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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)： | 10/20頁 |
| 文件大?。?/td> | 839K |
| 代理商： | LT3486EFE |
LT3486
10
3486f
Figure 5. Timing Resistor (R
T
) Value
Operating Frequency Selection
The choice of operating frequency is determined by sev-
eral factors. There is a tradeoff between efficiency and
component size. Higher switching frequency allows the
use of smaller inductors albeit at the cost of increased
switching losses and decreased efficiency.
Another consideration is the maximum duty cycle
achievable. In certain applications the converter needs to
operate at the maximum duty cycle in order to light up
the maximum number of LEDs. The LT3486 has a fixed
oscillator off-time and a variable on-time. As a result, the
maximum duty cycle increases as the switching frequency
is decreased.
The circuit of Figure 6a is operated with different values of
timing resistor (R
T
). R
T
is chosen so as to run the converters
at 800kHz (R
T
= 63.4k), 1.25MHz (R
T
= 39.1k) and 2MHz
(R
T
= 21.5k). The CTRL pins are used to provide dimming
for the respective LED strings. The efficiency comparison
for different R
T
values is shown in Figure 6b.
APPLICATIU
Duty Cycle
The duty cycle for a step-up converter is given by:
V
V
V
V
V
V
OUT
D
CESAT
+
–
W
U
U
Figure 6a. 5V to 8/8 White LEDs
where:
V
OUT
= Output voltage
V
D
= Schottky forward voltage drop
V
CESAT
= Saturation voltage of the switch
V
IN
= Input battery voltage
The maximum duty cycle achievable for LT3486 is 96%
(typ) when running at 1MHz switching frequency. It in-
creases to 98% (typ) when run at 200kHz and drops to
90% (typ) at 2MHz. Always ensure that the converter is
not duty-cycle limited when powering the LEDs at a given
switching frequency.
D
OUT
D
IN
=
+
–
Setting the Switching Frequency
The LT3486 uses a constant frequency architecture that
can be programmed over a 200kHz to 2MHz range with a
single external timing resistor from the R
T
pin to ground.
The nominal voltage on the R
T
pin is 0.54V, and the
current that flows into the timing resistor is used to charge
and discharge an internal oscillator capacitor. A graph for
selecting the value of R
T
for a given operating frequency
is shown in the Figure 5.
REF
1.25V
25mA
25mA
OFF ON
8.06
8.06
V
C1
V
C2
R
T
R
T
2.8k
2.8k
CIN: 10V, X7R
C
, C
: 35V, X5R
D1, D2: ZETEX ZHCS400
L1, L2: TOKO D53LC TYPE A
4.7nF
4.7nF
SW1
SW2
V
IN
5V
D1
D2
L1
10
μ
H
L2
10
μ
H
C
IN
10
μ
F
C
REF
0.1
μ
F
C
OUT1
2.2
F
C
OUT2
2.2
F
LT3486
3486 F06a
OVP2
CTRL2
REF
PWM2
FB2
OVP1
CTRL1
SHDN
PWM1
FB1
OSCILLATOR FREQUENCY (kHz)
R
T
)
1000
3486 G09
10
100
500
2500
2000
1500
1000
0
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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:- 標準包裝:60 系列:- 恒定電流:- 恒定電壓:- 拓撲: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:- 標準包裝:6,000 系列:- 恒定電流:- 恒定電壓:- 拓撲: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:- 標準包裝:6,000 系列:- 恒定電流:- 恒定電壓:- 拓撲: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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