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| 型号： | A6266KLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 13/17页 |
| 文件大小： | 0K |
| 描述： | IC LED CTLR AUTO HI CURR 16TSSOP |
| 标准包装： | 8,000 |
| 恒定电流： | 是 |
| 拓扑： | 低端，PWM，升压 |
| 输出数： | 1 |
| 内部驱动器： | 无 |
| 类型 - 主要： | 车载，背光 |
| 频率： | 100kHz ~ 700kHz |
| 电源电压： | 5 V ~ 50 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 供应商设备封装： | 16-TSSOP-EP |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 150°C |
A6266
Automotive, Boost, High Current LED Controller
Application Information
Component Selection
External component selection is critical to the successful appli-
cation of the LED driver. Although the inductor, the switching
MOSFET, and the output capacitor are the most critical elements,
the specification of the rectifying diode and sense resistors should
also be carefully considered.
Inductor Selection Selecting the correct inductance is a
balance between choosing a value that is small enough to help
reduce size and cost, but high enough to ensure that the inductor
current ripple is kept to an acceptable level. A reasonable target
for the ripple current is 20% of the maximum average current.
The maximum average inductor current is approximately:
The starting point for component selection is to define the maxi-
mum LED current, the voltage across the LEDs, and the input
operating voltage range. This then allows the average inductor
current under worst case conditions to be calculated. The induc-
tor value is then selected based on the acceptable inductor ripple
current. The amount of ripple current will then determine the
I L(av) (max) = I LED (max) × V LED / V IN (min)
The inductor current ripple is approximately:
I LRIP = V IN × ( V LED – V IN ) / ( f OSC × L × V LED )
The inductor value is therefore:
(14)
(15)
maximum inductor current under worst case conditions. From
this current the switch current sense resistor can be calculated.
where:
L = V IN × ( V LED – V IN ) / ( f OSC × I LRIP × V LED ) (16)
LED Current Sense Resistor (R LS ) If the voltage at the
IREF pin, V IREF , is greater than 1V, or if IREF is tied to VREG,
then the value of the LED current sense resistor, R LS , can be
calculated from:
R LS = V IDL / I LED (max) (11)
where V IDL is the differential voltage across the LED current
sense amplifier and I LED (max) is the maximum LED current.
V LED is the voltage across the LED string,
V IN is the supply voltage,
V IN (min) is the minimum supply voltage,
L is the inductor value, and
f OSC is the oscillator frequency.
With an internal oscillator frequency of 350 kHz, the value of
the inductor for most cases will be between 20 and 50 μ H. The
If V IREF is less than 1 V, then the value of the LED current sense
resistor can be calculated from:
maximum inductor current can then be calculated as:
I L(PK) = I L(av) (max) + ( I RIP / 2)
(17)
R LS = V IREF / (10 × I LED (max) )
(12)
This defines the minimum peak switch current as set by the
The typical value for V IDL is 100 mV. Examples of various sense
resistor values are given in table 2.
The power loss in the current sense resistor is worse at the lowest
input voltage:
switch current sense resistor.
The current rating for the inductor should be greater, by some
margin, than the peak value above, I L(PK) . When selecting an
inductor from manufacturers datasheets, there are two current
P LOSS = ( V LED / V IN (min) ) × R LS × I 2LED
(13)
levels usually defined, the smallest value being the figure to work
with:
The resistors should be of a low inductance construction. Surface
mount chip resistors are usually the most suitable, however, axial
or radial leaded resistors can be used provided that the lead length
is kept to a minimum.
Table 2. Sense Resistor Values
I LED (max) R LS
(mA) (m Ω )
350 286
700 143
1000 100
? Saturation level, where the inductance value typically drops by
10%, or
? Temperature rise, where the part experiences a certain rise in
temperature at full rated current. This parameter can be defined
between a 20°C and 50°C rise in temperature. It is important to
understand how manufacturers define the maximum operating
temperature, because this can often incorporate the self-heating
temperature rise.
In most cases the limiting current is usually the saturation value.
To improve efficiency, the inductor should also have low winding
resistance, typically < 50 m Ω , and the core material will usually
be ferrite, with low losses at the oscillator frequency.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A6267 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:The A6267 is a DC-to-DC converter controller, providing a programmable constant current output for driving high power LEDs in series. |
| A6267KLPTR-T | 功能描述:IC LED CTLR AUTO HI CURR 16TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 恒定电流:- 恒定电压:- 拓扑:升压（升压），切换式电容器（充电泵） 输出数:1 内部驱动器:是 类型 - 主要:背光 类型 - 次要:白色 LED 频率:625kHz ~ 875kHz 电源电压:2.7 V ~ 5.3 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-µMAX 包装:带卷 (TR) 工作温度:-40°C ~ 85°C |
| A6268 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:The A6268 is a DC-to-DC converter controller, providing a programmable constant current output for driving high power LEDs in series. |
| A6268KLPTR-T | 功能描述:IC LED CTLR AUTOMOBILE 16TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 恒定电流:- 恒定电压:- 拓扑:升压（升压），切换式电容器（充电泵） 输出数:1 内部驱动器:是 类型 - 主要:背光 类型 - 次要:白色 LED 频率:625kHz ~ 875kHz 电源电压:2.7 V ~ 5.3 V 输出电压:5V 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-µMAX 包装:带卷 (TR) 工作温度:-40°C ~ 85°C |
| A6269 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Automotive LED Array Driver |
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