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参数资料
| 型号： | MIC2171BU |
| 厂商： | Micrel Inc |
| 文件页数： | 7/12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.
The junction temperature for any semiconductor is
calculated using the following:
MIC2171
Discontinuous mode is preferred because the feedback
control of the converter is simpler.
where:
T J = T A + P (total) θ JA
When L1 discharges its current completely during the
MIC2171 off-time, it is operating in discontinuous mode.
T J = junction temperature
T A = ambient temperature (maximum)
P (total) = total power dissipation
θ JA = junction to ambient thermal resistance
For the practical example:
T A = 70°C
θ JA = 45°C/W (TO-220)
L1 is operating in continuous mode if it does not
discharge completely before the MIC2171 power switch
is turned on again.
Discontinuous Mode Design
Given the maximum output current, solve equation (1) to
determine whether the device can operate in
discontinuous mode without initiating the internal device
current limit.
? ? V IN(min) δ
? ?
I OUT ≤
V OUT + V F ? V IN(min)
then:
T J = 70 + (1.24 × 45)
T J = 126°C
This junction temperature is below the rated maximum of
150°C.
Grounding
Refer to Figure 5. Heavy lines indicate high current
paths.
(1)
(1a)
where:
? I CL ?
? 2 ?
V OUT
δ =
V OUT + V F
I CL = internal switch current limit
V IN
IN
MIC2171
SW
I CL = 2.5A when δ < 50%
I CL = 1.67 (2 – δ ) when δ ≥ 50%
(Refer to Electrical Characteristics.)
I OUT = maximum output current
GND
FB
VC
V IN(min) = minimum input voltage = V IN – V SW
δ = duty cycle
V OUT = required output voltage
V F = D1 forward voltage drop
Single point ground
Figure 5. Single Point Ground
For the example in Figure 1.
I OUT = 0.25A
I CL = 1.67 (2–0.662) = 2.24A
A single point ground is strongly recommended for
proper operation.
The signal ground, compensation network ground, and
feed-back network connections are sensitive to minor
voltage variations. The input and output capacitor
grounds and power ground conductors will exhibit
then:
V IN(min) = 4.18V
δ = 0.662
V OUT = 12.0V
V F = 0.36V (@ .26A, 70°C)
? × 4.178 × 0.662
?
voltage drop when carrying large currents. Keep the
sensitive circuit ground traces separate from the power
ground traces. Small voltage variations applied to the
sensitive circuits can prevent the MIC2171 or any
I OUT ≤
? 2.235 ?
? 2 ?
12
(V IN δ ) 2
switching regulator from functioning properly.
Boost Conversion
Refer to Figure 1 for a typical boost conversion
application where a +5V logic supply is available but
+12V at 0.25A is required.
The first step in designing a boost converter is
determining whether inductor L1 will cause the converter
to operate in either continuous or discontinuous mode.
I OUT ≤ 0.258A
This value is greater than the 0.25A output current
requirement, so we can proceed to find the minimum
inductance value of L1 for discontinuous operation at
P OUT .
(2) L1 ≥
2P OUT f SW
May 2007
7
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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