参数资料
型号: IR3811MTRPBF
厂商: International Rectifier
文件页数: 9/21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:
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
Soft-Start
The IR3811 has programmable soft-start to
control the output voltage rise and limit the inrush
current during start-up.
20uA
3V
To ensure correct start-up, the soft-start
sequence initiates when Vcc and Vc rise above
their threshold and generate the Power On
Ready (POR) signal. The soft-start function
SS/SD
POR
40uA
operates by sourcing current to charge an
external capacitor to about 3V.
Initially, the soft-start function clamps the output
of error amplifier by injecting a current (40uA)
into the Fb pin and generates a voltage about
Comp
0.6V
Fb
24K
24K
Error Amp
0.96V (40ux24K) across the negative input of
error amplifier (see figure 5).
The magnitude of the injected current is inversely
proportional to the voltage at the soft-start pin. As
the soft-start voltage ramps up, the injected
current decreases linearly and so does the
voltage at negative input of error amplifier.
When the soft-start capacitor is around 1V, the
voltage at the positive input of the error amplifier
is approximately 0.6V.
Fig. 5: Soft-Start circuit for IR3811
Output of UVLO
The output of error amplifier will start increasing
and generating the first PWM signal. As the soft-
start capacitor voltage continues to rise up, the
POR
3V
? 2V
current flowing into the Fb pin will keep
decreasing.
The feedback voltage increases linearly as the
soft start voltage ramps up. When soft-start
voltage is around 2V, the output voltage reaches
Soft-Start
Voltage
Current flowing
into Fb pin
0V
40uA
0uA
? 1V
the steady state and the injected current is zero .
Figure 6 shows the theoretical operating
waveforms during soft-start.
The output voltage start-up time is the time
period when soft-start capacitor voltage
Voltage at negative input ? 0.96V
of Error Amp
0.6V
0.6V
increases from 1V to 2V.
The start-up time will be dependent on the size of
Voltage at Fb pin
0V
the external soft-start capacitor and can be
estimated by:
Fig. 6: Theoretical operation waveforms
20 μ A ?
T start
C ss
= 2 V ? 1 V
during soft-start
For a given start-up time, the soft-start capacitor
can be estimated as:
10/04/08
C SS ? 20 μ A * T start ( ms )
--( 1 )
9
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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