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参数资料
| 型号： | LTC3440EDD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 8/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BOOST SYNC ADJ 10DFN |
| 标准包装： | 2,500 |
| 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-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-DFN（3x3） |
LTC3440
OPERATIO
f = ?
? R T ?
The LTC3440 provides high efficiency, low noise power
for applications such as portable instrumentation. The
LTC proprietary topology allows input voltages above,
below or equal to the output voltage by properly phasing
the output switches. The error amp output voltage on the
V C pin determines the output duty cycle of the switches.
Since the V C pin is a filtered signal, it provides rejection of
frequencies from well below the switching frequency. The
low R DS(ON) , low gate charge synchronous switches pro-
vide high frequency pulse width modulation control at
high efficiency. Schottky diodes across the synchronous
switch D and synchronous switch B are not required, but
provide a lower drop during the break-before-make time
(typically 15ns). The addition of the Schottky diodes will
improve peak efficiency by typically 1% to 2% at 600kHz.
High efficiency is achieved at light loads when Burst Mode
operation is entered and when the IC’s quiescent current
is a low 25 μ A.
LOW NOISE FIXED FREQUENCY OPERATION
Oscillator
The frequency of operation is user programmable and is
set through a resistor from the R T pin to ground where:
? 6 e 10 ?
? Hz
An internally trimmed timing capacitor resides inside the
IC. The oscillator can be synchronized with an external
clock applied to the MODE/SYNC pin. A clock frequency of
twice the desired switching frequency and with a pulse
width between 100ns and 2 μ s is applied. The oscillator R T
Error Amp
The error amplifier is a voltage mode amplifier. The loop
compensation components are configured around the
amplifier to provide loop compensation for the converter.
The SHDN/SS pin will clamp the error amp output, V C , to
provide a soft-start function.
Supply Current Limit
The current limit amplifier will shut PMOS switch A off
once the current exceeds 2.7A typical. The current ampli-
fier delay to output is typically 50ns.
Reverse Current Limit
The reverse current limit amplifier monitors the inductor
current from the output through switch D. Once a negative
inductor current exceeds – 400mA typical, the IC will shut
off switch D.
Output Switch Control
Figure 1 shows a simplified diagram of how the four
internal switches are connected to the inductor, V IN , V OUT
and GND. Figure 2 shows the regions of operation for the
LTC3440 as a function of the internal control voltage, V CI .
The V CI voltage is a level shifted voltage from the output of
the error amp (V C pin) (see Figure 5). The output switches
are properly phased so the transfer between operation
modes is continuous, filtered and transparent to the user.
When V IN approaches V OUT the Buck/Boost region is
reached where the conduction time of the four switch
region is typically 150ns. Referring to Figures 1 and 2, the
various regions of operation will now be described.
component value required is given by:
V IN
V OUT
7
6
V OUT
R T =
8 ? 10 10
f SW
PMOS A
SW1
SW2
PMOS D
3
4
where f SW = desired synchronized switching frequency.
For example to achieve a 1.2MHz synchronized switching
NMOS B
NMOS C
frequency the applied clock frequency to the MODE/SYNC
pin is set to 2.4MHz and the timing resistor, R T , is set to
66.5k (closest 1% value).
3440 F01
Figure 1. Simplified Diagram of Output Switches
3440fb
8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3440EMS | 功能描述:IC REG BUCK BST SYNC 0.6A 10MSOP 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: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 |
| LTC3440EMS#PBF | 功能描述:IC REG BUCK BST SYNC 0.6A 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: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 |
| LTC3440EMS#TR | 功能描述:IC REG BUCK BST SYNC 0.6A 10MSOP 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 |
| LTC3440EMS#TRPBF | 功能描述:IC REG BUCK BST SYNC 0.6A 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: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 |
| LTC3440EMSPBF | 制造商:Linear Technology 功能描述:LTC3440 adj 600mA SU/SD dc-dc converter |
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