参数资料
| 型号： | MIC2166YMME TR |
| 厂商： | Micrel Inc |
| 文件页数： | 17/28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.
External Schottky Diode (Optional)
An external freewheeling diode can be used to keep the
inductor current flow continuous while both MOSFETs
are turned off.
The diode conducts current during the dead-time. The
dead-time prevents current from flowing unimpeded
through both MOSFETs and is typically 30ns. The diode
conducts twice during each switching cycle. Although the
MIC2166
mostly package inductance and trace inductance. The
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.
C OSS1
average current through this diode is small, the diode
must be able to handle the peak current.
+
L STRAY1
L STRAY2
L
Q1
I D(avg)CM = I OUT × 2 × 30ns × f SW
(25)
C IN
L STRAY3
The reverse voltage requirement of the diode is:
V DC
Sync_buck
Controller
Q2
C OSS2
C OUT
V DIODE(rrm) = V IN
The power dissipated by the Schottky diode is:
–
L STRAY4
P DIODE = I D(avg) × V F
(26)
Figure 5. Output Parasitics
where, V F = forward voltage at the peak diode current.
An external Schottky diode is recommended, even
though the low-side MOSFET contains a parasitic body
diode since the Schottky diode has much less forward
voltage than the body diode. The external diode will
improve efficiency and reduce the high frequency noise.
If the MOSFET body diode is used, 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
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 2 and 10 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.
during the high-side MOSFET turn-on.
L STRAY1
L STRAY2
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
R DS
L STRAY3
R S
recovery mechanism in a Schottky diode causes less
ringing and less power loss.
Snubber Design
C OSS2
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
L STRAY4
Figure 6. Snubber Circuit
C S
September 2010
17
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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