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参数资料
| 型号： | LT3470HDDB |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 0.2 A SWITCHING REGULATOR, PDSO8 |
| 封装： | 3 X 2 MM, 0.75MM INCH HEIGHT, MO-229WECD-1, PLASTIC, DFN-8 |
| 文件页数： | 19/20页 |
| 文件大小： | 256K |
| 代理商： | LT3470HDDB |
8
LT3470
3470fc
OPERATIO
U
The LT3470 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 induc-
tor 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 LT3470 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 bottom
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 a few nA.
(1a) Burst Mode Operation
(1b) Continuous Operation
Figure 1. Operating Waveforms of the LT3470 Converting 12V to 5V Using a 33
H Inductor and 10F Output Capacitor
VOUT
20mV/DIV
IL
100mA/DIV
1ms/DIV
VOUT
20mV/DIV
IL
100mA/DIV
5
s/DIV
3470 F01a
NO LOAD
10mA LOAD
VOUT
20mV/DIV
IL
100mA/DIV
1
s/DIV
VOUT
20mV/DIV
IL
100mA/DIV
1
s/DIV
3470 F1b
200mA LOAD
150mA LOAD
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3470HDDB#TRMPBF | 功能描述:IC REG BUCK ADJ 0.2A 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 |
| LT3470HDDB#TRPBF | 功能描述:IC REG BUCK ADJ 0.2A 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 |
| LT3470HTS8 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Buck Regulator with Integrated Boost and Catch Diodes |
| LT3470HTS8#PBF | 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic, Cut Tape 300mA, 40V MicroPower Step-Down Regulator with Int |
| LT3470HTS8#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: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 |
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