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| 型号： | IR3811MTRPBF |
| 厂商： | International Rectifier |
| 文件页数： | 10/21页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 7A 15QFN |
| 产品培训模块： | SupIRBuck™ Integrated Point-of-Load Regulators SupIRBuck? Family and POL Design Tools Overview |
| 产品变化通告： | (EP) Parts Discontinuation 25/May/2012 |
| 标准包装： | 1 |
| 系列： | SupIRBuck™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 12 V |
| 输入电压： | 2.5 V ~ 21 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 600kHz |
| 电流 - 输出： | 7A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 15-PowerVQFN |
| 包装： | 标准包装 |
| 供应商设备封装： | PQFN（5x6） |
| 产品目录页面： | 1384 (CN2011-ZH PDF) |
| 其它名称： | IR3811MTRPBFDKR |
PD-60334
IR3811MPbF
Over-Current Protection
The over current protection is performed by
sensing current through the R DS(on) of the low-
side MOSFET. This method enhances the
converter’s efficiency and reduces cost by
eliminating a current sense resistor. As shown in
figure 7, an external resistor (R SET ) is connected
between OCSet pin and the inductor point which
sets the current limit set point.
The internal current source develops a voltage
across R SET . When the low side MOSFET is
turned on, the inductor current flows through the
Q2 and results a voltage which is given by:
Fig. 8: 3uA current source for discharging
soft-start capacitor during hiccup
The OCP circuit starts sampling current when the
V OCSet = (I OCSet ? R OCSet ) ? (R DS(on) ? I L )
--( 2 )
low gate drive is about 3V. The OCSet pin is
internally clamped about 1.5V during on time of
high side gate to prevent false trigging, figure 9
shows the OCSet pin during one switching cycle.
As shown, there is about 150ns delay to mask
the dead time. Since this node contains switching
noises, this delay also functions as a filter.
Deadtime
Fig. 7: Connection of over current sensing resistor
The critical inductor current can be calculated by
setting:
I OCSet *R OCSet
Blanking time
Clamp voltage
V OCSet = (I OCSet ? R OCSet ) ? (R DS(on) ? I L ) = 0
Fig. 9: OCset pin during normal condition
I SET = I L ( critical )
=
R OCSet ? I OCSet
R DS ( on )
--( 3 )
Ch1: Inductor point, Ch3:OCSet
An over current is detected if the OCSet pin goes
below ground. This trips the OCP comparator
and cycles the soft start function in hiccup mode.
The hiccup is performed by charging and
discharging the soft-start capacitor in a certain
slope rate. As shown in figure 8 a 3uA current
source is used to discharge the soft-start
capacitor.
The OCP comparator resets after every soft start
cycle. The converter stays in this mode until the
overload or short circuit is removed. The
converter will automatically recover.
10/04/08
The value of R SET should be checked in an actual
circuit to ensure that the over current protection
circuit activates as expected. The IR3811 current
limit is designed primarily as disaster preventing,
and doesn't operate as a precision current
regulator.
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| IR3812MPBF | 制造商:International Rectifier 功能描述: |
| IR3812MPBF_08 | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGHLY INTEGRATED 4A WIDE-INPUT VOLTAGE, SYNCHRONOUS BUCK REGULATOR |
| IR3812MTR1PBF | 功能描述:直流/直流开关调节器 4A SupIRBuck Reg 600kHz, 2.5-21V in RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| IR3812MTRPBF | 功能描述:直流/直流开关调节器 4A SupIRBuck Reg 600kHz, 2.5-21V in RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| IR3820AMPBF | 制造商:International Rectifier 功能描述:Conv DC-DC Single Step Down 2.5V to 21V 15-Pin Power QFN EP |
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