- 您现在的位置：买卖IC网 > PDF目录69007 > LTC3407IMSE-2#TR (LINEAR TECHNOLOGY CORP) 1.6 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO10 PDF资料下载
参数资料
| 型号： | LTC3407IMSE-2#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.6 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封装： | PLASTIC, MSOP-10 |
| 文件页数： | 2/16页 |
| 文件大小： | 227K |
| 代理商： | LTC3407IMSE-2#TR |
LTC3407-2
10
34072fb
APPLICATIONS INFORMATION
Keeping the current small (<5μA) in these resistors maxi-
mizes efciency, 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 feedforward capaci-
tor CF may also be used. Great care should be taken to
route the VFB line away from noise sources, such as the
inductor or the SW line.
Power-On Reset
The POR pin is an open-drain output which pulls low when
either regulator is out of regulation. When both output volt-
ages are within ±8.5% of regulation, a timer is started which
releases POR after 218 clock cycles (about 117ms). This
delay can be signicantly longer in Burst Mode operation
with low load currents, since the clock cycles only occur
during a burst and there could be milliseconds of time
between bursts. This can be bypassed by tying the POR
output to the MODE/SYNC input, to force pulse-skipping
mode during a reset. In addition, if the output voltage
faults during Burst Mode sleep, POR could have a slight
delay for an undervoltage output condition and may not
respond to an overvoltage output. This can be avoided by
using pulse-skipping mode instead. When either channel
is shut down, the POR output is pulled low, since one or
both of the channels are not in regulation.
Mode Selection and Frequency Synchronization
The MODE/SYNC pin is a multipurpose pin which provides
mode selection and frequency synchronization. Connect-
ing this pin to VIN enables Burst Mode operation, which
provides the best low current efciency at the cost of a
higher output voltage ripple. Connecting this pin to ground
selects pulse-skipping mode, which provides the lowest
output ripple, at the cost of low current efciency.
The LTC3407-2 can also be synchronized to an external
LTC3407-2bytheMODE/SYNCpin.Duringsynchronization,
the mode is set to pulse skipping and the top switch turn-on
is synchronized to the rising edge of the external clock.
Checking Transient Response
The regulator loop response can be checked by looking
at the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, VOUT immediately shifts by an amount
equal to ΔILOAD ESR, where ESR is the effective series
resistance of COUT. ΔILOAD also begins to charge or dis-
charge COUT, generating a feedback error signal used by the
regulator to return VOUT to its steady-state value. During
this recovery time, VOUT can be monitored for overshoot
or ringing that would indicate a stability problem.
The initial output voltage step may not be within the
bandwidth of the feedback loop, so the standard second-
order overshoot/DC ratio cannot be used to determine
phase margin. In addition, a feedforward capacitor, CF,
can be added to improve the high frequency response, as
shown in Figure 2. Capacitor CF provides phase lead by
creating a high frequency zero with R2, which improves
the phase margin.
The output voltage settling behavior is related to the stability
of the closed-loop system and will demonstrate the actual
overall supply performance. For a detailed explanation of
optimizing the compensation components, including a re-
view of control loop theory, refer to Application Note 76.
In some applications, a more severe transient can be caused
by switching in loads with large (>1μF) input capacitors.
The discharged input capacitors are effectively put in paral-
lel with COUT, causing a rapid drop in VOUT. No regulator
can deliver enough current to prevent this problem, if the
switch connecting the load has low resistance and is driven
quickly. The solution is to limit the turn-on speed of the
load switch driver. A Hot Swap controller is designed
specically for this purpose and usually incorporates cur-
rent limiting, short-circuit protection, and soft-starting.
Efciency Considerations
The percent efciency of a switching regulator is equal to
the output power divided by the input power times 100%.
It is often useful to analyze individual losses to determine
what is limiting the efciency and which change would
produce the most improvement. Percent efciency can
be expressed as:
%Efciency = 100% - (L1 + L2 + L3 + ...)
where L1, L2, etc. are the individual losses as a percent-
age of input power.
Hot Swap is a registered trademark of Linear Technology Corporation.
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3528BEDDB#TRM | SWITCHING REGULATOR, 1300 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3528EDDB#TRM | SWITCHING REGULATOR, 1300 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3542EDC-1#PBF | SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PDSO6 |
| LTC3547BIDDB#TRM | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
| LTC3547BEDDB-1#PBF | 0.7 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO8 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3408 | 制造商:LINER 制造商全称:Linear Technology 功能描述:1.5MHz, 600mA Synchronous Step-Down Regulator with Bypass Transistor |
| LTC3408EDD | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3408EDD#PBF | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3408EDD#TR | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3408EDD#TRPBF | 功能描述:IC REG BUCK W/BYPASS TXRX 8-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
发布紧急采购，3分钟左右您将得到回复。