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参数资料
| 型号： | LT3645IUD#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 1.25 A SWITCHING REGULATOR, 825 kHz SWITCHING FREQ-MAX, PQCC16 |
| 封装： | 3 X 3 MM, LEAD FREE, PLASTIC, MO-220WEED-2, QFN-16 |
| 文件页数： | 6/24页 |
| 文件大小： | 296K |
| 代理商： | LT3645IUD#TRPBF |
LT3645
14
3645f
APPLICATIONS INFORMATION
pull large currents from the output through the SW pin
and the VIN pin. Figure 5 shows a circuit that will run only
when the input voltage is present and that protects against
a shorted or reversed input.
Frequency Compensation (Buck)
The LT3645 uses current mode control to regulate the
loop. This simplies loop compensation. In particular, the
LT3645 does not require the ESR of the output capacitor
for stability, allowing the use of ceramic capacitors to
achieve low output ripple and small circuit size. A low
ESR output capacitor will typically provide for a greater
margin of circuit stability than an otherwise equivalent
capacitor with higher ESR, although the higher ESR will
tend to provide a faster loop response. Figure 6 shows an
equivalent circuit for the LT3645 control loop.
Figure 5. Diode D4 Prevents a Shorted Input from Discharging a
Backup Battery Tied to the Output; It Also Protects the Circuit from
a Reversed Input. The LT3645 Runs Only When the Input Is Present
Figure 6. Model for Loop Response
The error amplier (gm) is a transconductance type with
nite output impedance. The power section, consisting
of the modulator, power switch, and inductor, is modeled
as a transconductance amplier (G) generating an output
current proportional to the voltage at the VC node. Note
that the output capacitor integrates this current, and that
the capacitor on the VC node (CC) integrates the error
amplier output current, resulting in two poles in the
loop. RC provides a zero. With the recommended output
capacitor, the loop crossover occurs above the RCCC zero.
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. With a larger
ceramic capacitor that will have lower ESR, crossover may
be lower and a phase lead capacitor connected across
R1 in the feedback divider may improve the transient
response. Large electrolytic capacitors may have an ESR
3645 F05
VIN
D4
GND
SW
DA
VCC2
NPG
FB
OUT2
VIN
EN/UVLO
EN2
FB2
BACKUP
BOOST
LT3645
G
RC
R1
R2
gm = 100μA/V
G = 1A/V
RC = 150k
CC = 60pF
OUT
COUT
CERAMIC
CC
1M
0.8V
gm
CPL
ELECTROLYTIC
ESR
+
3645 F06
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相关代理商/技术参数 |
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|---|---|
| LT3650 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage High Current Controller for Battery Charging and Power Management |
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| LT3650-4.2 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage 2 Amp Monolithic Li-Ion Battery Charger |
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| LT3650EDD-4.1#PBF | 功能描述:IC CHARGER LI-ION 2A 12-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 其它有关文件:STC3100 View All Specifications 特色产品:STC3100 - Battery Monitor IC 标准包装:4,000 系列:- 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MiniSO 包装:带卷 (TR) 其它名称:497-10526-2 |
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