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| 型号： | MCP1650ST-E/MS |
| 厂商： | Microchip Technology |
| 文件页数： | 17/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK PWM 8MSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 850kHz |
| 占空比： | 80% |
| 电源电压： | 2.7 V ~ 5.5 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 是 |
| 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： | 8-TSSOP，8-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
| 配用： | MCP1650EV-ND - BOARD EVAL FOR MCP1650,51,52,53 MCP1650DM-LED1-ND - BOARD DEMO FOR MCP165X |
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MCP1650/51/52/53
5.2
Design Considerations
5.2.1.1
Calculations
When developing switching power converter circuits,
there are numerous things to consider and the
MCP1650/51/52/53 family is no exception. The gated
oscillator architecture does provide a simple control
approach so that stabilizing the regulator output is an
easier task than that of a fixed-frequency regulator.
The MCP1650/51/52/53 controller utilizes an external
switch and diode allowing for a very wide range of
conversion (high voltage gain and/or high current gain).
There are practical, as well as power-conversion,
topology limitations. The MCP1650/51/52/53 gated
oscillator hysteretic mode converter has similar
limitations, as do fixed-frequency boost converters.
P OUT = V O UT × I OU T
Where:
P OUT = 12V X 100 mA
P OUT = 1.2 Watts
P IN = P OU T ? ( Efficiency )
Where:
P IN = 1.2W/80%
(80% is a good efficiency estimate)
P IN = 1.5 Watts
For gated oscillator hysteretic designs, the switching
5.2.1
DESIGN EXAMPLE
Input Voltage = 2.8V to 4.2V
frequency is not constant and will gate several pulses
to raise the output voltage. Once the upper hysteresis
threshold is reached, the gated pulses stop and the
V O UT = ? ------------- ? × V IN
R TO P = R BO T × ? ? ? ? ? ? – 1 ? ?
V OU T
V OUTMAX = ? ? ? ? × 2.8
----------------
V OU TMAX = ? ------------------- ? × 3.8
Output Voltage = 12V
Output Current = 100 mA
Oscillator Frequency = 750 kHz
Duty cycle = 80% for V IN < 3.8V
Duty cycle = 56% for V IN > 3.8V
Setting the output voltage:
-------------
V FB
Where:
R TOP = Top Resistor Value
R BOT = Bottom Resistor Value
By adjusting the external resistor divider, the output
voltage of the boost converter can be set to the desired
value. Due to the RC delay caused by the resistor
divider and the device input capacitance, resistor
values greater than 100 k ? are not recommended. The
feedback voltage is typically 1.22V.
For this example:
R BOT = 10 k ?
V OUT = 12V
V FB = 1.22V
R TOP = 88.4 k ?
90.9 K ? was selected as the closest standard value.
? 2004 Microchip Technology Inc.
output will coast down at a rate determined by the out-
put capacitor and the load. Using the gated oscillator
switching frequency and duty cycle, it is possible to
determine what the maximum boost ratio is for
continuous inductor current operation.
1
? 1 – D ?
This relationship assumes that the output load current
is significant and the boost converter is operating in
Continuous Inductor Current mode. If the load is very
light or a small boost inductance is used, higher boost
ratio’s can be achieved.
Calculate at minimum V IN :
1
1 – 0.8
The ideal maximum output voltage is 14V. The actual
measured result will be less due to the forward voltage
drop in the boost diode, as well as other circuit losses.
For applications where the input voltage is above and
below 3.8V, another point must be checked to deter-
mine the maximum boost ratio. At 3.8V, the duty cycle
changes from 80% to 56% to minimize the peak current
in the inductor.
1
? 1 – 0.56 ?
For this case, V OUTMAX = 8.63V less than the required
12V output specified. The size of the inductor has to
decrease in order to operate the boost regulator in
Discontinuous Inductor Current mode.
DS21876A-page 17
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相关代理商/技术参数 |
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|---|---|
| MCP1651 | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:750 kHz Boost Controller |
| MCP1651R-E/MS | 功能描述:热插拔功率分布 w/Lbat Ind UVLO 2V RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MCP1651REMS | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:750 kHz Boost Controller |
| MCP1651REUN | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:750 kHz Boost Controller |
| MCP1651RT-E/MS | 功能描述:热插拔功率分布 w/Lbat Ind UVLO 2V RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
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