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参数资料
| 型号： | MIC4721YMM |
| 厂商： | Micrel Inc |
| 文件页数： | 11/19页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 1.5A 10MSOP |
| 标准包装： | 100 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调至 1V |
| 输入电压： | 2.7 V ~ 5.5 V |
| 频率 - 开关： | 2MHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 10-MSOP |
| 产品目录页面： | 1093 (CN2011-ZH PDF) |
| 其它名称： | 576-1655-5 MIC4721YMM-ND |
Micrel, Inc.
Efficiency Considerations
Calculating the efficiency is as simple as measuring
power out and dividing it by the power in.
MIC4721
type of material used, approximating core losses
becomes very difficult, so verify inductor temperature
rise.
Efficiency =
P OUT
P IN
× 100
Switching losses occur twice each cycle, when the
switch turns on and when the switch turns off. This is
caused by a non-ideal world where switching transitions
Where input power (P IN ) is:
P IN = V IN × I IN
and output power (P OUT ) is calculated as:
P OUT = V OUT × I OUT
The Efficiency of the MIC2207 is determined by several
factors.
are not instantaneous, and neither are current
transitions. Figure 6 demonstrates (or exaggerates…)
how switching losses due to the transitions dissipate
power in the switch.
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R DSON (Internal P-channel Resistance)
Diode conduction losses
Inductor Conduction losses
Switching losses
R DSON losses are caused by the current flowing through
the high side P-channel MOSFET. The amount of power
loss can be approximated by:
P SW = R DSON × I OUT2 × D
Where D is the duty cycle.
Since the MIC4721 uses an internal P-channel
MOSFET, R DSON losses are inversely proportional to
supply voltage. Higher supply voltage yields a higher
gate to source voltage, reducing the R DSON , thus
reducing the MOSFET conduction losses. A graph
showing typical R DSON vs. input supply voltage can be
found in the typical characteristics section of this
datasheet.
Diode conduction losses occur due to the forward
voltage drop (VF) and the output current. Diode power
losses can be approximated as follows:
P D = V F × I OUT × (1 – D)
For this reason, the low forward voltage drop Schottky
diode is the rectifier of choice. The low forward voltage
drop will help reduce diode conduction losses, and
improve efficiency. Duty cycle, or the ratio of output
voltage to input voltage, determines whether the
dominant factor in conduction losses will be the internal
MOSFET or the Schottky diode. Higher duty cycles
place the power losses on the high side switch, and
lower duty cycles place the majority of power loss on the
Schottky diode.
Inductor conduction losses (PL) can be calculated by
multiplying the DC resistance (DCR) times the square of
the output current:
P L = DCR × I OUT2
Also, be aware that there are additional core losses
associated with switching current in an inductor. Since
most inductor manufacturers do not give data on the
Figure 6. Switching Transition Losses
Normally, when the switch is on, the voltage across the
switch is low (virtually zero) and the current through the
switch is high. This equates to low power dissipation.
When the switch is off, voltage across the switch is high
and the current is zero, again with power dissipation
being low. During the transitions, the voltage across the
switch (VS-D) and the current through the switch (IS-D)
are at midpoint of their excursions and cause the
transition to be the highest instantaneous power point.
During continuous mode, these losses are the highest.
Also, with higher load currents, these losses are higher.
For discontinuous operation, the transition losses only
occur during the “off” transition since the “on” transitions
there is no current flow through the inductor.
Component Selection
Input Capacitor
A 10μF ceramic is recommended on each VIN pin for
bypassing. X5R or X7R dielectrics are recommended for
the input capacitor. Y5V dielectrics lose most of their
capacitance over temperature and voltage and are
therefore not recommended. Also, tantalum and
electrolytic capacitors alone are not recommended
because of their reduced RMS current handling,
reliability, and higher ESR. Smaller case size capacitors
are recommended due to their lower ESL (equivalent
series inductance). Please refer to layout
recommendations for proper layout of the input
capacitors.
May 2007
11
M9999-052907-A
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC4721YMM TR | 功能描述:直流/直流开关调节器 1.5A 2MHz Buck Regulator 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 |
| MIC4721YMMTR | 功能描述:IC REG BUCK ADJ 1.5A 10MSOP RoHS:是 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 |
| MIC4722 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:3mm x 3mm 2.7MHz 3A PWM Buck Regulator |
| MIC4722_10 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:3mm x 3mm 2.7MHz 3A PWM Buck Regulator |
| MIC4722YML | 制造商:Rochester Electronics LLC 功能描述: 制造商:RF Micro Devices Inc 功能描述: |
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