参数资料
| 型号： | MIC2166YMME TR |
| 厂商： | Micrel Inc |
| 文件页数： | 18/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM HYBRID 10TSOP |
| 标准包装： | 2,500 |
| 系列： | Hyper Speed Control™ |
| PWM 型： | 混合物 |
| 输出数： | 1 |
| 频率 - 最大： | 750kHz |
| 占空比： | 82% |
| 电源电压： | 4.5 V ~ 28 V |
| 降压： | 无 |
| 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）裸露焊盘 |
| 包装： | 带卷 (TR) |
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Micrel, Inc.
MIC2166
( f ) ? 1
The snubber components should be placed as close as
possible to the low-side MOSFET and/or external
Schottky diode since it contributes to most of the stray
C P =
C S
' 2
(29)
capacitance. Placing the snubber too far from the
MOSFET or using a trace that is too long or thin will add
inductance to the snubber and diminishes its
L P is solved by re-arranging the equation for f 1 :
( 2 π )
effectiveness.
A proper snubber design requires that the parasitic
inductance and capacitance be known. A method of
determining these values and calculating the damping
L P =
2
1
× C P × ( f 1 ) 2
(30)
resistor value is outlined below:
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 .
Step 3: Calculate the damping resistor.
Critical damping occurs at Q = 1:
2. Add a capacitor C S (such as 2 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
Q = R S ×
C P
L P
= 1
(31)
(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 .
3. Add a resistor R S in series with C S to generate
critical damping.
Solving for R S :
Step 1: First measure the ringing frequency on the
switch node voltage when the high-side MOSFET turns
R S =
L P
C p
(32)
on. This ringing is characterized by the equation:
Figure 6 shows the snubber in the circuit and the
f 1 =
1
2 π L P × C P
(27)
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 the equation below:
f 2 =
(28)
f ' = 1
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 2 times the C OSS of Q2. Measure the
frequency of the switch node ringing, f 2 :
1
2 π Lp × ( Cs + Cp )
Define f’ as:
f
f 2
Combining the equations for f 1 , f 2 and f’ to derive C P , the
parasitic capacitance:
P SNUBBER = f SW × C S × V IN 2 (33)
Ripple Injection
The V FB ripple required for proper operation of the
MIC2166 g m 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, the output voltage ripple is
only 10mV to 20mV, and the V FB ripple is less than
20mV. If the V FB ripple is so small that the g m amplifier
and error comparator cannot sense it, the MIC2166 will
lose control and the output voltage is not regulated. In
order to have some amount of V FB ripple, a ripple
injection method is applied for low output voltage ripple
applications.
September 2010
18
M9999-092410-C
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| MIC2168 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:1MHz PWM Synchronous Buck Control IC |
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| MIC2168ABMM | 功能描述:IC REG CTRLR BUCK PWM VM 10-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| MIC2168ABMM TR | 功能描述:IC REG CTRLR BUCK PWM VM 10-MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
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