参数资料
型号: LTC3405ES6#TRPBF
厂商: Linear Technology
文件页数: 12/16页
文件大小: 0K
描述: IC REG BUCK SYNC ADJ .3A SOT23-6
标准包装: 2,500
类型: 降压(降压)
输出类型: 可调式
输出数: 1
输出电压: 0.8 V ~ 6 V
输入电压: 2.5 V ~ 5.5 V
PWM 型: 电流模式,混合
频率 - 开关: 1.5MHz
电流 - 输出: 300mA
同步整流器:
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: SOT-23-6 细型,TSOT-23-6
包装: 带卷 (TR)
供应商设备封装: TSOT-23-6
LTC3405
APPLICATIO S I FOR ATIO
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC3405. These items are also illustrated graphically in
Figures 9 and 10. Check the following in your layout:
1. The power traces, consisting of the GND trace, the SW
trace and the V IN trace should be kept short, direct and
wide.
2. Does the V FB pin connect directly to the feedback
resistors? The resistive divider R1/R2 must be con-
nected between the (+) plate of C OUT and ground.
3. Does the (+) plate of C IN connect to V IN as closely as
4. Keep the switching node, SW, away from the sensitive
V FB node.
Design Example
As a design example, assume the LTC3405 is used in a
single lithium-ion battery-powered cellular phone
application. The V IN will be operating from a maximum of
4.2V down to about 2.7V. The load current requirement
is a maximum of 0.25A but most of the time it will be in
standby mode, requiring only 2mA. Efficiency at both low
and high load currents is important. Output voltage is
2.5V. With this information we can calculate L using
equation (1),
V OUT ? 1 ? OUT ?
possible?ThiscapacitorprovidestheACcurrenttothe
internal power MOSFETs.
1
RUN
MODE
L =
6
1
( ) f ( ? I L )
? V ?
? V IN ?
(3)
LTC3405
2
GND
V FB
5
V OUT
+
C OUT
L1
3
SW
V IN
C IN
4
R2
C FWD
R1
R3*
+
V IN
BOLD LINES INDICATE HIGH CURRENT PATHS
*ADD R3 FOR APPLICATIONS USING A CERAMIC C OUT
Figure 9. LTC3405 Layout Diagram
VIA TO SW NODE
3405 F09
VIA TO GND
R3*
V FB
R1
V OUT
PIN 1
VIA TO V IN
R2
V IN
VIA TO V OUT
L1
SW
C OUT
LTC3405
GND
C IN
C FWD
*ADD R3 WHEN USING CERAMIC C OUT
3405 F10
Figure 10. LTC3405 Suggested Layout
3405fa
12
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