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参数资料
| 型号： | LT3470HDDB#TR |
| 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： | 4/16页 |
| 文件大小： | 244K |
| 代理商： | LT3470HDDB#TR |
12
LT3470
3470fb
SHDN
VIN
VOUT
(A)
(B)
VOUT
3470 F05
GND
SHDN
VIN
GND
C1
C2
VIAS TO FEEDBACK DIVIDER
VIAS TO LOCAL GROUND PLANE
OUTLINE OF LOCAL GROUND PLANE
PCB Layout
For proper operation and minimum EMI, care must be
taken during printed circuit board layout. Note that large,
switched currents flow in the power switch, the internal
catch diode and the input capacitor. The loop formed by
these components should be as small as possible. Fur-
thermore, the system ground should be tied to the regu-
lator ground in only one place; this prevents the switched
current from injecting noise into the system ground.
These components, along with the inductor and output
capacitor, should be placed on the same side of the circuit
board, and their connections should be made on that layer.
Place a local, unbroken ground plane below these compo-
nents, and tie this ground plane to system ground at one
location, ideally at the ground terminal of the output
capacitor C2. Additionally, the SW and BOOST nodes
should be kept as small as possible. Unshielded inductors
can induce noise in the feedback path resulting in instabil-
ity and increased output ripple. To avoid this problem, use
vias to route the VOUT trace under the ground plane to the
feedback divider (as shown in Figure 5). Finally, keep the
FB node as small as possible so that the ground pin and
ground traces will shield it from the SW and BOOST nodes.
Figure 5 shows component placement with trace, ground
plane and via locations. Include vias near the GND pin, or
pad, of the LT3470 to help remove heat from the LT3470
to the ground plane.
Hot-Plugging Safely
The small size, robustness and low impedance of ceramic
capacitors make them an attractive option for the input
bypass capacitor of LT3470. However, these capacitors
can cause problems if the LT3470 is plugged into a live
supply (see Linear Technology Application Note 88 for a
complete discussion). The low loss ceramic capacitor
combined with stray inductance in series with the power
source forms an under damped tank circuit, and the
voltage at the VIN pin of the LT3470 can ring to twice the
nominal input voltage, possibly exceeding the LT3470’s
rating and damaging the part. If the input supply is poorly
controlled or the user will be plugging the LT3470 into an
energized supply, the input network should be designed to
prevent this overshoot. Figure 6 shows the waveforms
that result when an LT3470 circuit is connected to a 24V
supply through six feet of 24-gauge twisted pair. The first
plot is the response with a 2.2
F ceramic capacitor at the
input. The input voltage rings as high as 35V and the input
current peaks at 20A. One method of damping the tank
circuit is to add another capacitor with a series resistor to
the circuit. In Figure 6b an aluminum electrolytic capacitor
has been added. This capacitor’s high equivalent series
resistance damps the circuit and eliminates the voltage
overshoot. The extra capacitor improves low frequency
ripple filtering and can slightly improve the efficiency of
Figure 5. A Good PCB Layout Ensures Proper, Low EMI Operation
APPLICATIO S I FOR ATIO
WU
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| LT3470HTS8#TRPBF | 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 |
| LT3470IDDB | 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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