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参数资料
| 型号： | IR3628MPBF |
| 厂商： | International Rectifier |
| 文件页数： | 9/22页 |
| 文件大小： | 0K |
| 描述： | IC CTLR PWM BUCK SYNC 12-MLPD |
| 标准包装： | 122 |
| 应用： | 控制器，DDR |
| 输入电压： | 4.5 V ~ 14 V |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 9.94 V |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 12-VFDFN 裸露焊盘 |
| 供应商设备封装： | 12-MLPD |
| 包装： | 管件 |
IR3628MP b F
Soft-Start
The IR3628 has programmable soft-start to
control the output voltage rise and limit the inrush
current during start-up.
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
20uA
SS/SD
POR
3V
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
0.96V (40ux24K) across the negative input of
Comp
0.6V
Fb
24K
24K
Error Amp
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
Fig. 5: Soft-Start circuit for IR3628
is approximately 0.6V.
The output of error amplifier will start increasing
and generating the first PWM signal. As the soft-
start capacitor voltage continues to go up, the
Output of UVLO
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 is
Soft-Start
Voltage
Current flowing
into Fb pin
0V
40uA
0uA
? 1V
reached the steady state and the injected current
is zero.
Figure 6 shows the theoretical operational
waveforms during soft-start.
The output voltage start-up time is the time
Voltage at negative input ? 0.96V
of Error Amp
0.6V
0.6V
period when soft-start capacitor voltage
increases from 1V to 2V.
The start-up time will be dependent on the size of
the external soft-start capacitor and can be
Voltage at Fb pin
0V
estimate 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
(nF) can be estimated as:
C SS ? 20 μ A * T start ( ms )
08/10/2007
--( 1 )
9
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| IR3628MTRPBF | 功能描述:电压模式 PWM 控制器 HI FREQ SYNC PWM 600kHz 5 or 12V 0.6 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| IR3629 | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER WITH POWER GOOD OUTPUT |
| IR3629A | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER WITH POWER GOOD OUTPUT |
| IR3629AMPBF | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGH FREQUENCY SYNCHRONOUS PWM BUCK CONTROLLER WITH POWER GOOD OUTPUT |
| IR3629AMTRPBF | 功能描述:电压模式 PWM 控制器 HI FREQ SYNC PWM 600kHz 5 or 12V 0.6 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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