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| 型号： | A6266KLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 14/17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
Recommended inductor manufacturers/series are:
? Coilcraft/ MSS1278T
? TDK/ SLF12575 type H
Diode The diode should have a low forward voltage, to reduce
conduction losses, and a low capacitance, to reduce switching
losses. Schottky diodes can provide both these features if care-
fully selected. The forward voltage drop is a natural advantage
for Schottky diodes and reduces as the current rating increases.
However, as the current rating increases, the diode capacitance
also increases so the optimum selection is usually the lowest cur-
rent rating above the required maximum, in this case I L(PK) .
Switch Current Sense Resistor (RSS) Neither the absolute
value of the switch current nor the accuracy of the measurement
is important, because the regulator will continuously adjust the
switch current, within a closed loop, to provide sufficient energy
for the output. For maximum accuracy the switch sense resistor
value should be chosen to maximize the differential signal seen
by the sense amplifier. The input limit of the sense amplifier,
V IDS , and the maximum switch current, I S (max), therefore define
the maximum value of the sense resistor as:
R SS = V IDS / I S (max) (18)
Where I S (max) is the maximum switch current and should be set
above the maximum inductor current, I L(PK) .
This represents the maximum measurable value of the switch
(and inductor) current; however, the peak switch current will
always be less than this, set by the control circuit, depending on
the input voltage and the required load conditions. Because the
switch current control is within a closed loop, it is possible to
reduce the value of the sense resistor to reduce its power dissipa-
tion. However this will reduce the accuracy of the regulated LED
current.
The power loss in the switch sense resistor is worse at the lowest
input voltage:
P LOSS = ( V LED [ V LED – V IN (min)] / V IN (min) 2 ) × R SS × I 2LED (19)
External Switch MOSFET A logic-level N-channel MOSFET
is used as the switch for the DC-to-DC converter. The voltage at
the drain of the MOSFET is equal to the maximum voltage across
the string of LEDs.
The peak switch current is defined by the maximum inductor cur-
rent, I L(PK) . However in most cases the MOSFET will be chosen
by selecting low on-resistance, which usually results in a current
rating of several times the required peak current.
In addition to minimizing cost, the choice of MOSFET should
consider both the on-resistance and the total gate charge. The
total gate charge will determine the average current required from
the internal regulator and thus the power dissipation.
Output Capacitor There are several points to consider when
selecting the output capacitor.
Unlike some switch-mode regulators, the value of the output
capacitor in this case is not critical for output stability. The
capacitor value is only limited by the required maximum ripple
voltage.
Due to the switching topology used, the ripple current for this
circuit is high because the output capacitor provides the LED
current when the switch is active. The capacitor is then recharged
each time the inductor passes energy to the output. The ripple
current on the output capacitor will be equal to the peak inductor
current.
Normally this large ripple current, in conjunction with the
requirement for a larger capacitance value for stability, would
dictate the use of large electrolytic capacitors. However in this
case stability is not a consideration, and the capacitor value can
be low, allowing the use of ceramic capacitors.
To minimize self-heating effects and voltage ripple, the equiva-
lent series resistance (ESR), and the equivalent series inductance
(ESL) should be kept as low as possible. This can be achieved by
multilayer ceramic chip (MLCC) capacitors. To reduce perfor-
mance variation over temperature, low drift types such as X7R
and X5R should be used.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
14
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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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