参数资料
| 型号： | LTC3411AIMS#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 9/22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
OPERATION
The LTC3411A uses a constant frequency, current mode
architecture. The operating frequency is determined by the
value of the R T resistor or can be synchronized to an external
oscillator. To suit a variety of applications, the selectable
MODE pin allows the user to trade-off noise for efficiency.
The output voltage is set by an external divider returned
to the V FB pin. An error amplifier compares the divided
output voltage with the reference voltage of 0.8V and ad-
justs the peak inductor current accordingly. Overvoltage
and undervoltage comparators will pull the PGOOD output
low if the output voltage is not within ±7% of its regulated
value. A tripping delay of 40μs and untripping delay of
105μs ensures PGOOD will not glitch due to transient
spikes on V OUT .
Main Control Loop
During normal operation, the top power switch (P-channel
MOSFET) is turned on at the beginning of a clock cycle.
Current flows through this switch into the inductor and
the load, increasing until the peak inductor current reaches
the limit set by the voltage on the I TH pin. Then the top
switch is turned off, the bottom switch is turned on, and
the energy stored in the inductor forces the current to flow
through the bottom switch and the inductor, out into the
load until the next clock cycle.
The peak inductor current is controlled by the voltage
on the I TH pin, which is the output of the error amplifier.
The output is developed by the error amplifier comparing
the feedback voltage, V FB , to the 0.8V reference voltage.
When the load current increases, the output voltage and
V FB decrease slightly. This decrease in V FB causes the er-
ror amplifier to increase the I TH voltage until the average
inductor current matches the new load current.
The main control loop is shut down by pulling the SHDN/R T
pin to SV IN , resetting the internal soft-start. Re-enabling the
main control loop by releasing the SHDN/R T pin activates the
internal soft-start, which slowly ramps the output voltage
over approximately 0.8ms until it reaches regulation.
Low Current Operation
Three modes are available to control the operation of the
LTC3411A at low currents. All three modes automatically
switch from continuous operation to the selected mode
when the load current is low.
To optimize efficiency, the Burst Mode operation can be
selected. When the load is relatively light, the LTC3411A
automatically switches into Burst Mode operation in which
the PMOS switch operates intermittently based on load
demand. By running cycles periodically, the switching
losses which are dominated by the gate charge losses
of the power MOSFETs are minimized. The main control
loop is interrupted when the output voltage reaches the
desired regulated value. The burst comparator trips when
I TH is below approximately 0.5V, shutting off the switch
and reducing the power. The output capacitor and the
inductor supply the power to the load until I TH rises above
approximately 0.5V, turning on the switch and the main
control loop which starts another cycle.
For lower output voltage ripple at low currents, pulse
skipping mode can be used. In this mode, the LTC3411A
continues to switch at a constant frequency down to
very low currents, where it will eventually begin skipping
pulses.
Finally, in forced continuous mode, the inductor current
is constantly cycled which creates a fixed output voltage
ripple at all output current levels. This feature is desirable
in telecommunications since the noise is at a constant fre-
quency and is thus, easy to filter out. Another advantage of
this mode is that the regulator is capable of both sourcing
current into a load and sinking current from the output.
Dropout Operation
When the input supply voltage decreases toward the
output voltage, the duty cycle increases to 100% which
is the dropout condition. In dropout, the PMOS switch
is turned on continuously with the output voltage being
equal to the input voltage minus the voltage drop across
the internal P-channel MOSFET and the inductor.
Low Supply Operation
The LTC3411A incorporates an undervoltage lockout circuit
which shuts down the part when the input voltage drops
below about 2.1V to prevent unstable operation.
3411afc
For more information www.linear.com/LTC3411A
9
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| LTC3411EDD | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:否 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 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）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LTC3411EDD#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:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LTC3411EDD#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LTC3411EDD#TR | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:否 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:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 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）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
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