- 您现在的位置：买卖IC网 > PDF目录69007 > LTC3547BIDDB#PBF (LINEAR TECHNOLOGY CORP) 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 PDF资料下载
参数资料
| 型号： | LTC3547BIDDB#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封装： | 3 X 2 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, M0-229WECD-1, DFN-8 |
| 文件页数： | 14/16页 |
| 文件大小： | 248K |
| 代理商： | LTC3547BIDDB#PBF |
LTC3547B
7
3547bfb
OPERATIO
U
The LTC3547B uses a constant-frequency current mode
architecture. The operating frequency is set at 2.25MHz.
Both channels share the same clock and run in-phase.
The output voltage is set by an external resistor divider
returned to the VFB pins. An error amplier compares the
divided output voltage with a reference voltage of 0.6V and
regulates the peak inductor current accordingly.
Main Control Loop
During normal operation, the top power switch (P-channel
MOSFET) is turned on at the beginning of a clock cycle
when the VFB voltage is below the reference voltage. The
current into the inductor and the load increases until the
peak inductor current (controlled by ITH) is reached. The
RS latch turns off the synchronous switch and energy
stored in the inductor is discharged through the bottom
switch (N-channel MOSFET) into the load until the next
clock cycle begins, or until the inductor current begins to
reverse (sensed by the IRCMP comparator).
The peak inductor current is controlled by the internally
compensated ITH voltage, which is the output of the er-
ror amplier. This amplier regulates the VFB pin to the
internal 0.6V reference by adjusting the peak inductor
current accordingly.
At very low load currents, the LTC3547B automatically
transitions from constant frequency operation to discon-
tinuous operation, where the regulator begins skipping
pulses. Even though the total power loss decreases with
load, the efciency of the switching regulator will drop,
because the power delivered to the output becomes very
small. For applications where light load efciency is a
priority, consider using the LTC3547 instead.
Dropout Operation
When the input supply voltage decreases toward the out-
put 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 drops across the internal
P-channel MOSFET and the inductor.
An important design consideration is that the RDS(ON)
of the P-channel switch increases with decreasing input
supply voltage (see Typical Performance Characteristics).
Therefore, the user should calculate the worst-case power
dissipation when the LTC3547B is used at 100% duty cycle
with low input voltage (see Thermal Considerations in the
Applications Information Section).
Soft-Start
In order to minimize the inrush current on the input by-
pass capacitor, the LTC3547B slowly ramps up the output
voltage during start-up. Whenever the RUN1 or RUN2 pin is
pulled high, the corresponding output will ramp from zero
to full-scale over a time period of approximately 650μs. This
prevents the LTC3547B from having to quickly charge the
output capacitor and thus supplying an excessive amount
of instantaneous current.
Short-Circuit Protection
When either regulator output is shorted to ground, the
corresponding internal N-channel switch is forced on for
a longer time period for each cycle in order to allow the
inductor to discharge, thus preventing current runaway.
This technique has the effect of decreasing switching
frequency. Once the short is removed, normal operation
resumes and the regulator output will return to its nominal
voltage.
(Refer to Functional Diagram )
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3560ES6 | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3560ES6#TR | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3560ES6#TRM | 2.1 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3605IUF#PBF | 7.5 A SWITCHING REGULATOR, 4000 kHz SWITCHING FREQ-MAX, PQCC24 |
| LTC3605IUF#TRPBF | 7.5 A SWITCHING REGULATOR, 4000 kHz SWITCHING FREQ-MAX, PQCC24 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3547EDDB | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 300mA Synchronous Step-Down Regulator |
| LTC3547EDDB#PBF | 制造商:Linear Technology 功能描述:REG STEP DOWN 0.3A SYNCH DFN-8 制造商:Linear Technology 功能描述:REG, STEP DOWN, 0.3A SYNCH, DFN-8 |
| LTC3547EDDB#TRMPBF | 功能描述:IC REG BUCK SYNC ADJ .3A DL 8DFN 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 |
| LTC3547EDDB#TRPBF | 功能描述:IC REG BUCK SYNC ADJ .3A DL 8DFN 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 |
| LTC3547EDDB-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual Monolithic 300mA Synchronous Step-Down Regulator |
发布紧急采购，3分钟左右您将得到回复。