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參數(shù)資料
| 型號： | LT3486EFE |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Dual 1.3A White LED Step-Up Converters with Wide Dimming |
| 中文描述： | 1.3 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 4.40 MM, PLASTIC, TSSOP-16 |
| 文件頁數(shù)： | 13/20頁 |
| 文件大?。?/td> | 839K |
| 代理商： | LT3486EFE |
LT3486
13
3486f
The LED current can be set by:
I
LED
≈ (200mV/R
FB
), when V
CTRL
> 1.8V
I
LED
≈ (V
CTRL
/5 R
FB
), when V
CTRL
< 1V
Feedback voltage variation versus control voltage is given
in the Typical Performance Characteristics graphs.
(b) Using a Filtered PWM Signal
A variable duty cycle PWM can be used to control the
brightness of the LED string. The PWM signal is filtered
(Figure 7) by an RC network and fed to the CTRL1, CTRL2
pins.
The corner frequency of R1, C1 should be much lower
than the frequency of the PWM signal. R1 needs to be
much smaller than the internal impedance in the CTRL
pins, which is 100k
Ω
.
Pulse-Width Modulation (PWM)
Adjusting the forward current flowing in the LEDs changes
the intensity of the LEDs, as explained in the previous sec-
tion. However, a change in forward current also changes the
color of the LEDs. The chromaticity of the LEDs changes
with the change in forward current. Many applications can-
not tolerate any shift in the color of the LEDs. Controlling
the intensity of the LEDs via applying a PWM signal allows
dimming of the LEDs without changing the color.
Dimming the LEDs via a PWM signal essentially involves
turning the LEDs on and off at the PWM frequency. The
human eye has a limit of 60 frames per second. By in-
creasing the PWM frequency to say, 80Hz, the eye can
be deceived into believing that the pulsed light source is
continously on. Additionally by modulating the duty cycle
(amount of “on-time”), the intensity of the LEDs can be
controlled. The color of the LEDs remains unchanged in
this scheme since the LED current value is either zero or
a constant value.
Figure 8(a) shows a 12V to 8/8 white LED driver. The PWM
dimming control method requires an external NMOS tied
to the cathode of the lowest LED in the string, as shown in
3486 F07
C1
1
μ
F
PWM
10kHz TYP
R1
10k
LT3486
CTRL1,2
Figure 7. Dimming Control Using a Filtered PWM Signal
APPLICATIU
W
U
U
3486 TA10a
12V (TYP)
9V TO 15V
C
OUT1
2.2
F
C
OUT2
2.2
F
100mA
PWM
FREQ
1kHz
R
FB1
2
R
FB2
2
100mA
OFF ON
D1
Q1
100k
100k
3.65k
3.65k
21.5k
Q2
5V
D2
C
IN
10
μ
F
C1 1
μ
F
L1
10
μ
H
L2
10
μ
H
V
IN
V
IN
DIMMING
INPUT 1
DIMMING
INPUT 2
2.2nF
22pF
2.2nF
LUXEON
LEDs
LXCL-PWF1
LUXEON
LEDs
LXCL-PWF1
C
OUT1
, C
OUT2
: 35V, X5R OR X7R
C
: 25V, X5R OR X7R
C1: 10V, X5R OR X7R
C
REF
: 6.3V, X5R OR X7R
C
REF
0.1
μ
F
V
C1
V
C2
R
T
SW1
SW2
OVP2
V
IN
LT3486
CTRL2
REF
PWM2
FB2
OVP1
CTRL1
SHDN
PWM1
FB1
PWM
FREQ
1kHz
D1, D2: ZETEX ZLLS1000
L1, L2: TOKO D53LC (TYPE A)
Q1, Q2: FAIRCHILD FDN5630
I
L
500mA/DIV
I
200mA/DIV
PWM
5V/DIV
0.2ms/DIV
3486 G18
V
= 12V
8/8 LEDs
PWM FREQ = 1kHz
Figure 8a. 12V to 8/8 White LEDs
Figure 8b. PWM Dimming Waveforms
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LT3524 | Regulating Pulse Width Modulator |
| LT3524N | Regulating Pulse Width Modulator |
| LT1524 | Regulating Pulse Width Modulator |
| LT1524J | Regulating Pulse Width Modulator |
| LT3524J | Regulating Pulse Width Modulator |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT3486EFE#PBF | 功能描述:IC LED DRVR WHITE BCKLGT 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動器 系列:- 標(biāo)準(zhǔn)包裝:60 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?線性（LDO），PWM，升壓（升壓） 輸出數(shù):8 內(nèi)部驅(qū)動器:是 類型 - 主要:背光 類型 - 次要:RGB，白色 LED 頻率:500kHz ~ 1.5MHz 電源電壓:4.75 V ~ 26 V 輸出電壓:45V 安裝類型:* 封裝/外殼:* 供應(yīng)商設(shè)備封裝:* 包裝:* 工作溫度:-40°C ~ 85°C |
| LT3486EFE#TRPBF | 功能描述:IC LED DRVR WHITE BCKLGT 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動器 系列:- 標(biāo)準(zhǔn)包裝:6,000 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?開路漏極，PWM 輸出數(shù):4 內(nèi)部驅(qū)動器:是 類型 - 主要:LED 閃爍器 類型 - 次要:- 頻率:400kHz 電源電壓:2.3 V ~ 5.5 V 輸出電壓:- 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:8-HVSON 包裝:帶卷 (TR) 工作溫度:-40°C ~ 85°C 其它名稱:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
| LT3486EFEPBF | 制造商:Linear Technology 功能描述:Dual 1.3A White LED dim driver,LT3486 |
| LT3486IFE#PBF | 功能描述:IC LED DRVR WHITE BCKLGT 16TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動器 系列:- 標(biāo)準(zhǔn)包裝:6,000 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?開路漏極，PWM 輸出數(shù):4 內(nèi)部驅(qū)動器:是 類型 - 主要:LED 閃爍器 類型 - 次要:- 頻率:400kHz 電源電壓:2.3 V ~ 5.5 V 輸出電壓:- 安裝類型:表面貼裝 封裝/外殼:8-VFDFN 裸露焊盤 供應(yīng)商設(shè)備封裝:8-HVSON 包裝:帶卷 (TR) 工作溫度:-40°C ~ 85°C 其它名稱:935286881118PCA9553TK/02-TPCA9553TK/02-T-ND |
| LT3486IFE#PBF | 制造商:Linear Technology 功能描述:LED DRIVER BOOST PWM 1MHZ 制造商:Linear Technology 功能描述:LED DRIVER, BOOST, PWM, 1MHZ, TSSOP-16 |
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