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參數(shù)資料
| 型號(hào)： | LM2750 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Low Noise, 5.0V Regulated Switched Capacitor Voltage Converter |
| 中文描述： | 低噪聲和5.0V穩(wěn)壓開關(guān)電容電壓轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 13/15頁(yè) |
| 文件大?。?/td> | 370K |
| 代理商： | LM2750 |
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LM2750 LED Drive Application
The LM2750 is an excellent part for driving white and blue
LEDs for display backlighting and other general-purpose
lighting functions. The circuits of
Figure 5
and
Figure 6
show
LED driver circuits for the LM2750-5.0 and the LM2750-ADJ,
respectively. Simply placing a resistor (R) in series with each
LED sets the current through the LEDs:
I
LED
= (V
OUT
- V
LED
) / R
In the equation above, I
LED
is the current that flows through
a particular LED, and V
is the forward voltage of the LED
at the given current. As can be seen in the equation above,
LED current will vary with changes in LED forward voltage
(V
). Mismatch of LED currents will result in brightness
mismatch from one LED to the next.
The feedback pin of the LM2750-ADJ can be utilized to help
better control brightness levels and negate the effects of
LED forward voltage variation. As shown in
Figure 6
, con-
necting the feedback pin to the primary LED-resistor junction
(LED1-R1) regulates the current through that LED. The volt-
age across the primary resistor (R1) is the feedback pin
voltage (1.23V typ.), and the current through the LED is the
current through that resistor. Current through all other LEDs
(LEDx) will not be regulated, however, and will vary with LED
forward voltage variations. When using the LM2750-ADJ in
current-mode, LED currents can be calculated with the
equations below:
I
LED1
= 1.23V / R1
I
LEDx
= (1.23V + V
LED1
- V
LEDx
) / Rx
The current-mode configuration does not improve brightness
matching from one LED to another in a single circuit, but will
keep currents similar from one circuit to the next. For ex-
ample: if there is forward voltage mismatch from LED1 to
LED2 on a single board, the current-mode LM2750-ADJ
solution provides no benefit. But if the forward voltage of
LED1 on one board is different than the forward voltage of
LED1 on another board, the currents through LED1 in both
phones will match. THis helps keep LED currents fairly
consistent from one product to the next, adn helps to offset
lot-to-lot variation of LED forward voltage characteristics.
20035124
FIGURE 5. LM2750-5.0 LED Drive Application Circuit
20035125
FIGURE 6. LM2750-ADJ LED Drive Application Circuit
L
www.national.com
13
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2750LD-5.0 | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| LM2750LD-5.0/NOPB | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| LM2750LD-5.0/ROHS | 制造商:Texas Instruments 功能描述: |
| LM2750LD-ADJ | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| LM2750LD-ADJ/NOPB | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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