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参数资料
| 型号： | LT3681EDE#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 4.4 A SWITCHING REGULATOR, 3100 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封装： | 4 X 3 MM, PLASTIC, DFN-14 |
| 文件页数： | 5/24页 |
| 文件大小： | 367K |
| 代理商： | LT3681EDE#TR |
LT3681
13
3681f
Loop compensation determines the stability and transient
performance. Designing the compensation network is a
bit complicated and the best values depend on the ap-
plication and in particular the type of output capacitor. A
practical approach is to start with one of the circuits in
this data sheet that is similar to your application and tune
the compensation network to optimize the performance.
Stability should then be checked across all operating
conditions, including load current, input voltage and
temperature. The LT1375 data sheet contains a more
thorough discussion of loop compensation and describes
how to test the stability using a transient load. Figure 2
shows an equivalent circuit for the LT3681 control loop.
The error amplier is a transconductance amplier with
nite output impedance. The power section, consisting of
the modulator, power switch and inductor, is modeled as
a transconductance amplier generating an output cur-
rent proportional to the voltage at the VC pin. Note that
the output capacitor integrates this current, and that the
capacitor on the VC pin (CC) integrates the error ampli-
er output current, resulting in two poles in the loop. In
most cases a zero is required and comes from either the
output capacitor ESR or from a resistor RC in series with
CC. This simple model works well as long as the value
of the inductor is not too high and the loop crossover
frequency is much lower than the switching frequency.
A phase lead capacitor (CPL) across the feedback divider
may improve the transient response. Figure 3 shows the
transient response when the load current is stepped from
500mA to 1500mA and back to 500mA.
Burst Mode Operation
To enhance efciency at light loads, the LT3681 auto-
matically switches to Burst Mode operation which keeps
the output capacitor charged to the proper voltage while
minimizing the input quiescent current. During Burst Mode
operation, the LT3681 delivers single cycle bursts of current
to the output capacitor followed by sleep periods where
the output power is delivered to the load by the output
capacitor. In addition, VIN and BIAS quiescent currents are
reduced to typically 20A and 50A respectively during
the sleep time. As the load current decreases towards a
no load condition, the percentage of time that the LT3681
operates in sleep mode increases and the average input
current is greatly reduced resulting in higher efciency.
See Figure 4.
–
+
1.265V
SW
VC
GND
3Meg
LT3681
3681 F02
R1
OUTPUT
ESR
CF
CC
RC
ERROR
AMPLIFIER
FB
R2
C1
CURRENT MODE
POWER STAGE
gm = 3.5mho
gm =
330
mho
+
POLYMER
OR
TANTALUM
CERAMIC
CPL
Figure 2. Model for Loop Response
Figure 3. Transient Load Response of the LT3681 3.3V Application
as the Load Current is Stepped from 500mA to 1500mA.
3681 F03
IL
1A/DIV
VOUT
100mV/DIV
10
ms/DIV
VIN = 12V
APPLICATIONS INFORMATION
Figure 4. Burst Mode Operation
3681 F04
IL
0.5A/DIV
VSW
5V/DIV
VOUT
10mV/DIV
5
ms/DIV
VIN = 12V; VOUT = 3.3V
ILOAD = 10mA
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3682 | 制造商:LINER 制造商全称:Linear Technology 功能描述:42V, 750mA Step-Down Regulator with 2.5μA |
| LT3682EDD#PBF | 功能描述:IC REG BUCK ADJ 1A 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 |
| LT3682EDD#TRPBF | 功能描述:IC REG BUCK ADJ 1A 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: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 |
| LT3682EDD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1A Micropower Step-Down |
| LT3682EDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:1A Micropower Step-Down |
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