- 您现在的位置：买卖IC网 > PDF目录1829 > LTC3408EDD#TRPBF (Linear Technology)IC REG BUCK W/BYPASS TXRX 8-DFN PDF资料下载
参数资料
| 型号： | LTC3408EDD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK W/BYPASS TXRX 8-DFN |
| 标准包装： | 2,500 |
| 应用： | 转换器，WCDMA 功率放大器应用 |
| 输入电压： | 2.5 V ~ 5 V |
| 输出数： | 1 |
| 输出电压： | 0.3 V ~ 3.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-WFDFN 裸露焊盘 |
| 供应商设备封装： | 8-DFN-EP（3x3） |
| 包装： | 带卷 (TR) |
LTC3408
APPLICATIO S I FOR ATIO
dissipate (0.531A) 2 ? 0.08 ? = 22.6mW. Thus, T J = 70 ° C +
(0.0143 + 0.0425)(43) = 71.1 ° C.
Reductions in power dissipation occur at higher supply
voltages, where the junction temperature is lower due to
reduced switch resistance (R DS(ON) ).
Checking Transient Response
The regulator loop response can be checked by looking at
the load transient response. Switching regulators take
several cycles to respond to a step in load current. When
a load step occurs, V OUT immediately shifts by an amount
equal to (I LOAD ? ESR), where ESR is the effective series
resistance of C OUT . I LOAD also begins to charge or dis-
charge C OUT , which generates a feedback error signal. The
regulator loop then acts to return V OUT to its steady state
value. During this recovery time V OUT can be monitored for
overshoot or ringing that would indicate a stability prob-
lem. For a detailed explanation of switching control loop
theory, see Application Note 76.
A second, more severe transient is caused by switching in
loads with large (>1 μ F) supply bypass capacitors. The
discharged bypass capacitors are effectively put in parallel
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC3408. These items are also illustrated graphically in
Figures 5 and 6. 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 (+) plate of C IN connect to V IN as closely as
possible? This capacitor provides the AC drive to the
internal power MOSFETs.
3. Keep the (–) plates of C IN and C OUT as close as possible.
Design Example
As a design example, assume the LTC3408 is used in a
single lithium-ion battery-powered cellular phone applica-
tion. 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 0.6A 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 ?
withC OUT ,causingarapiddropinV OUT .Noregulatorcan
deliver enough current to prevent this problem if the load
switch resistance is low and it is driven quickly. The only
solution is to limit the rise time of the switch drive so that
L =
1
( f )( ? I L )
? V ?
? V IN ?
(2)
the load rise time is limited to approximately (25 ? C LOAD ).
Thus, a 10 μ F capacitor charging to 3.3V would require a
250 μ s rise time, limiting the charging current to about
TO DAC
R REF
VIA TO REF
130mA.
1
V OUT
V OUT
8
C OUT
V OUT
C IN
VIA TO PIN 8
C OUT
VIA TO PIN 1
V IN
2 V IN
V IN
7
R REF
DAC
V OUT
1
8
V OUT
VIA TO PIN 2
C IN
3
4
GND
SW
REF
RUN
6
5
C REF
VIA TO PIN 7
V IN
GND
SW
2
3
4
LTC3408
7
6
5
V IN
REF
RUN
C REF
LTC3408
BOLD LINES INDICATE HIGH CURRENT PATHS
3403 F05
L1
VIA TO V IN VIA TO GND
3408 F06
Figure 5. Layout Diagram
Figure 6. Suggested Layout
3408f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3409IDD#TRPBF | IC REG BUCK SYNC ADJ 0.6A 8DFN |
| LTC3410BESC6-1.8#TRPBF | IC REG BUCK SYNC 1.8V .3A SC70-6 |
| LTC3411AIMS#TRPBF | IC REG BUCK SYNC ADJ 10MSOP |
| LTC3411IMS#TRPBF | IC REG BUCK SYNC ADJ 10MSOP |
| LTC3412IFE#TRPBF | IC REG BUCK SYNC ADJ 16TSSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3409 | 制造商:LINER 制造商全称:Linear Technology 功能描述:600mA Low Vin Buck Regulator in 3mm x 3mm DFN |
| LTC3409A | 制造商:LINER 制造商全称:Linear Technology 功能描述:600mA Low VIN Buck Regulator in 3mm × 3mm DFN |
| LTC3409AEDD | 制造商:LINER 制造商全称:Linear Technology 功能描述:600mA Low VIN Buck Regulator in 3mm × 3mm DFN |
| LTC3409AEDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC3409AEDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 0.6A 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:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
发布紧急采购，3分钟左右您将得到回复。