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参数资料
| 型号： | MIC2171BU |
| 厂商： | Micrel Inc |
| 文件页数： | 6/12页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG 2.5A TO263-5 |
| 标准包装： | 50 |
| 类型： | 降压（降压），升压（升压），反相，Cuk |
| 输出数： | 1 |
| 输入电压： | 3 V ~ 40 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz |
| 电流 - 输出： | 2.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | TO-263-6，D²Pak（5 引线+接片），TO-263BA |
| 包装： | 管件 |
| 供应商设备封装： | TO-263-5 |
Micrel, Inc.
Application Information
Soft Start
A diode-coupled capacitor from COMP to circuit ground
slows the output voltage rise at turn on (Figure 3).
MIC2171
the losses of the power switch driver circuitry. The dc
losses are calculated from the supply voltage (V IN ) and
device supply current (I Q ).The MIC2171 supply current is
almost constant regardless of the supply voltage (see
“Electrical Characteristics”). The driver section losses
V IN
IN
MIC2171
COMP
(not including the switch) are a function of supply
voltage, power switch current, and duty cycle.
P (bias+driver) = (V IN I Q ) + (V IN(min) x I SW x ? I IN )
where:
P (bias+driver) = device operating losses
V IN(min) = supply voltage = V IN – V SW
D1
D2
C1
R1
C2
I Q = typical quiescent supply current
I CL = power switch current limit
? I IN = typical supply current increase
As a practical example refer to Figure 1.
Figure 3. Soft Start
The additional time it takes for the error amplifier to
charge the capacitor corresponds to the time it takes the
output to reach regulation. Diode D1 discharges C1
when V IN is removed.
V IN = 5.0V
I Q = 0.007A
I CL = 2.21A
δ = 66.2% (0.662)
Current Limit
V IN
IN
then:
V IN(min) = 5.0V – (2.21 x 0.37) = 4.18V
P (bias+driver) = (5 x 0.007) + (4.18 x 2.21 x 0.009)
MIC2171
SW
P (bias+driver) = 0.1W
Power switch dissipation calculations are greatly
FB
V OU T
simplified by making two assumptions which are usually
GND
COMP
fairly accurate. First, the majority of losses in the power
switch are due to on-losses. To find these losses, assign
C2 Note: Input and not common
Q1
R1
C1
R2
R3 I C L 0.6V/R2
output
returns
a resistance value to the collector/emitter terminals of
the device using the saturation voltage versus collector
current curves (see Typical Performance Character-
istics). Power switch losses are calculated by modeling
the switch as a resistor with the switch duty cycle
V OUT + V F ? V IN(min)
Figure 4. Current Limit
The maximum current limit of the MIC2171 can be
reduced by adding a voltage clamp to the COMP output
(Figure 4). This feature can be useful in applications
requiring either a complete shutdown of Q1’s switching
action or a form of current fold-back limiting. This use of
the COMP output does not disable the oscillator,
amplifiers or other circuitry, therefore, the supply current
is never less than approximately 5mA.
Thermal Management
Although the MIC2171 family contains thermal protection
circuitry, for best reliability, avoid prolonged operation
with junction temperatures near the rated maximum.
The junction temperature is determined by first
calculating the power dissipation of the device. For the
MIC2171, the total power dissipation is the sum of the
device operating losses and power switch losses.
The device operating losses are the dc losses
associated with biasing all of the internal functions plus
modifying the average power dissipation.
P SW = (I SW ) 2 R SW δ
where:
δ = duty cycle
δ =
V OUT + V F
V SW = I CL (R SW )
V OUT = output voltage
V F = D1 forward voltage drop at I OUT
From the Typical performance Characteristics:
R SW = 0.37 ?
then:
P SW = (2.21) 2 × 0.37 × 0.662
P SW = 1.2W
P (total) = 1.2 + 0.1
P (total) = 1.3W
May 2007
6
M9999-051107
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2171BU TR | 功能描述:IC REG MULTI CONFIG 2.5A TO263-5 RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
| MIC2171WT | 功能描述:直流/直流开关调节器 2.5A 100kHz Switching Regulator (ROHS Compliant) 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 |
| MIC2171WU | 功能描述:直流/直流开关调节器 2.5A 100kHz Switching Regulator (ROHS Compliant) 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 |
| MIC2171WU TR | 功能描述:直流/直流开关调节器 2.5A 100kHz Switching Regulator (ROHS Compliant) 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 |
| MIC2171WU-TR | 功能描述:Buck, Boost, Cuk, Flyback, Forward Converter Switching Regulator IC Positive or Negative, Isolation Capable Adjustable 1 Output 2.5A (Switch) TO-263-6, D2Pak (5 Leads + Tab), TO-263BA 制造商:microchip technology 系列:- 包装:剪切带（CT） 零件状态:有效 功能:升压，降压，升压/降压 输出配置:正或负，可提供隔离 拓扑:降压，升压，Cuk，反激，正激转换器 输出类型:可调式 输出数:1 电压 - 输入（最小值）:3V 电压 - 输入（最大值）:40V 电压 - 输出（最小值/固定）:- 电压 - 输出（最大值）:65V（开关） 电流 - 输出:2.5A（开关） 频率 - 开关:100kHz 同步整流器:无 工作温度:-40°C ~ 85°C（TA） 安装类型:表面贴装 封装/外壳:TO-263-6，D2Pak（5 引线+接片），TO-263BA 供应商器件封装:TO-263-5 标准包装:1 |
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