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参数资料
| 型号： | MIC2155YML TR |
| 厂商： | Micrel Inc |
| 文件页数： | 24/35页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 32MLF |
| 特色产品： | MIC2155/6 Buck Control IC |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 550kHz |
| 占空比： | 80% |
| 电源电压： | 4.5 V ~ 14.5 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： | 32-VFQFN 裸露焊盘，32-MLF? |
| 包装： | 标准包装 |
| 产品目录页面： | 1091 (CN2011-ZH PDF) |
| 其它名称： | 576-3527-6 |
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Micrel, Inc.
Inductor Current Sense Components
The RC circuit values that sense current across the
inductor can be calculated once the inductor is selected.
MIC2155/2156
The power dissipated in the input capacitor is:
I
P DISS ( CIN ) = ( CIN ( RMS ) ) 2 × R ESR
The circuit is shown in Figure 20.
0.6
Q2
Output Inductor and
Winding Resistance
0.5
0.4
0.3
0.2
2 Phase
Single Phase
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
0.1
0
Figure 20. Inductor Current Sense
DUTY CYCLE
Figure 21. RMS Input Current vs. Duty Cycle
The inductor has the following values:
MOSFET Selection
= C 1 × R 1
L = 1.0μH, R L = 1.9m ?
Proper sensing of the DC voltage across the inductor
requires the R L /L time constant be equal to the R1×C1
time constant:
L
R L
A good range of values for C1 is 0.1μF to 1μF. For this
example C1 is chosen as 0.22μF. R1 is:
External N-channel logic level power MOSFETs must be
used for the high and low side switches. The MOSFET
gate to source drive voltage of the MIC2155 is regulated
by an internal 5V V DD regulator. Logic level MOSFETs,
whose operation is specified at V GS = 4.5V must be
used. This resistance is used to calculate the losses
during the MOSFET’s conduction time. If operating at
4.5V IN , without connecting V DD to V IN , the gate drive
voltage to the high-side FET could be as low as 3.2V.
MOSFETs with low V GS enhanced gates should be used
in this situation.
It is important to note the on-resistance of a MOSFET
increases at high junction temperature. A 75°C rise in
junction temperature will increase the channel resistance
R 1 =
L
R L × C 1
=
1 μ H
1 . 9 m Ω × 0 . 22 μ F
= 2 . 39 k
of the MOSFET by 40% to 75% of the resistance
specified at 25°C. This change in resistance must be
accounted for when calculating MOSFET power
Input Capacitor Selection
In addition to high-frequency ceramic capacitors, a larger
bulk capacitance, either ceramic or Al. El. should be
used to help attenuate ripple on the input and to supply
current to the input during large output current
transients. The input capacitors must be rated for the
RMS input current of the power supply. RMS input
capacitor current is determined at the maximum output
current. The graph in Figure 21 shows the normalized
RMS input ripple current vs. duty cycle. Data is
normalized to the output current.
For a two-phase converter operating at 17% duty cycle,
the input RMS current is determined from the graph:
I CIN _ RMS ≈ I OUT × 0 . 24 = 7 . 2 A
dissipation.
Total gate charge is the charge required to turn the
MOSFET on and off under specified operating conditions
(V DS and V GS ). The gate charge is supplied by the
MIC2155 gate drive circuit. Gate charge can be a
significant source of power dissipation in the controller
due to the high switching frequencies and generally
large MOSFETs that are driven. At low output load this
power dissipation is noticeable as a reduction in
efficiency.
November 2009
24
M9999-111209-B
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MIC2156 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Two-Phase, Single-Output, PWM Synchronous Buck Control IC |
| MIC2156YML | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:2-Phase, Single Output, PWM Synchronous Buck Control IC |
| MIC2156YML TR | 功能描述:DC/DC 开关控制器 Single Output, PWM Sync 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 |
| MIC2156YML-TR | 功能描述:Buck Regulator Positive Output Step-Down DC-DC Controller IC 32-MLF? (5x5) 制造商:microchip technology 系列:- 包装:剪切带（CT） 零件状态:过期 输出类型:晶体管驱动器 功能:降压 输出配置:正 拓扑:降压 输出数:2 输出阶段:2 电压 - 电源（Vcc/Vdd）:4.5 V ~ 14.5 V 频率 - 开关:300kHz 占空比（最大）:0.8 同步整流器:是 时钟同步:是 串行接口:- 控制特性:限流，使能，电源良好，软启动 工作温度:-40°C ~ 125°C （TJ） 封装/外壳:32-VFQFN 裸露焊盘，32-MLF? 供应商器件封装:32-MLF?（5x5） 标准包装:1 |
| MIC2159 | 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:SYNCHRONOUS-itty⑩ Step-Down Converter IC |
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