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| 型号： | MIC4576BU TR |
| 厂商： | Micrel Inc |
| 文件页数： | 6/8页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 3A TO263-5 |
| 标准包装： | 750 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.23 V ~ 33 V |
| 输入电压： | 4 V ~ 36 V |
| 频率 - 开关： | 200kHz |
| 电流 - 输出： | 3A |
| 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： | 带卷 (TR) |
| 供应商设备封装： | TO-263-5 |
| 其它名称： | MIC4576BUTR |
MIC4576
Functional Description
The MIC4576 is a variable duty cycle switch-mode regulator
with an internal power switch. Refer to the block diagrams.
Supply Voltage
The MIC4576 operates from a +4V to +36V unregulated
input. Highest ef?ciency operation is from a supply voltage
around +15V.
Enable/Shutdown
The shutdown ( SHDN ) input is TTL compatible. Ground the
input if unused. A logic-low enables the regulator. A logic-
high shuts down the internal regulator which reduces the
current to typically 50μA.
Feedback
Fixed versions of the regulator have an internal resistive
divider from the feedback ( FB ) pin. Connect FB directly to
the output line.
Adjustable versions require an external resistive voltage
divider from the output voltage to ground, connected from
the 1.23V tap to FB .
Duty Cycle Control
A ?xed-gain error ampli?er compares the feedback signal
with a 1.23V bandgap voltage reference. The resulting error
ampli?er output voltage is compared to a 200kHz sawtooth
waveform to produce a voltage controlled variable duty cycle
output.
Applications Information
The applications circuits that follow have been constructed
and tested. Refer to Application Note 15 for additional in-
formation, including ef?ciency graphs and manufacturer ’s
addresses and telephone numbers for most circuits.
Micrel, Inc.
A higher feedback voltage increases the error ampli?er output
voltage. A higher error ampli?er voltage (comparator inverting
input) causes the comparator to detect only the peaks of the
sawtooth, reducing the duty cycle of the comparator output.
A lower feedback voltage increases the duty cycle.
Output Switching
When the internal switch is on, an increasing current ?ows
from the supply V IN, through external storage inductor L1, to
output capacitor C OUT and the load. Energy is stored in the
inductor as the current increases with time.
When the internal switch is turned off, the collapse of the
magnetic ?eld in L1 forces current to ?ow through fast recovery
diode D1, charging C OUT .
Output Capacitor
External output capacitor C OUT provides stabilization and
reduces ripple.
Return Paths
During the on portion of the cycle, the output capacitor and
load currents return to the supply ground. During the off
portion of the cycle, current is being supplied to the output
capacitor and load by storage inductor L1, which means that
D1 is part of the high-current return path.
For a mathematical approach to component selection and
circuit design, refer to Application Note 14.
6V to 24V
C1
470μF
35V
5
1
SHDN SW
MIC4576-3.3BT
V IN FB
GND
3
2
4
L1
33μH
D1
1N5822
3.3V/3A
C2
1000μF
16V
6V to 36V
C1
470μF
63V
5
1
SHDN SW
MIC4576-3.3BT
V IN FB
GND
3
2
4
L1
33μH
D1
MBR360
3.3V/3A
C2
1000μF
16V
C1
C2
D1
L1
L1
Nichicon
Nichicon
Motorola
Coiltronics
Bi
UPL1V471MPH, ESR = 0.046 ?
UPL1C221MPH, ESR = 0.047 ?
1N5822
PL52C-33-1000, DCR = 0.036 ?
HM77-30004, DCR = 0.045 ? , Note 2
C1
C2
D1
L1
L1
Nichicon
Nichicon
Motorola
Coiltronics
Bi
UPL1J471MRH, ESR = 0.039 ?
UPL1C102MPH, ESR = 0.047 ?
MBR360
PL52C-33-1000 DCR = 0.036
HM77-30004, DCR = 0.045 ? , Note 2
Figure 1. 6V–24V to 3.3V/3A Buck Converter
Through Hole
Figure 2. 6V–36V to 3.3V/3A Buck Converter
Through Hole
Note 2:
Surface-mount component.
MIC4576
6
March 2006
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC4576WT | 功能描述:直流/直流开关调节器 200kHz 3.0A Step-down 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 |
| MIC4576WU | 功能描述:直流/直流开关调节器 200kHz 3.0A Step-down 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 |
| MIC4576WU TR | 功能描述:直流/直流开关调节器 200kHz 3.0A Step-down 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 |
| MIC4576WUTR | 制造商:Micrel 功能描述:Conv DC-DC Single Step Down 4V to 36V |
| MIC4576WU-TR | 功能描述:Buck Switching Regulator IC Positive Adjustable 1.23V 1 Output 3A 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:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:1 电压 - 输入（最小值）:4V 电压 - 输入（最大值）:36V 电压 - 输出（最小值/固定）:1.23V 电压 - 输出（最大值）:33V 电流 - 输出:3A 频率 - 开关:200kHz 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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