參數(shù)資料
型號(hào)： LT3486EDHC
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： 5 X 3 MM, 0.75 MM HEIGHT, PLASTIC, MO-229WJED-1, DFN-16
文件頁(yè)數(shù)： 8/20頁(yè)
文件大小： 839K
代理商： LT3486EDHC
LT3486
8
3486f
OPERATIOU
Main Control Loop
The LT3486 uses a constant frequency, current mode
control scheme to provide excellent line and load regulation.
It incorporates two identical, but fully independent PWM
converters. Operation can be best understood by referring
to the block diagram in Figure 1. The oscillator, start-up
bias and the bandgap reference are shared between the two
converters. The control circuitry, power switch, dimming
control etc., are all identical for both converters.
At power-up, the output capacitors of both converters are
charged up to V
IN
(input supply voltage) via their respective
inductor and the Schottky diode. If the SHDN pin is taken
above 1.6V, the bandgap reference, start-up bias and the
oscillator are turned on. Grounding the SHDN pin shuts
down the part.
The CTRL1 and CTRL2 pins perform independent dimming
and shutdown control for the two converters. Taking
the CTRL pins high, enables the respective converters.
Connecting these pins to ground, shuts down each
converter by pulling their respective V
C
pin low.
Working of the main control loop can be understood by
following the operation of converter 1. At the start of
each oscillator cycle, the power switch Q1 is turned on.
A voltage proportional to the switch current is added to
a stabilizing ramp and the resulting sum is fed into the
positive terminal of the PWM comparator A2. When this
voltage exceeds the level at the negative input of A2, the
PWM logic turns off the power switch. The level at the
negative input of A2 is set by the error amplifier A1, and
is simply an amplified version of the difference between
the feedback voltage and the 200mV reference voltage. In
this manner, the error amplifier A1 regulates the feedback
voltage to 200mV reference voltage. The output of the
error amplifier A1 sets the correct peak current level in
inductor L1 to keep the output in regulation. The CTRL1
pin voltage is used to adjust the reference voltage.
The PWM1, 2 control pins are used to extend the dimming
range for the individual converter. The LED current in each
string can be controlled down to μA levels by feeding
a PWM signal to these pins. Refer to the Applications
Information section for more detail.
If only one of the converters is turned on, the other converter
will stay off and its output will remain charged up to V
IN
(input supply voltage).
Minimum Output Current
The LT3486 can drive an 8-LED string at 4mA LED current
without pulse skipping. As current is further reduced, the
device may begin skipping pulses. This will result in some
low frequency ripple, although the LED current remains
regulated on an average basis down to zero. The photo
in Figure 2 shows circuit operation with 8 white LEDs
at 4mA current driven from 3.6V supply. Peak inductor
current is less than 200mA and the regulator operates in
discontinuous mode implying that the inductor current
reached zero during the discharge phase. After the inductor
current reaches zero, the switch pin exhibits ringing due to
the LC tank circuit formed by the inductor in combination
with switch and diode capacitance. This ringing is not
harmful; far less spectral energy is contained in the ringing
than in the switch transitions. The ringing can be damped
by application of a 300
Ω
resistor across the inductors,
although this will degrade efficiency.
Figure 2. Switching Waveforms
V
10mV/DIV
V
20V/DIV
I
L2
200mA/DIV
0.5
μ
s/DIV
3486 F02
V
IN
= 3.6V
I
= 4mA (8 LEDs)
CIRCUIT OF FRONT PAGE APPLICATION
Open-Circuit Protection
The LT3486 has internal open-circuit protection for both
the converters. Connect the overvoltage protection pins
(OVP1, OVP2) to the output of the respective converter.
When the LEDs are disconnected from the circuit or fail
open, the on-chip voltage detectors monitor the voltages at
the OVP1 and OVP2 pins and limits these voltages to 36V
(typ) by turning off the respective switcher. The converter
will then switch at a very low frequency to minimize the
input current. Output voltage and input current during
相關(guān)PDF資料
PDF描述
LT3486EFE Dual 1.3A White LED Step-Up Converters with Wide Dimming
LT3524 Regulating Pulse Width Modulator
LT3524N Regulating Pulse Width Modulator
LT1524 Regulating Pulse Width Modulator
LT1524J Regulating Pulse Width Modulator
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT3486EDHC#PBF 功能描述:IC LED DRIVR WHITE BCKLGT 16-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動(dòng)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(dòng)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
LT3486EDHC#TRPBF 功能描述:IC LED DRIVR WHITE BCKLGT 16-DFN RoHS:是 類別:集成電路 (IC) >> PMIC - LED 驅(qū)動(dòng)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(dòng)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
LT3486EFE 制造商:Linear Technology 功能描述:LED DRVR 16Segment 3.3V/5V/9V/12V/15V/18V 16-Pin TSSOP EP
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(dòng)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(dòng)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(dòng)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(dòng)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
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*