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| 型号： | LTC3440EMS#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BST SYNC 0.6A 10MSOP |
| 标准包装： | 50 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 2.5 V ~ 5.5 V |
| 输入电压： | 2.5 V ~ 5.5 V |
| PWM 型： | Burst Mode? |
| 频率 - 开关： | 2MHz |
| 电流 - 输出： | 600mA |
| 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： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 10-MSOP |
| 产品目录页面： | 1334 (CN2011-ZH PDF) |
LTC3440
APPLICATIO S I FOR ATIO
Output Voltage > 4.3V
A Schottky diode from SW to V OUT is required for output
voltages over 4.3V. The diode must be located as close to
the pins as possible in order to reduce the peak voltage on
SW2 due to the parasitic lead and trace inductance.
Closing the Feedback Loop
The LTC3440 incorporates voltage mode PWM control.
The control to output gain varies with operation region
(Buck, Boost, Buck-Boost), but is usually no greater than
15. The output filter exhibits a double pole response is
given by:
Input Voltage > 4.5V
For applications with input voltages above 4.5V which
could exhibit an overload or short-circuit condition, a 2 Ω /
f FILTER _ POLE =
1
2 ? π ? L ? C OUT
Hz ( in Buck mod e )
1nF series snubber is required between the SW1 pin and
GND. A Schottky diode such as the Phillips PMEG2010EA
or equivalent from SW1 to V IN should also be added as
f FILTER _ POLE =
V IN
2 π ? L ? V OUT
Hz ( in Boost mod e )
close to the pins as possible. For the higher input voltages
V IN bypassing becomes more critical, therefore, a ceramic
bypass capacitor as close to the V IN and GND pins as
where C OUT is the output filter capacitor.
The output filter zero is given by:
possible is also required.
Operating Frequency Selection
f FILTER _ ZERO =
1
2 ? π ? R ESR ? C OUT
Hz
There are several considerations in selecting the operating
frequency of the converter. The first is, what are the
sensitive frequency bands that cannot tolerate any spec-
where R ESR is the capacitor equivalent series resistance.
A troublesome feature in Boost mode is the right-half
plane zero (RHP), and is given by:
tral noise? For example, in products incorporating RF
communications, the 455kHz IF frequency is sensitive to
any noise, therefore switching above 600kHz is desired.
Some communications have sensitivity to 1.1MHz and in
f RHPZ
=
2
V IN
2 ? π ? I OUT ? L ? V OUT
Hz
f UG =
2 ? π ? R 1 ? CP 1
that case a 2MHz converter frequency may be employed.
Other considerations are the physical size of the converter
and efficiency. As the operating frequency goes up, the
inductor and filter capacitors go down in value and size.
The trade off is in efficiency since the switching losses due
to gate charge are going up proportional with frequency.
Additional quiescent current due to the output switches
GATE charge is given by:
Buck: 500e –12 ? V IN ? F
Boost: 250e –12 ? (V IN + V OUT ) ? F
Buck/Boost: F ? (750e –12 ? V IN + 250e –12 ? V OUT )
where F = switching frequency
The loop gain is typically rolled off before the RHP zero
frequency.
A simple Type I compensation network can be incorpo-
rated to stabilize the loop but at a cost of reduced band-
width and slower transient response. To ensure proper
phase margin, the loop requires to be crossed over a
decade before the LC double pole.
The unity-gain frequency of the error amplifier with the
Type I compensation is given by:
1
Hz
Most applications demand an improved transient response
to allow a smaller output filter capacitor. To achieve a
higher bandwidth, Type III compensation is required. Two
zeros are required to compensate for the double-pole
response.
3440fb
13
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| LTC3441 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Current Micropower Synchronous Buck-Boost DC/DC Converter |
| LTC3441EDE | 功能描述:IC REG BUCK BOOST SYNC ADJ 12DFN 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 |
| LTC3441EDE#PBF | 功能描述:IC REG BUCK BOOST SYNC ADJ 12DFN 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 |
| LTC3441EDE#TR | 功能描述:IC REG BUCK BOOST SYNC ADJ 12DFN 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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