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參數資料
| 型號： | LT3470AIDDB#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 0.56 A SWITCHING REGULATOR, PDSO8 |
| 封裝： | 3 X 2 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, MO-229WECD-1, DFN-8 |
| 文件頁數： | 19/20頁 |
| 文件大?。?/td> | 197K |
| 代理商： | LT3470AIDDB#PBF |
LT3470A
8
3470afb
Figure 1. Operating Waveforms of the LT3470A Converting 12V to 5V Using a 33μH Inductor and 10μF Output Capacitor
OPERATION
The LT3470A uses a hysteretic control scheme in conjunc-
tion with Burst Mode operation to provide low output ripple
and low quiescent current while using a tiny inductor and
capacitors.
Operation can best be understood by studying the Block
Diagram. An error amplifier measures the output voltage
through an external resistor divider tied to the FB pin. If
the FB voltage is higher than VREF, the error amplifier will
shut off all the high power circuitry, leaving the LT3470A
in its micropower state. As the FB voltage falls, the error
amplifier will enable the power section, causing the chip
to begin switching, thus delivering charge to the output
capacitor. If the load is light the part will alternate between
micropower and switching states to keep the output in
regulation (See Figure 1a). At higher loads the part will
switch continuously while the error amp servos the top
and bottom current limits to regulate the FB pin voltage
to 1.25V (See Figure 1b).
The switching action is controlled by an RS latch and
two current comparators as follows: The switch turns on,
and the current through it ramps up until the top current
comparator trips and resets the latch causing the switch
to turn off. While the switch is off, the inductor current
ramps down through the catch diode. When both the bot-
tom current comparator trips and the minimum off-time
one-shot expires, the latch turns the switch back on thus
completing a full cycle. The hysteretic action of this control
scheme results in a switching frequency that depends
on inductor value, input and output voltage. Since the
switch only turns on when the catch diode current falls
below threshold, the part will automatically switch slower
to keep inductor current under control during start-up or
short-circuit conditions.
The switch driver operates from either the input or from
the BOOST pin. An external capacitor and internal diode
is used to generate a voltage at the BOOST pin that is
higher than the input supply. This allows the driver to
fully saturate the internal bipolar NPN power switch for
efficient operation.
If the SHDN pin is grounded, all internal circuits are turned
off and VIN current reduces to the device leakage current,
typically 100nA.
(1a) Burst Mode Operation
(1b) Continuous Operation
VOUT
20mV/DIV
IL
100mA/DIV
1ms/DIV
VOUT
20mV/DIV
IL
100mA/DIV
5μs/DIV
3470a F01a
NO LOAD
10mA LOAD
VOUT
20mV/DIV
IL
100mA/DIV
1μs/DIV
VOUT
20mV/DIV
IL
100mA/DIV
1μs/DIV
3470a F1b
200mA LOAD
150mA LOAD
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LT3470AIDDB-TRPBF | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Micropower Buck Regulator with Integrated Boost and Catch Diodes |
| LT3470EDDB | 制造商:Linear Technology 功能描述:Conv DC-DC Single Step Down 4V to 40V 8-Pin DFN EP |
| LT3470EDDB#PBF | 制造商:Linear Technology 功能描述:BUCK 40V 0.3A 8DFN 制造商:Linear Technology 功能描述:BUCK, 40V, 0.3A, 8DFN |
| LT3470EDDB#TRMPBF | 功能描述:IC REG BUCK ADJ 0.2A 8DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調式 輸出數:1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關:600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應商設備封裝:8-SOIC |
| LT3470EDDB#TRPBF | 功能描述:IC REG BUCK ADJ 0.2A 8DFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調式 輸出數:1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關:600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應商設備封裝:8-SOIC |
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