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参数资料
| 型号： | LT3470AHDDB#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.56 A SWITCHING REGULATOR, PDSO8 |
| 封装： | 3 X 2 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, MO-229WECD-1, DFN-8 |
| 文件页数： | 4/20页 |
| 文件大小： | 197K |
| 代理商： | LT3470AHDDB#TRPBF |
LT3470A
12
3470afb
APPLICATIONS INFORMATION
(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 LT3470A monitors the boost capacitor for sufficient
voltage such that the switch is allowed to fully saturate.
When boost voltage falls below adequate levels (1.8V
typical) the switch will operate with about 1V of drop, and
an internal current source will begin to pull 50mA (typi-
cal) from the BIAS pin which is typically connected to the
output. This current forces the LT3470A to switch more
often and with more inductor current, which recharges
the boost capacitor. When the boost capacitor voltage is
above 1.8V (typical) the current source turns off, and the
part may enter BurstMode. This cycle will repeat anytime
there is an undervoltage condition on the boost capaci-
tor. See Figure 3 for minimum input voltage for outputs
of 3.3V and 5V.
Shorted Input Protection
If the inductor is chosen so that it won’t saturate exces-
sively at the top switch current limit maximum of 525mA,
an LT3470A buck regulator will tolerate a shorted output
even if VIN = 40V. There is another situation to consider
in systems where the output will be held high when the
input to the LT3470A 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
LT3470A’s output. If the VIN pin is allowed to float and the
SHDN pin is held high (either by a logic signal or because
it is tied to VIN), then the LT3470A’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 VIN pin is grounded while
the output is held high, then parasitic diodes inside the
LT3470A can pull large currents from the output through
the SW pin and the VIN 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.
Figure 3. The Minimum Input Voltage Depends on Output
Voltage, Load Current and Boost Circuit
Minimum Input Voltage, VOUT = 3.3V
Minimum Input Voltage, VOUT = 5V
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 LT3470A Runs Only When the Input is
Present Hot-Plugging Safely
VIN
BOOST
LT3470A
SW
SHDN
3470a F04
VIN
100k
D1
1M
VOUT
BACKUP
BIAS
FB
GND
LOAD CURRENT (mA)
0
3.0
INPUT
VOLTAGE
(V)
3.5
4.0
4.5
5.0
5.5
6.0
50
100
150
200
250
3470a F03a
TA = 25°C
VIN TO RUN/START
LOAD CURRENT (mA)
0
INPUT
VOLTAGE
(V)
6
7
250
3470a F03b
5
4
50
100
150
200
8
TA = 25°C
VIN TO RUN/START
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3470AIDDB#PBF | 制造商:Linear Technology 功能描述:Bulk |
| LT3470AIDDB#TRMPBF | 功能描述:IC REG BUCK ADJ 0.25A 8DFN 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 |
| LT3470AIDDB#TRPBF | 功能描述:IC REG BUCK ADJ 0.25A 8DFN 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 |
| LT3470AIDDB-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Buck Regulator with Integrated Boost and Catch Diodes |
| LT3470AIDDB-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Buck Regulator with Integrated Boost and Catch Diodes |
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