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| 型号： | LT3470IDDB#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 12/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.2A 8DFN |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.25 V ~ 16 V |
| 输入电压： | 4 V ~ 40 V |
| PWM 型： | Burst Mode? |
| 电流 - 输出： | 200mA |
| 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： | 8-WFDFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 8-DFN（3x2） |
| 其它名称： | LT3470IDDB#TRMPBFDKR |
LT3470
APPLICATIONS INFORMATION
T A = 25°C
(Figure 2b). The circuit in Figure 2a is more efficient
because the BOOST pin current and BIAS pin quiescent
current comes from a lower voltage source. You must also
be sure that the maximum voltage ratings of the BOOST
and BIAS pins are not exceeded.
The minimum operating voltage of an LT3470 application
is limited by the undervoltage lockout (4V) and by the
maximum duty cycle as outlined in a previous section. For
proper start-up, the minimum input voltage is also limited
by the boost circuit. If the input voltage is ramped slowly,
or the LT3470 is turned on with its SHDN pin when the
output is already in regulation, then the boost capacitor may
not be fully charged. The plots in Figure 3 show minimum
Minimum Input Voltage, V OUT = 3.3V
6.0
V IN TO START
5.5
5.0
4.5
4.0
V IN TO RU N
3.5
3.0
0 50 100 150 200
LOAD CURRENT (mA)
3470 G18
Minimum Input Voltage, V OUT = 5V
V IN to start and to run. At light loads, the inductor current
becomes discontinuous and the effective duty cycle can
be very high. This reduces the minimum input voltage to
approximately 300mV above V OUT . At higher load currents,
the inductor current is continuous and the duty cycle is
limited by the maximum duty cycle of the LT3470, requiring
a higher input voltage to maintain regulation.
Shorted Input Protection
If the inductor is chosen so that it won’t saturate exces-
sively at the top switch current limit maximum of 450mA,
an LT3470 buck regulator will tolerate a shorted output
even if V IN = 40V. There is another situation to consider
in systems where the output will be held high when the
input to the LT3470 is absent. This may occur in battery
charging applications or in battery backup systems where
a battery or some other supply is diode OR-ed with the
LT3470’s output. If the V IN pin is allowed to float and the
SHDN pin is held high (either by a logic signal or because
it is tied to V IN ), then the LT3470’s internal circuitry will
pull its quiescent current through its SW pin. This is fine
if your system can tolerate a few mA in this state. If you
ground the SHDN pin, the SW pin current will drop to es-
sentially zero. However, if the V IN pin is grounded while
the output is held high, then parasitic diodes inside the
LT3470 can pull large currents from the output through
the SW pin and the V IN pin. Figure 4 shows a circuit that
will run only when the input voltage is present and that
protects against a shorted or reversed input.
8
7
T A = 25°C
V IN TO START
V IN
D1
V IN
BOOST
6
5
V IN TO RUN
100k
1M
LT3470 SOT-23
SHDN SW
BIAS
FB
GND
V OUT
BACKUP
4
0
50
100
150
200
3470 F04
LOAD CURRENT (mA)
3470 G19
Figure 3. The Minimum Input Voltage Depends on Output
Voltage, Load Current and Boost Circuit
Figure 4. Diode D1 Prevents a Shorted Input from Discharging a
Backup Battery Tied to the Output; It Also Protects the Circuit
from a Reversed Input. The LT3470 Runs Only When the Input Is
Present Hot-Plugging Safely
3470fd
12
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相关代理商/技术参数 |
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|---|---|
| LT3470ITS8 | 制造商:LINEAR 制造商全称:LINEAR 功能描述:Micropower Buck Regulator with Integrated Boost and Catch Diodes |
| LT3470ITS8#PBF | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 40V 8-Pin TSOT-23 制造商:Linear Technology 功能描述:IC BUCK REGULATOR 8-TSOT-23 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic, Cut Tape 300mA, 40V Micropower Step-Down Reg in ThinSOT 制造商:Linear Technology 功能描述:IC, BUCK REGULATOR, 8-TSOT-23, Primary Input Voltage:40V, No. of Outputs:1, Output Voltage:16V, Output Current:200mA, No. of Pins:8, Operating Temperature Min:-40C, Operating Temperature Max:125C, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes |
| LT3470ITS8#TR | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 40V 8-Pin TSOT-23 T/R 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic, 300mA, 40V Micropower Step-Down Reg in ThinSOT |
| LT3470ITS8#TRM | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 40V 8-Pin TSOT-23 T/R |
| LT3470ITS8#TRMPBF | 功能描述:IC REG BUCK ADJ 0.2A TSOT23-8 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 |
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