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参数资料
| 型号： | IR3638STRPBF |
| 厂商： | International Rectifier |
| 文件页数： | 8/15页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 14-SOIC |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 95% |
| 电源电压： | 5 V ~ 13.2 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： | 0°C ~ 125°C |
| 封装/外壳： | 14-SOIC（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 产品目录页面： | 1384 (CN2011-ZH PDF) |
| 其它名称： | IR3638STRPBFDKR |
IR3638SP b F
Soft-Start
The IR3638 has programmable soft-start to
control the output voltage rise and limit the inrush
22uA
3V
current during start-up.
To ensure correct start-up, the soft-start
SS/SD
sequence initiates when Vcc and Enable rise
64uA
above their threshold and generate the Power On
Ready (POR) signal. The soft-start function
POR
operates by sourcing current to charge an
external capacitor to about 3V.
Comp
25K
Error Amp
Initially, the soft-start function clamps the output
Vp
of error amplifier by injecting a current (64uA)
into the Fb pin and generates a voltage about
Fb
25K
1.6V (64ux25K) across the negative input of error
amplifier (see figure 6).
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
Fig. 6: Soft-Start circuit for IR3638
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 negative input of the error amplifier
is approximately 0.8V (32uAx25K).
Output of UVLO
As soon as the Fb reaches the Vp voltage, the
POR
3V
output of error amplifier will start increasing and
generating the first PWM signal. As the soft-start
? 2V
capacitor voltage continues to ramp up, the
current flowing into the Fb pin will keep
decreasing.
The feedback voltage increases linearly as the
soft start voltage ramps up. When soft-start
Soft-Start
Voltage
Current flowing
into Fb pin
0V
64uA
0uA
? 1V
voltage is around 2V the output voltage is
reached the steady state and the injected current
is zero.
Voltage at negative input ? 1.6V
of Error Amp
0.8V
Figure 7 shows the theoretical operational
waveforms during soft-start.
Vp=0.8V
The output voltage start-up time is the time
period when soft-start capacitor voltage
Voltage at Fb pin
0V
increases from 1V to 2V.
The start-up time will be dependent on the size of
T start
the external soft-start capacitor and can be
estimate by:
22 μ A ? = 2 V ? 1 V
C ss
Fig. 7: Theoretical operation waveforms
during soft-start
For a given start-up time, the soft-start capacitor
(nF) can be estimated as:
C SS ? 22 μ A * T start ( ms )
--( 1 )
3/19/07
8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| IR3640MPBF | 功能描述:IC REG CTRLR BUCK PWM VM 20-MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| IR3640MTRPBF | 功能描述:开关变换器、稳压器与控制器 HI FREQ SYNC PWM 4.5 to 5.5V 1.5MHz RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| IR3651 | 制造商:IRF 制造商全称:International Rectifier 功能描述: |
| IR3651SPBF | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| IR3651STRPBF | 功能描述:电压模式 PWM 控制器 High Volt Sych PWM 100V 400Mhz 1.25 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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