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参数资料
| 型号： | LT3481EMSE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/24页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 2A 10MSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.27 V ~ 20 V |
| 输入电压： | 3.6 V ~ 34 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 300kHz ~ 2.8MHz |
| 电流 - 输出： | 2A |
| 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： | 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 |
LT3481
APPLICATIONS INFORMATION
A ?nal precaution regarding ceramic capacitors concerns
the maximum input voltage rating of the LT3481. A ceramic
input capacitor combined with trace or cable inductance
forms a high quality (under damped) tank circuit. If the
LT3481 circuit is plugged into a live supply, the input volt-
age can ring to twice its nominal value, possibly exceeding
the LT3481’s rating. This situation is easily avoided (see
the Hot Plugging Safely section).
Frequency Compensation
The LT3481 uses current mode control to regulate the
output. This simpli?es loop compensation. In particular, the
LT3481 does not require the ESR of the output capacitor
capacitor on the V C pin (C C ) 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 R C in series with C C .
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 (C PL ) 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.
LT3481
for stability, so you are free to use ceramic capacitors to
achieve low output ripple and small circuit size. Frequency
compensation is provided by the components tied to the
V C pin, as shown in Figure 2. Generally a capacitor (C C )
and a resistor (R C ) in series to ground are used. In addi-
tion, there may be lower value capacitor in parallel. This
capacitor (C F ) is not part of the loop compensation but
is used to ?lter noise at the switching frequency, and is
required only if a phase-lead capacitor is used or if the
output capacitor has high ESR.
CURRENT MODE
POWER STAGE
g m = 3.5mho
3Meg
V C
R C
C F
SW
ERROR
AMPLIFIER
FB
g m =
330μmho
1.265V
GND
R1
R2
C PL
ESR
+
C1
POLYMER
OR
TANTALUM
OUTPUT
C1
CERAMIC
Loop compensation determines the stability and transient
performance. Designing the compensation network is
C C
a bit complicated and the best values depend on the
application 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 LT3481 control loop.
The error ampli?er is a transconductance ampli?er with
?nite output impedance. The power section, consisting
I L
1A/DIV
V OUT
100mV/DIV
Figure 2. Model for Loop Response
V OUT = 12V; FRONT PAGE APPLICATION
3481 F02
of the modulator, power switch and inductor, is modeled
10μs/DIV
3481 F03
as a transconductance ampli?er generating an output
current proportional to the voltage at the V C pin. Note that
the output capacitor integrates this current, and that the
Figure 3. Transient Load Response of the LT3481 Front Page
Application as the Load Current is Stepped from 500mA to
1500mA. V OUT = 3.3V
3481fc
13
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| LT3481HDD | 制造商:Linear Technology 功能描述:SW REG 36V 2A 2.8MHZ SD 10DFN |
| LT3481HDD#PBF | 功能描述:IC REG BUCK ADJ 2A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3481HDD#PBF | 制造商:Linear Technology 功能描述:SW REG 36V 2A 2.8MHZ SD 10DFN |
| LT3481HDD#TRPBF | 功能描述:IC REG BUCK ADJ 2A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 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:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3481HDD-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:36V, 2A, 2.8MHz Step-Down Switching Regulator with 50μA Quiescent Current |
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