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| 型号： | MIC2131-4YTSE |
| 厂商： | Micrel Inc |
| 文件页数： | 14/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 16TSSOP |
| 标准包装： | 94 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 80% |
| 电源电压： | 8 V ~ 40 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 ~ 125°C |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1091 (CN2011-ZH PDF) |
| 其它名称： | 576-3099-5 |
V OUTPK ? PK ≈ I RIPPLE ? ESR +
1 4 4 2 43
? ?
? ? ? 1 ?
I O ? F SWITCH
V IN ? Efficiency
( 1 ? D ) V OUT
Micrel, Inc.
Application Information
Passive Component Selection Guide
Transition losses in the power MOSFETs are not defined
by inductor value. However, the inductor value is
responsible for the ripple current which causes some of
the resistive losses. These losses are proportional to
I RIPPLE2 . Minimizing inductor ripple current therefore
reduces resistive losses and can be achieved by
choosing a larger value inductor. This will generally
improve efficiency by reducing the RMS current flowing
in all of the power components. The actual value of
inductance is really defined by space limitations, RMS
rating (I RMS ) and saturation current (I SAT ) of available
inductors. If we look at the newer flat wire inductors,
these have higher saturation current ratings than the
RMS current rating for lower values and as inductance
value increases, these figures get closer in value. This
mirrors what happens in the converter with I SAT
analogous to the maximum peak switch current and I RMS
analogous to output current. As inductance increases, so
I SWITCHpk tends towards I OUT . This is a characteristic that
makes these types of inductor optimal for use in high
power buck converters such as MIC2130/31.
To determine the I SAT and I RMS rating of the inductor, we
should start with a nominal value of ripple current. This
should typically be no more than I OUT(max) /2 to minimize
MOSFET losses due to ripple current mentioned earlier.
Therefore:
V O ? V O ?
L MIN ~ 2
? ?
IL RMS > 1.04 x I OUT(max)
IL SAT > 1.25 x I OUT(max)
Any value chosen above L MIN will ensure these ratings
are not exceeded.
In considering the actual value to choose, we need to
look at the effect of ripple on the other components in
the circuit. The chosen inductor value will have a ripple
current of:
I RIPPLE ~ ?
F SWITCH L
This value should ideally be kept to a minimum, within
the cost and size constraints of the design, to reduce
unnecessary heat dissipation.
Output Capacitor Selection
The output capacitor (C OUT ) will have the full inductor
ripple current IL RMS flowing through it. This creates the
output switching noise which consists of two main
components:
MIC2130/1
I RIPPLE ? T ON
3
1 4 4 2 4 4 2 ? C
ESR
Noise Capacitor
Noise
If therefore, the need is for low output voltage noise
(e.g., in low output voltage converters), V OUT ripple can
be directly reduced by increasing inductor value, Output
capacitor value or reducing ESR.
For tantalum capacitors, ESR is typically >40m ? which
usually makes loop stabilization easier by utilizing a
pole-zero (type II) compensator.
Due to the many advantages of multi-layer ceramic
capacitors, among them, cost, size, ripple rating and
ESR, it can be useful to use these in many cases.
However, one disadvantage is the CV product. This is
lower than tantalum. A mixture of one tantalum and one
ceramic can be a good compromise which can still utilize
the simple type II compensator.
With ceramic output capacitors only, a double-pole,
double-zero (type III) compensator is required to ensure
system stability. Loop compensation is described in
more detail later in the data sheet.
Ensure the RMS ripple current rating of the capacitor is
above I RIPPLE ? 0.6 to improve reliability.
Input Capacitor Selection
The input filter needs to supply the load current when the
high-FET is on and should to limit the ripple to the desire
value. The C IN ripple rating for a converter is typically
I OUT /2 under worst case duty cycle conditions of 50%.
IRMS CIN = I OUT × D × ( 1 ? D )
Where D = V OUT /(V IN xeff)
It is however, also important to closely decouple the
Power MOSFETs with 2 x 10μF Ceramic capacitors to
reduce ringing and prevent noise related issues from
causing problems in the layout of the regulator. The
ripple rating of C IN may therefore be satisfied by these
decoupling capacitors as they allow the use of perhaps
one more ceramic or tantalum input capacitor at the
input voltage node to decouple input noise and localize
high di/dt signals to the regulator input.
Power MOSFET Selection
The MIC2130/31 drives N-channel MOSFETs in both the
high-side and low-side positions. This is because the
switching speed for a given RDS ON in the N-Channel
device is superior to the P-Channel device.
There are different criteria for choosing the high- and
low-side MOSFETs and these differences are more
significant at lower duty cycles such as 12V to 1.8V
conversion. In such an application, the high-side
MOSFET is required to switch as quickly as possible to
minimize transition losses (power dissipated during rise
April 2008
14
M9999-042108-C
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相关代理商/技术参数 |
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|---|---|
| MIC2131-4YTSE TR | 功能描述:DC/DC 开关控制器 High Voltage 150KHz Synchronous Buck Control IC 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 |
| MIC2141 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Micropower Boost Converter Preliminary Information |
| MIC2141_06 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Micropower Boost Converter |
| MIC2141BM5 | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| MIC2141-BM5 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Micropower Boost Converter Preliminary Information |
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