- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358829 > LM2794 (National Semiconductor Corporation) Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control PDF資料下載
參數(shù)資料
| 型號(hào)： | LM2794 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Current Regulated Switched Capacitor LED Supply with Analog and PWM Brightness Control |
| 中文描述： | 電流調(diào)節(jié)開關(guān)電容LED電源與模擬和PWM亮度控制 |
| 文件頁(yè)數(shù)： | 14/16頁(yè) |
| 文件大?。?/td> | 487K |
| 代理商： | LM2794 |
第1頁(yè)第2頁(yè)第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)第7頁(yè)第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)當(dāng)前第14頁(yè)第15頁(yè)第16頁(yè)
Application Information
(Continued)
E = (P
LED
÷ P
IN
)
Efficiency, as defined here, is in part dependent on LED
voltage. Variation in LED voltage does not affect power
consumed by the circuit and typically does not relate to the
brightness of the LED. For an advanced analysis, it is rec-
ommended that power consumed by the circuit (V
x I
) be
evaluated rather than power efficiency.
Figure 7
shows the
power consumption of the LM2794/5 Typical Application Cir-
cuit.
POWER DISSIPATION
The power dissipation (P
DISSIPATION
) and junction tempera-
ture (T
J
) can be approximated with the equations below. P
IN
is the power generated by the 1.5x charge pump, P
LED
is the
power consumed by the LEDs, P
POUT
is the power provided
through the P
OUT
pin, T
A
is the ambient temperature, and
θ
JA
is the junction-to-ambient thermal resistance for the micro
SMD-14 package. V
IN
is the input voltage to the LM2794/5,
V
is the LED forward voltage, I
is the programmed LED
current, and I
POUT
is the current drawn through P
OUT
.
P
DISSIPATION
= P
IN
- P
LED
P
POUT
= [1.5xV
IN
x(4I
DX
+ I
POUT
)] (V
DX
x4I
DX
) (1.5xV
IN
xI
POUT
)
T
J
= T
A
+ (P
DISSIPATION
x
θ
JA
)
The junction temperature rating takes precedence over the
ambient temperature rating. The LM2794/5 may be operated
outside the ambient temperature rating, so long as the junc-
tion temperature of the device does not exceed the maxi-
mum operating rating of 100C. The maximum ambient tem-
perature rating must be derated in applications where high
power dissipation and/or poor thermal resistance causes the
junction temperature to exceed 100C.
MICRO SMD MOUNTING
The LM2794/5 is a 14-bump micro SMD with a bump size of
300 micron diameter. The micro SMD package requires
specific mounting techniques detailed in National Semicon-
ductorApplication Note (AN -1112). NSMD (non-solder mask
defined) layout pattern is recommended over the SMD (sol-
der mask defined) since the NSMD requires larger solder
mask openings over the pad size as opposed to the SMD.
This reduces stress on the PCB and prevents possible
cracking at the solder joint. For best results during assembly,
alignment ordinals on the PC board should be used to
facilitate placement of the micro SMD device. Micro SMD is
a wafer level chip size package, which means the dimen-
sions of the package are equal to the die size. As such, the
micro SMD package lacks the plastic encapsulation charac-
teristics of the larger devices and is sensitive to direct expo-
sure to light sources such as infrared, halogen, and sun light.
The wavelengths of these light sources may cause unpre-
dictable operation.
20028537
FIGURE 6. Efficiency vs V
IN
4 LEDs, V
LED
= 3.6V, I
LED
= 15mA
20028538
FIGURE 7. P
vs V
IN
4 LEDs, 2.5
≤
V
DX
≤
3.9V, I
DX
= 15mA
L
www.national.com
14
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM27952 | White LED Adaptive 1.5X/1X Switched Capacitor Current Driver |
| LM27952SD | White LED Adaptive 1.5X/1X Switched Capacitor Current Driver |
| LM27952SDX | White LED Adaptive 1.5X/1X Switched Capacitor Current Driver |
| LM27961 | Dual-Display White LED Driver with 3/2x Switched Capacitor Boost |
| LM27961TL | Dual-Display White LED Driver with 3/2x Switched Capacitor Boost |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2794BL | 功能描述:IC LED DRVR WHT BCKLT 14USMD RoHS:否 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動(dòng)器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?PWM，切換式電容器（充電泵） 輸出數(shù):1 內(nèi)部驅(qū)動(dòng)器:是 類型 - 主要:背光 類型 - 次要:白色 LED 頻率:642kHz 電源電壓:2.7 V ~ 5.5 V 輸出電壓:5V 安裝類型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:10-VSON 包裝:剪切帶 (CT) 工作溫度:-30°C ~ 85°C 產(chǎn)品目錄頁(yè)面:1371 (CN2011-ZH PDF) 其它名稱:BD1603NUV-E2CT |
| LM2794BL NOPB | 制造商:Texas Instruments 功能描述:LED DRVR 4Segment 3.3V/5V 14-Pin uSMD T/R |
| LM2794BLX | 制造商:Texas Instruments 功能描述: |
| LM2794EVAL | 功能描述:電源管理IC開發(fā)工具 EVAL KIT FOR LM2794 RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM2794TL | 功能描述:IC LED DRVR WHT BCKLT 14MICROSMD RoHS:否 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動(dòng)器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?升壓（升壓），切換式電容器（充電泵） 輸出數(shù):1 內(nèi)部驅(qū)動(dòng)器:是 類型 - 主要:背光 類型 - 次要:白色 LED 頻率:625kHz ~ 875kHz 電源電壓:2.7 V ~ 5.3 V 輸出電壓:5V 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:10-µMAX 包裝:帶卷 (TR) 工作溫度:-40°C ~ 85°C |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。