- 您現(xiàn)在的位置：買(mǎi)賣(mài)IC網(wǎng) > PDF目錄375160 > A8430EEK (Allegro MicroSystems, Inc.) White LED Driver Constant Current Step-up Converter PDF資料下載
參數(shù)資料
| 型號(hào)： | A8430EEK |
| 廠商： | Allegro MicroSystems, Inc. |
| 元件分類(lèi)： | LED驅(qū)動(dòng)器 |
| 英文描述： | White LED Driver Constant Current Step-up Converter |
| 中文描述： | 白光LED驅(qū)動(dòng)恒流升壓轉(zhuǎn)換器 |
| 文件頁(yè)數(shù)： | 6/10頁(yè) |
| 文件大?。?/td> | 329K |
| 代理商： | A8430EEK |
6
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
D
2
A8430
White LED Driver Constant Current Step-up Converter
Component Selection
The component values shown in schematic 1 are sufficient
for most applications. To reduce the output ripple the
inductor may be increased, but in most cases this results in
excessive board area and cost.
Inductor Selection
.
With an internal PWM frequency of
1.2 MHz, the optimal inductor value for most cases is 22 μH.
The inductor should have low winding resistance, typically
< 1
, and the core should have low losses when operating
at 1.2 MHz. For worst case conditions, high output voltage
and current and low input voltage, the inductor should be
rated at the switch current limit, I
SWLIM
. If high temperature
operation is required a derating factor will have to be
considered. In some cases, where lower inductor currents
are expected, the current rating can be decreased. Several
inductor manufacturers have and are developing suitable
small-size inductors, including: Murata, Panasonic, Sumida,
Taiyo Yuden, and TDK.
Diode Selection
.
The diode should have a low forward
voltage to reduce conduction losses. In addition, it should
have a low capacitance to reduce switching losses. Schottky
diodes can provide both these features, if carefully
selected. The forward voltage drop is a natural advantage
for Schottky diodes, and it reduces as the current rating
increases. However, as the current rating increases, the
diode capacitance also increases. As a result, the optimal
selection is usually the lowest current rating above the circuit
maximum. With the A8430, a current rating in the range from
100 mA to 200 mA is usually sufficient.
Capacitor Selection
.
Because the capacitor values are
low, ceramic capacitors are the best choice for use with the
A8430. To reduce performance variation as temperature
changes, low drift capacitor types, such as X7R and X5R,
should be used. Suitable capacitors are available from: Taiyo
Yuden, Murata, Kemet, and AVX.
Dimming Control
LED brightness can be controlled either by modifying the
voltage at the top of the sense resistor (R1) to control the
LED current, I
LOAD
, directly, or by using a PWM signal on
the EN pin to chop the output.
Application Information
Schematic 2. Dimming control with dc voltage
feedback modulation
A8430
VIN
SW
EN
GND
FB
Li-ion
2.5V to
4.2V
C1
1μF
L1
22μH
D1
C2
0.22μF
R1
6.3
V
C
R3
90k
R2
5k
Enable
Feedback modulation
.
By adding a voltage drop
between the FB pin and R1 (the sense resistor), as shown
in schematic 2, the LED current, I
LOAD
, can be made to
decrease. As V
C
(control voltage) increases, the voltage drop
across R2 also increases. This causes the voltage at FB to
increase, and the A8430 reduces I
LOAD
to compensate. As V
C
increases further, the current drops to zero, and R2 maintains
the full 95 mV on FB. Reducing V
C
diminishes the voltage
across R2 until, at 95 mV on V
C
, there is no drop across R2
and the current level is defined by R1. Reducing V
C
below
95 mV causes I
LOAD
to increase further, due to the voltage
drop across R2 in the reverse direction. This continues until,
at zero volts on V
C
, there is approximately 5 mV across R2.
At that point, I
LOAD
(mA), is defined as:
I
LOAD
= 100 mV R1
where R1 is the resistance of the sense resister (
).
PWM Control
. LED dimming control can also be generated
by a filtered PWM signal as shown in schematic 3. In this
case, a 0% duty cycle (PWM = 0 V) corresponds to full
brightness and a 100% duty cycle causes the LED current,
I
LOAD
, to go to zero.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| A8430EEK-T | White LED Driver Constant Current Step-up Converter |
| A8431 | White LED Driver Constant Current Step-up Converter |
| A8431EEH-T | White LED Driver Constant Current Step-up Converter |
| A8436 | Photoflash Capacitor Charger with IGBT Driver |
| A8436EEJTR-T | Photoflash Capacitor Charger with IGBT Driver |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| A8430EEK-T | 制造商:ALLEGRO 制造商全稱(chēng):Allegro MicroSystems 功能描述:White LED Driver Constant Current Step-up Converter |
| A8430EEKTR-T | 功能描述:IC LED DRVR WHITE BCKLGHT 5-MLPD RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - LED 驅(qū)動(dòng)器 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 恒定電流:- 恒定電壓:- 拓?fù)?PWM，切換式電容器（充電泵） 輸出數(shù):1 內(nèi)部驅(qū)動(dòng)器:是 類(lèi)型 - 主要:背光 類(lèi)型 - 次要:白色 LED 頻率:642kHz 電源電壓:2.7 V ~ 5.5 V 輸出電壓:5V 安裝類(lèi)型:表面貼裝 封裝/外殼:10-VFDFN 裸露焊盤(pán) 供應(yīng)商設(shè)備封裝:10-VSON 包裝:剪切帶 (CT) 工作溫度:-30°C ~ 85°C 產(chǎn)品目錄頁(yè)面:1371 (CN2011-ZH PDF) 其它名稱(chēng):BD1603NUV-E2CT |
| A8430EEKTR-T | 制造商:Allegro MicroSystems 功能描述:DC-DC Converter IC |
| A8431 | 制造商:ALLEGRO 制造商全稱(chēng):Allegro MicroSystems 功能描述:White LED Driver Constant Current Step-up Converter |
| A8431EEH-T | 制造商:ALLEGRO 制造商全稱(chēng):Allegro MicroSystems 功能描述:White LED Driver Constant Current Step-up Converter |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。