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參數(shù)資料
| 型號： | SP7612 |
| 元件分類： | LED驅(qū)動器 |
| 英文描述： | Low Dropout LED Driver for any Color LED |
| 中文描述： | 低壓差的LED彩色LED驅(qū)動器的任何 |
| 文件頁數(shù)： | 5/9頁 |
| 文件大?。?/td> | 216K |
| 代理商： | SP7612 |
5
Date: 6/30/04
SP7611A/7612/7614 Low Dropout LED Driver for Any Color LED Copyright 2004 Sipex Corporation
APPLICATION INFORMATION
SETTING THE LED CURRENT
The current flowing into LEDs is approximately 200
times greater than the current I
SET
. The LED current is
controlled by
I
CONTROL
and R
SET
according to the follow-
ing formula
:
I
LED
= 200 X (V
CONTROL
- V
CTRL
)
/ R
SET
For V
CONTROL
= 3V and a specified LED current, the R
SET
value can be evaluated using the diagram shown in the
Typical Performance Characteristics section. For any
other option, I
SET
vs. V
CTRL.
The LED's brightness can
also be adjusted by driving ENABLE or the CTRL pin with
a PWM signal. The driving signal frequency should be
greater than 100Hz to avoid flickering, increasing to
more than 1MHz, if necessary.
LEDs are very sensitive to temperature. In most cases
the maximum allowed junction temperature is 100oC.
This temperature is the result of adding to the ambient
temperature the over temperature due to power dissipa-
tion, is described by the following:
T
j
= T
A
+
jA
x I xV
F
where T
j
is the LED junction temperature, T
A
is the
ambient temperature,
jA
is the junction to ambient
thermal resistance, I is the LED current and V
F
is the LED
forward voltage
.
The SP7611AA to SP7614 are designed to reduce the
current through LEDs, when the temperature rises and
the cathode voltage increases, as can be seen from
typical the "LED Current vs. LED Cathode Voltage"
graph under the Typical Performance Characteristics
section.
The SP761X driver's low dropout architecture can sig-
nificantly mprove the efficiency compared to using simple
ballast resistors.
The system efficiency, defined as the ratio between the
LEDs power and the input supplied power can be
calculated as follows:
Efficiency = (V
IN
- V
CATHODE
)
/ V
IN
The lower the V
CATHODE
, the higher the system effi-
ciency. Efficiency can be further improved using a higher
V
IN
with more LEDs as shown in example 3.
APPLICATION NOTES
The ultra-low voltage drop across the SP761X series of
LED drivers, allow the devices to drive white, blue, and
other color LEDs in a wide range of input voltages. The
driver can be used in many applications. Although, only
the SP7611A is shown in all three examples, any of the
SP762X series of LED drivers can be used in the
applications presented in this document, due to their
similar operation.
Example 1: Drive low V
F
white or blue LEDs directly
from single cell Li-ion
When using white or blue low V
F
LEDs, and utilizing the
drivers low voltage drop, only 3.4V in V
IN
is needed for the
full 20mA LED current. At 3.1V, there is still 5mA typical
current available for the LEDs. The single cell Li-ion is
utilized in most applications like cell phones or digital still
cameras. In most cases, the Li-ion battery voltage level
only goes down to 3.0V voltage level, and not down to the
full discharge level (2.7V) before requesting the charger.
- T
DROP
< 0.3V
- V
F
(at 20mA) < 3.1V (Low V
F
)
- V
IN
(at 20mA) < - V
DROP
+V
F
= 3.4V
- V
IN
(at 5mA typical) ~ 3.1V
Key Advantages
1) No boost circuit needed for the LCD or keyboard
backlight
2) Drivers directly connected to a Li-ion battery
3) No EMI, no switching noise, no boost efficiency lost,
no capacitor, and no inductor
VIN
LED1
GND
CTRL
ON/OFF
ENABLE
VCONTROL
RSET
SP7611
ISET
LED3
LED2
LED4
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SP7612EC6 | Low Dropout LED Driver for any Color LED |
| SP7648 | Low Reference High Efficiency Boost Regulator |
| SP7648ER | Low Reference High Efficiency Boost Regulator |
| SP7648EU | Low Reference High Efficiency Boost Regulator |
| SP7648TR | Low Reference High Efficiency Boost Regulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP7612A | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:2-4 Channel Low Dropout Linear LED Driver |
| SP7612AEC6 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Dropout LED Driver for any Color LED |
| SP7612AEC6/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Low Dropout LED Driver for any Color LED |
| SP7612AEC6-L | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述:LED DRIVER LOW DROPOUT SMD 7612 |
| SP7612AEC6-L/TR | 功能描述:LED照明驅(qū)動器 LOW DROPOUT LED DRVR ANY COLOR W/ A SHUT 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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