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參數(shù)資料
| 型號： | LM3405A |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT23 Package |
| 中文描述： | 1.6MHz的，第1A恒流降壓型LED在微型SOT23封裝和內(nèi)部補(bǔ)償驅(qū)動(dòng)器 |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 396K |
| 代理商： | LM3405A |
The gate charge loss is associated with the gate charge Q
G
required to drive the switch:
P
G
= f
SW
x V
IN
x Q
G
The power loss required for operation of the internal circuitry:
P
Q
= I
Q
x V
IN
I
is the quiescent operating current, and is typically around
1.8mA for the LM3405A.
The total power loss in the IC is:
P
INTERNAL
= P
COND
+ P
SW
+ P
G
+ P
Q
An example of power losses for a typical application is shown
in
Table 2
:
TABLE 2. Power Loss Tabulation
Conditions
Power loss
V
IN
V
OUT
I
OUT
V
D1
R
DS(ON)
f
SW
T
RISE
T
FALL
I
Q
Q
G
D is calculated to be 0.36
12V
3.9V
1.0A
0.45V
300m
1.6MHz
P
COND
108mW
18ns
P
SW
288mW
12ns
1.8mA
P
Q
P
G
22mW
1.4nC
27mW
Σ (
P
COND
+ P
SW
+ P
Q
+ P
G
) = P
INTERNAL
P
INTERNAL
= 445mW
PCB Layout Considerations
When planning layout there are a few things to consider when
trying to achieve a clean, regulated output. The most impor-
tant consideration when completing the layout is the close
coupling of the GND connections of the input capacitor C1
and the catch diode D1. These ground ends should be close
to one another and be connected to the GND plane with at
least two through-holes. Place these components as close to
the IC as possible. The next consideration is the location of
the GND connection of the output capacitor C2, which should
be near the GND connections of C1 and D1.
There should be a continuous ground plane on the bottom
layer of a two-layer board except under the switching node
island.
The FB pin is a high impedance node and care should be
taken to make the FB trace short to avoid noise pickup that
causes inaccurate regulation. The LED current setting resis-
tor R1 should be placed as close as possible to the IC, with
the GND of R1 placed as close as possible to the GND of the
IC. The V
trace to LED anode should be routed away from
the inductor and any other traces that are switching.
High AC currents flow through the V
, SW and V
traces,
so they should be as short and wide as possible. Radiated
noise can be decreased by choosing a shielded inductor.
The remaining components should also be placed as close
as possible to the IC. Please see Application Note AN-1229
for further considerations and the LM3405A demo board as
an example of a four-layer layout.
www.national.com
12
L
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相關(guān)代理商/技術(shù)參數(shù) |
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| LM3405A_08 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT23 and eMSOP Package |
| LM3405AEVAL | 功能描述:BOARD EVAL FOR LM3405 RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - LED 驅(qū)動(dòng)器 系列:PowerWise® 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® 電流 - 輸出 / 通道:20mA 輸出及類型:1，非隔離 輸出電壓:17V 特點(diǎn):可調(diào)光 輸入電壓:2.7 ~ 5.5 V 已供物品:板 已用 IC / 零件:LM3508 相關(guān)產(chǎn)品:LM3508TLX-ND - IC LED DRVR WHT BCKLGT 9USMDLM3508TLDKR-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLCT-ND - IC LED DRVR WHT BCKLGT 9MICROSMDLM3508TLTR-ND - IC LED DRVR WHT BCKLGT 9MICROSMD |
| LM3405AEVAL/NOPB | 功能描述:LED 照明開發(fā)工具 LM3405A EVAL BOARD RoHS:否 制造商:Fairchild Semiconductor 產(chǎn)品:Evaluation Kits 用于:FL7732 核心: 電源電壓:120V 系列: 封裝: |
| LM3405AXMK | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT23 and eMSOP Package |
| LM3405AXMK/NOPB | 功能描述:LED照明驅(qū)動(dòng)器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N |
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