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参数资料
| 型号： | LTC3411AEMS#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/22页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 10MSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 5 V |
| 输入电压： | 2.5 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 2.5MHz |
| 电流 - 输出： | 1.25A |
| 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： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-MSOP |
LTC3411A
APPLICATIONS INFORMATION
V OUT ≈ 0.8V ? 1 +
0V
In most applications, the input capacitor is merely required
to supply high frequency bypassing, since the impedance
to the supply is very low. A 10μF ceramic capacitor is
usually enough for these conditions.
Setting the Output Voltage
The LTC3411A develops a 0.8V reference voltage between
the feedback pin, V FB , and the signal ground as shown in
Figure 4. The output voltage is set by a resistive divider
according to the following formula:
? R2 ?
?
? R1 ?
Keeping the current small (<5μA) in these resistors maxi-
mizes efficiency, but making them too small may allow
stray capacitance to cause noise problems and reduce the
phase margin of the error amp loop.
To improve the frequency response, a feed-forward capaci-
tor C F may also be used. Great care should be taken to
route the V FB line away from noise sources, such as the
inductor or the SW line.
Shutdown and Soft-Start
The SHDN/R T pin is a dual purpose pin that sets the oscil-
lator frequency and provides a means to shut down the
LTC3411A. This pin can be interfaced with control logic in
several ways, as shown in Figure 2 and Figure 3. In both
configurations, Run = “0” shuts down the LTC3411A and
Run = “1” activates the LTC3411A.
Care must be taken when using Figure 3 to shut down
the part in force continuous mode. The pull up resistor
should be as small as the application would allow and
the pull down transistor should be as small as possible
to minimize its parasitic drain capacitance. If possible,
always shut down the part while in pulse skipping mode
or Burst Mode operation. Figure 4 shows an example
SHDN/R T
R T
RUN
3411A F02
of how to switch from force continuous mode to pulse
skipping mode when RUN goes low. The parasitic drain
capacitance of a large transistor coupled with a large pull
up resistor results in large RC constants. As RUN goes
low, the transistor drain charges up slowly, gradually de-
creasing the oscillator frequency of the part. This leads to
large inductor current ripples translating into large output
voltage ripples. In some cases, the output voltage could
rise up to dangerous levels.
When activating the LTC3411A, an internal soft-start slowly
ramps the output voltage up until regulation. Soft-start
prevents surge currents from V IN by gradually ramping
the output voltage up during start-up. The output will ramp
from zero to full scale over a time period of approximately
0.7ms. This prevents the LTC3411A from having to quickly
charge the output capacitor and thus supplying an exces-
sive amount of instantaneous current.
The LTC3411A can start into a back-biased output in forced
continuous operation. When the output is pre-biased at
either a higher or lower value than the regulated output
voltage, the LTC3411A will sink or source current as needed
to bring the output back into regulation. However, during
soft-start the regulator will always start in pulse skipping
mode ignoring the mode selected with the SYNC/MODE
SHDN/R T SV IN
R T 100k
RUN
3411A F03
Figure 3. SHDN/R T Pin Activated with a Switch
SHDN/R T SV IN
R T 1M
3V
OFF ON
100k
SYNC/MODE
100k
3411A F04
Figure 2. SHDN/R T Pin Activated with a Logic Input
Figure 4. Automatic Mode Change Circuit
3411afc
For more information www.linear.com/LTC3411A
13
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| LTC3411AIDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC3411AIDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC3411AIDD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3411AIDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.25A, 4MHz, Synchronous Step-Down DC/DC Converter |
| LTC3411AIMS#PBF | 功能描述:IC REG BUCK SYNC ADJ 10MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
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