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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)： | 9/20頁 |
| 文件大小： | 839K |
| 代理商： | LT3486EFE |
LT3486
9
3486f
output open circuit are shown in the Typical Performance
Characteristics graphs.
Figure 3a shows the transient response of switcher 1 with
the LEDs disconnected from the output. When the LED1
string is disconnected from the output, the voltage at
the feedback pin (FB1) drops to 0V. As a result, the error
amplifier charges up the V
C
node to the clamp voltage
level of 1.5V (typ). The converter starts switching at peak
current limit and ramps up the output voltage. When the
output voltage reaches the OVP clamp voltage level of
36V (typ), the LT3486 shuts off the converter by pulling
the V
C
node to ground. The converter then regulates the
output voltage at 36V (typ) by switching at a very low
frequency.
In the event one of the converters has an output open-
circuit, its output voltage will be clamped at 36V (typ).
However, the other converter will continue functioning
properly. The photo in Figure 3b shows circuit operation
with converter 1 output open-circuit and converter 2 driving
eight LEDs at 25mA. Converter 1 starts switching at a very
low frequency, reducing its input current.
Soft-Start
The LT3486 has a separate internal soft-start circuitry for
each converter. Soft-start helps to limit the inrush current
during start-up. Soft-start is achieved by clamping the
output of the error amplifier during the soft-start period.
This limits the peak inductor current and ramps up the
output voltage in a controlled manner.
The converter enters into soft-start mode whenever the
respective CTRL pin is pulled from low to high. Figure 4
shows the start-up waveforms with converter 2 driving
eight LEDs at 25mA. The filtered input current, as shown
in Figure 4, is well controlled. The soft-start circuit is more
effective when driving a smaller number of LEDs.
Undervoltage Lockout
The LT3486 has an undervoltage lockout circuit which
shuts down both the converters when the input voltage
drops below 2.1V (typ). This prevents the converter to
operate in an erratic mode when powered from low supply
voltages.
Overtemperature Protection
The maximum allowable junction temperature for LT3486 is
125°C. In normal operation, the IC’s junction temperature
should be kept below 125°C at an ambient temperature of
85°C or less. If the junction temperature exceeds 150°C, the
internal thermal shutdown circuitry kicks in and turns-off
both the converters. The converters will remain off until
the die temperature falls below 150°C.
OPERATIOU
V
20V/DIV
V
C1
2V/DIV
I
L1
1A/DIV
100
μ
s/DIV
LED1 DISCONNECTED
AT THIS INSTANT
3486 F03a
V
= 3.6V
CIRCUIT OF
FRONT PAGE
APPLICATION
V
1V/DIV
AC COUPLED
I
L1
1A/DIV
I
L2
500mA/DIV
2ms/DIV
3486 F03b
V
IN
= 3.6V
CIRCUIT OF FRONT PAGE APPLICATION
LED1 DISCONNECTED
Figure 3b. Switching Waveforms with Output 1 Open Circuit
V
10V/DIV
V
200mV/DIV
I
IN
200mA/DIV
CTRL2
5V/DIV
0.5ms/DIV
3486 F04
V
IN
= 3.6V
8 LEDs, 25mA
CIRCUIT OF FRONT PAGE APPLICATION
Figure 3a. Transient Response of Switcher 1 with LED1
Disconnected from the Output
Figure 4. Start-Up Waveforms
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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(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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