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| 型号： | MIC2194BM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 9/10页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 8-SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 100% |
| 电源电压： | 2.9 V ~ 14 V |
| 降压： | 是 |
| 升压： | 是 |
| 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 ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 其它名称： | MIC2194BMTR MIC2194BMTR-ND |
MIC2194
Micrel
MIC2194
Voltage
Amplifier
Pin 2
V OUT
R1
R2
Under heavy output loads the significant contributors to
power loss are (in approximate order of magnitude):
? Resistive on time losses in the MOSFET
? Switching transition losses in the MOSFET
? Inductor resistive losses
? Current sense resistor losses
? Input capacitor resistive losses (due to the capacitors
V REF
1.245V
Figure 5
The output voltage is determined by:
ESR)
To minimize power loss under heavy loads:
? Use low on-resistance MOSFETs. Use low threshold
logic level MOSFETs when the input voltage is below
5V. Multiplying the gate charge by the on-resistance
V OUT = V REF × 1 +
R1
R 2
gives a figure of merit, providing a good balance
between low load and high load efficiency.
? Slow transition times and oscillations on the voltage
V REF × R 1
Where: V REF for the MIC2194 is typically 1.245V.
Lower values of R1 are preferred to prevent noise from
appearing on the FB pin. A typically recommended value is
10k ? . If R1 is too small in value it will decrease the efficiency
of the power supply, especially at low output loads.
Once R1 is selected, R2 can be calculated with the following
formula:
R 2 =
V OUT – V REF
Efficiency Considerations
Efficiency is the ratio of output power to input power. The
difference is dissipated as heat in the buck converter. Under
light output load, the significant contributors are:
? The V IN supply current, which includes the current
required to switch the external MOSFET.
? Core losses in the output inductor.
To maximize efficiency at light loads:
? Use a low gate charge MOSFET or use the smallest
MOSFET, which is still adequate for maximum output
current.
? Use a ferrite material for the inductor core, which has
less core loss than an MPP or iron power core.
and current waveforms dissipate more power during
the turn on and turn off of the MOSFET. A clean
layout will minimize parasitic inductance and capaci-
tance in the gate drive and high current paths. This
will allow the fastest transition times and waveforms
without oscillations. Low gate charge MOSFETs will
transition faster than those with higher gate charge
requirements.
? For the same size inductor, a lower value will have
fewer turns and therefore, lower winding resistance.
However, using too small of a value will require more
output capacitors to filter the output ripple, which will
force a smaller bandwidth, slower transient response
and possible instability under certain conditions.
? Lowering the current sense resistor value will de-
crease the power dissipated in the resistor. However,
it will also increase the overcurrent limit and will
require larger MOSFETs and inductor components.
? Use low ESR input capacitors to minimize the power
dissipated in the capacitors ESR.
April 2005
9
MIC2194
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2194YM | 功能描述:DC/DC 开关控制器 SO-8 3V Buck Contoller (Lead Free) 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 |
| MIC2194YM TR | 功能描述:DC/DC 开关控制器 SO-8 3V Buck Contoller (Lead Free) 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 |
| MIC2196 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:400kHz SO-8 Boost Control IC |
| MIC2196_08 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:400kHz SO-8 Boost Control IC |
| MIC2196BM | 功能描述:IC REG CTRLR BST FLYBK PWM 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
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