltage for
a tantalum and 20% greater for an aluminum electrolytic.
The output capacitor RMS current is calculated below:
=
OUT(rms)
The power dissipated in the output capacitor is:
OUT(rms)2
Input Capacitor Selection
The input capacitor should be selected for ripple current rating
and voltage rating. Tantalum input capacitors may fail when
subjected to high inrush currents, caused by turning the input
supply on. To maximize reliability, tantalum input capacitor
voltage rating should be at least two times the maximum in-
put voltage. Aluminum electrolytic, OS-CON, and multilayer
polymer ? lm capacitors can handle the higher inrush currents
without voltage derating. The input voltage ripple will primar-
ily depends upon the input capacitor ’s ESR. The peak input
current is equal to the peak inductor current, so:
Δ V IN = I INDUCTOR(peak) × R ESR(C IN )
The input capacitor must be rated for the input current ripple.
The RMS value of input capacitor current is determined at
the maximum output current. Assuming the peak-to-peak
inductor ripple current is low:
The output capacitor values are usually determined capacitors
ESR (equivalent series resistance). Voltage and RMS current
I C IN (rms) ≈ I OUT ( max ) ×
D × (1 ? D)
capability are two other important factors to consider when
The power dissipated in the input capacitor is:
selecting the output capacitor. Recommended capacitors are
tantalum, low-ESR aluminum electrolytics, and POSCAPS.
P DISS(C IN )
= I C
IN (rms)
2
× R ESR(C IN )
The output capacitor ’s ESR is usually the main cause of
output ripple. The output capacitor ESR also affects the
overall voltage feedback loop from stability point of view. See:
“Feedback Loop Compensation” section for more information.
The maximum value of ESR is calculated:
Voltage Setting Components
The MIC2169 requires two resistors to set the output voltage
as shown in Figure 2.
R ESR ≤
Δ V OUT
I PP
where:
V OUT = peak-to-peak output voltage ripple
March 2009
9
M9999-032409
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相关代理商/技术参数 |
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| MIC2169BYMM | 功能描述:DC/DC 开关控制器 500kHz PWM Synchronous Buck Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MIC2169BYMM TR | 功能描述:DC/DC 开关控制器 500kHz PWM Synchronous Buck Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MIC2169BYMME | 功能描述:直流/直流开关转换器 Synchronous Step Down Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MIC2169BYMME TR | 功能描述:直流/直流开关转换器 Synchronous Step Down Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MIC2169MM | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:500 KHZ PWM SYNCHRONOUS BUCK CONTROL IC |
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