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| 型号： | LT3688EFE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 17/28页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.8A DL 24TSSOP |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 2 |
| 输出电压： | 0.8 V ~ 32.4 V |
| 输入电压： | 3.8 V ~ 36 V |
| PWM 型： | 电流模式，Burst Mode? |
| 频率 - 开关： | 500kHz ~ 2.1MHz |
| 电流 - 输出： | 800mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 24-TSSOP |
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LT3688
APPLICATIONS INFORMATION
Table 4. Capacitor Vendors
With the recommended output capacitor, the loop cross-
Part Number
V R
(V)
I AVE
(A)
V F at 1A
(mV)
over occurs above the R C C C zero. This simple model works
well as long as the value of the inductor is not too high
On Semiconductor
and the loop crossover frequency is much lower than the
MBR0520L
20
0.5
switching frequency. With a larger ceramic capacitor (very
MBR0540
MBRM120E
MBRM140
40
20
40
0.5
1
1
620
530
550
low ESR), crossover may be lower and a phase lead ca-
pacitor (C PL ) across the feedback divider may improve the
phase margin and transient response. At minimum, use a
Diodes Inc.
10pF phase lead capacitor to reduce noise injection to the
B0530W
30
0.5
FB pin. If the output capacitor is different than the recom-
B120
B130
B140HB
DFLS140
20
30
40
40
1
1
1
1.1
500
500
510
mended capacitor, stability should 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 4
Ceramic Capacitors
Ceramic capacitors are small, robust and have very low
shows the transient response when the load current is
stepped from 300mA to 600mA and back to 300mA.
0.7V
R C
3M ERROR
ESR. However, ceramic capacitors can cause problems
when used with the LT3688 due to their piezoelectric
nature. When in Burst Mode operation, the LT3688’s
switching frequency depends on the load current, and
at very light loads the LT3688 can excite the ceramic
capacitor at audio frequencies, generating audible noise.
Since the LT3688 operates at a lower current limit during
Burst Mode operation, the noise is typically very quiet. If
LT3688 CURRENT MODE
80k
C C
100pF
GND
POWER STAGE
g m =
1.6A/V
FB
V C g m =
300μA/V
800mV
AMPLIFIER
R1
R2
C PL
+
OUT
ESR
C1
C1
TANTALUM OR CERAMIC
ELECTROLYTIC
this is unacceptable, use a high performance tantalum or
electrolytic capacitor at the output.
Frequency Compensation
The LT3688 uses current mode control to regulate the
output, which simpli?es loop compensation. In particular,
the LT3688 does not require the ESR of the output capaci-
tor for stability, allowing the use of ceramic capacitors to
achieve low output ripple and small circuit size. Figure 3
shows an equivalent circuit for the LT3688 control loop. The
error amp is a transconductance ampli?er with ?nite output
3688 F03
Figure 3. Model for the Loop Response
V OUT
100mV/DIV
I LOAD
200mA/DIV
impedance. The power section, consisting of the modulator,
50μs/DIV
3688 F04
power switch and inductor, is modeled as a transconduc-
tance ampli?er generating an output current proportional to
the voltage at the V C node. Note that the output capacitor,
Figure 4. Transient Load Response of the LT3688
Front Page Application as the Load Current is
Stepped from 300mA to 600mA
C1, integrates this current, and that the capacitor on the
V C node (C C ) integrates the error ampli?er output current,
resulting in two poles in the loop. R C provides a zero.
3688f
17
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| LT3688EUF#TRPBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24QFN 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 |
| LT3688EUFPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Dual 800mA Step-Down Switching Regulator with Power-On Reset |
| LT3688HFE#PBF | 功能描述:IC REG BUCK ADJ 0.8A DL 24TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:MIC23xxx HyperLight Load™ Regulators 标准包装:5,000 系列:HyperLight Load® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.8V 输入电压:2.7 V ~ 5.5 V PWM 型:混合物 频率 - 开关:4MHz 电流 - 输出:2A 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:8-VFDFN 裸露焊盘，8-MLF? 包装:带卷 (TR) 供应商设备封装:8-MLF?（2x2） 产品目录页面:1094 (CN2011-ZH PDF) 其它名称:576-3303-2 |
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