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参数资料
| 型号： | MIC2174C-1YMM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 18/27页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 10-MSOP |
| 标准包装： | 2,500 |
| 系列： | Hyper Speed Control™ |
| PWM 型： | 混合物 |
| 输出数： | 1 |
| 频率 - 最大： | 338kHz |
| 占空比： | 87% |
| 电源电压： | 3 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： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
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Micrel, Inc.
A proper snubber design requires the parasitic
inductance and capacitance be known. A method of
determining these values and calculating the damping
resistor value is outlined below.
MIC2174/MIC2174C
Step 3: Calculate the damping resistor.
Critical damping occurs at Q = 1:
1. Measure the ringing frequency at the switch node
which is determined by parasitic L P and C P . Define
this frequency as f 1 .
2. Add a capacitor C S (such as two times as big as the
C OSS of the FET) from the switch node-to-ground
and measure the new ringing frequency. Define this
new (lower) frequency as f 2 . L P and C P can now be
solved using the values of f 1 , f 2 and C S .
Q = R S ×
Solving for R S
L P
R S =
C p
C P
L P
= 1
(32)
(33)
3. Add a resistor R S in series with C S to generate
critical damping.
Step 1: First measure the ringing frequency on the
switch node voltage when the high-side MOSFET turns
on. This ringing is characterized by the equation:
Figure 6 shows the snubber in the circuit and the
damped switch node waveform. The snubber capacitor,
C S , is charged and discharged each switching cycle. The
energy stored in C S is dissipated by the snubber resistor,
R S , two times per switching period. This power is
calculated in Equation 34:
f 1 =
1
2 π L P × C P
(28)
P SNUBBER = f SW × C S × V IN 2
(34)
Ripple Injection
where C P and L P are the parasitic capacitance and
inductance.
Step 2: Add a capacitor, C S , in parallel with the
synchronous MOSFET, Q2. The capacitor value should
be approximately two times the C OSS of Q2. Measure the
frequency of the switch node ringing, f 2 :
The V FB ripple required for proper operation of the
MIC2174/MIC2174C gm amplifier and error comparator
is 20mV to 100mV. However, the output voltage ripple is
generally designed as 1% to 2% of the output voltage.
For a low output voltage, such as a 1V output, the output
voltage ripple is only 10mV to 20mV, and the FB voltage
ripple is less than 20mV. If the FB voltage ripple is so
Define f’ as:
f 2 =
1
2 π Lp × ( Cs + Cp )
(29)
small that the gm amplifier and error comparator can’t
sense it, then the MIC2174/MIC2174C will lose control
and the output voltage will not be regulated. In order to
have some amount of V FB voltage ripple, a ripple
injection method is applied for low output voltage ripple
applications.
The applications are divided into three situations
f ' = 1
f
f 2
Combining the equations for f 1 , f 2 and f’ to derive C P , the
parasitic capacitance:
according to the amount of the FB voltage ripple:
1. Enough ripple at the FB voltage due to the large
ESR of the output capacitors.
C P =
C S
( f ) ' 2 ? 1
(30)
As shown in Figure 7a, the converter is stable without
any ripple injection. The FB voltage ripple is:
L P is solved by re-arranging the equation for f 1 :
Δ V FB(pp) =
R2
R1 + R2
× ESR C OUT × Δ I L (pp)
(35)
L P =
September 2010
1
( 2 π ) 2 × C P × f( 1 ) 2
(31)
18
where Δ I L(pp) is the peak-to-peak value of the inductor
current ripple.
M9999-091310-C
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2176-1 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Wide Input Voltage, Synchronous Buck Controllers Featuring Adaptive On-Time Control |
| MIC2176-1YMM | 功能描述:DC/DC 开关控制器 76V Synchronous Buck Controller 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 |
| MIC2176-1YMM TR | 功能描述:DC/DC 开关控制器 76V Synchronous Buck Controller 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 |
| MIC2176-2 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Wide Input Voltage, Synchronous Buck Controllers Featuring Adaptive On-Time Control |
| MIC2176-2YMM | 功能描述:DC/DC 开关控制器 76V Synchronous Buck Controller 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 |
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