- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358845 > LM3502SQX-25 (NATIONAL SEMICONDUCTOR CORP) Step-Up Converter for White LED Applications PDF資料下載
參數(shù)資料
| 型號： | LM3502SQX-25 |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 顯示驅(qū)動器 |
| 英文描述： | Step-Up Converter for White LED Applications |
| 中文描述： | LED DISPLAY DRIVER, QCC16 |
| 封裝： | 1MM HEIGHT, LLP-16 |
| 文件頁數(shù)： | 14/18頁 |
| 文件大?。?/td> | 928K |
| 代理商： | LM3502SQX-25 |
Application Information
(Continued)
CONTINUOUS AND DISCONTINUOUS MODES OF
OPERATION
Since the LM3502 is a constant frequency pulse-width-
modulated step-up regulator, care must be taken to make
sure the maximum duty cycle specification is not violated.
The duty cycle equation depends on which mode of opera-
tion the LM3502 is in. The two operational modes of the
LM3502 are continuous conduction mode (CCM) and dis-
continuous conduction mode (DCM). Continuous conduction
mode refers to the mode of operation where during the
switching cycle, the inductor current never goes to and stays
at zero for any significant amount of time during the switch-
ing cycle. Discontinuous conduction mode refers to the
mode of operation where during the switching cycle, the
inductor current goes to and stays at zero for a significant
amount of time during the switching cycle.
Figure 6
illus-
trates the threshold between CCM and DCM operation. In
Figure 6
, the inductor current is right on the CCM/DCM
operational threshold. Using this as a reference, a factor can
be introduced to calculate when a particular application is in
CCM or DCM operation. R is a CCM/DCM factor we can use
to compute which mode of operation a particular application
is in. If R is
≥
1, then the application is operating in CCM.
Conversely, if R is
<
1, the application is operating in DCM.
The R factor inequalities are a result of the components that
make up the R factor. From
Figure 6
, the R factor is equal to
the average inductor current, I
(avg), divided by half the
inductor ripple current,
i
. Using
Figure 6
the following
equation can be used to compute R factor:
20131737
20131738
20131739
20131740
V
IN
:
V
OUT
:
Eff:
Fs:
I
:
L:
D:
i
L
:
I
L
(avg): Average Inductor Current
For CCM operation, the duty cycle can be computed with:
Input Voltage.
Output Voltage.
Efficiency of the LM3502.
Switching Frequency.
White LED Current/Load Current.
Inductance Magnitude/Inductor Value.
Duty Cycle for CCM Operation.
Inductor Ripple Current
20131741
20131742
D:
V
OUT
: Output Voltage.
V
IN
:
Input Voltage.
For DCM operation, the duty cycle can be computed with:
Duty Cycle for CCM Operation.
20131743
20131736
FIGURE 6. Inductor Current Waveform
L
www.national.com
14
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM3502ITL-35 | GT 4C 4#16S SKT PLUG RTANG |
| LM3502ITL-44 | GT 5C 5#16S PIN PLUG |
| LM3502ITLX-25 | Step-Up Converter for White LED Applications |
| LM3502ITLX-16 | Step-Up Converter for White LED Applications |
| LM3502ITL-25 | Circular Connector; MIL SPEC:MIL-C-5015; Body Material:Metal; Series:GT; No. of Contacts:55; Connector Shell Size:32; Connecting Termination:Crimp; Circular Shell Style:Right Angle Plug; Body Style:Right Angle |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3502SQX-25/NOPB | 功能描述:LED照明驅(qū)動器 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 |
| LM3502SQX-35 | 功能描述:LED照明驅(qū)動器 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 |
| LM3502SQX-35/NOPB | 功能描述:LED照明驅(qū)動器 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 |
| LM3502SQX-44 | 功能描述:LED照明驅(qū)動器 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 |
| LM3502SQX-44/NOPB | 功能描述:LED照明驅(qū)動器 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 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。