参数资料
| 型号： | MIC2174-1YMM TR |
| 厂商： | Micrel Inc |
| 文件页数： | 17/27页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 10-MSOP |
| 产品培训模块： | MIC2124 Synchronous Current Mode DC-DC Buck Controller |
| 标准包装： | 2,500 |
| 系列： | Hyper Speed Control™ |
| PWM 型： | 混合物 |
| 输出数： | 1 |
| 频率 - 最大： | 375kHz |
| 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.
MIC2174/MIC2174C
I D(avg) = I OUT × 2 × 30ns × f SW
(26)
C OSS1
The reverse voltage requirement of the diode is:
+
L STRAY1
L STRAY2
L
Q1
V DIODE(rrm) = V HSD
The power dissipated by the Schottky diode is:
C IN
L STRAY3
P DIODE = I D(avg) × V F
(27)
V DC
Sync_buck
Controller
Q2
C OSS2
C OUT
L STRAY4
where, V F = forward voltage at the peak diode current.
The external Schottky diode is not necessary for the
circuit operation since the low-side MOSFET contains a
parasitic body diode. The external diode will improve
efficiency and decrease the high frequency noise. If the
MOSFET body diode is used, then it must be rated to
handle the peak and average current. The body diode
has a relatively slow reverse recovery time and a
relatively high forward voltage drop. The power lost in
the diode is proportional to the forward voltage drop of
the diode. As the high-side MOSFET starts to turn on,
the body diode becomes a short circuit for the reverse
recovery period, dissipating additional power. The diode
recovery and the circuit inductance will cause ringing
during the high-side MOSFET turn-on.
An external Schottky diode conducts at a lower forward
voltage preventing the body diode in the MOSFET from
turning on. The lower forward voltage drop dissipates
less power than the body diode. The lack of a reverse
recovery mechanism in a Schottky diode causes less
–
Figure 5. Output Parasitics
One method of reducing the ringing is to use a resistor
and capacitor to lower the Q of the resonant circuit, as
shown in Figure 6. Capacitor C S is used to block DC and
minimize the power dissipation in the resistor. This
capacitor value should be between two and ten times the
parasitic capacitance of the MOSFET C OSS . A capacitor
that is too small will have high impedance and prevent
the resistor from damping the ringing. A capacitor that is
too large causes unnecessary power dissipation in the
resistor, which lowers efficiency.
ringing and less power loss. Depending upon the circuit
components and operating conditions, an external
Schottky diode will give a 1/2% to 1% improvement in
L STRAY1
R DS
L STRAY2
efficiency.
Snubber Design
A snubber is used to damp out high frequency ringing
caused by parasitic inductance and capacitance in the
buck converter circuit. Figure 5 shows a simplified
schematic of the buck converter. Stray capacitance
consists mostly of the two MOSFETs’ output
capacitance (C OSS ). The stray inductance consists
mostly package inductance and trace inductance. The
L STRAY3
C OSS2
L STRAY4
R S
C S
arrows show the resonant current path when the high
side MOSFET turns on. This ringing causes stress on
the semiconductors in the circuit as well as increased
EMI.
Figure 6. Snubber Circuit
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
capacitance. Placing the snubber too far from the FET or
using trace that is too long or thin will add inductance to
the snubber and diminishes its effectiveness.
September 2010
17
M9999-091310-C
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2174C | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Synchronous Buck Controller Featuring Adaptive On-Time Control 40V Input, 300kHz |
| MIC2174C-1YMM | 功能描述:DC/DC 开关控制器 Low Cost 40V 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 |
| MIC2174C-1YMM TR | 功能描述:DC/DC 开关控制器 Low Cost 40V 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 |
| MIC2176-1 | 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 |
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