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参数资料
| 型号： | A6268KLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 17/19页 |
| 文件大小： | 0K |
| 描述： | IC LED CTLR AUTOMOBILE 16TSSOP |
| 标准包装： | 1 |
| 恒定电流： | 是 |
| 拓扑： | 低端，PWM，SEPIC，降压（降压），升压（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： | 标准包装 |
| 工作温度： | -40°C ~ 150°C |
| 其它名称： | 620-1473-6 |
A6268
Automotive High Current LED Controller
MOSFET should therefore be rated at greater than 100 V.
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.
When the input voltage, V IN , reduces below the 5 V regulator
drop out level, the gate drive voltage will correspondingly reduce.
The level that this occurs at will depend on the average cur-
rent required for the gate charge. This level will typically occur
with an input voltage of around 5.3 V. The effect of a reduced
gate drive voltage may be an increase in the on-resistance of the
switching MOSFET.
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.
VBAT
To VIN
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.
The value of the output capacitor will typically be about 10 μ F
and it should be rated above the maximum voltage defined by the
series output LEDs.
Reverse Supply Protection Protection for the A6268 is
provided by an external low current diode between the supply
and the VIN pin, as shown in the Functional Block Diagrams
section. The isolation MOSFET shown in figure 3 is only able to
provide isolation when the supply polarity is correct. However,
with an additional P-channel MOSFET, it is also possible to
provide reverse battery protection to the switching elements and
the LEDs. The additional FET should be connected, as shown in
figure 4, with the drain to the supply and the source to the source
connection of the original isolation MOSFET.
In the complete circuit, consideration should be given to limiting
the maximum gate-source voltage of the FET. If the supply volt-
age is likely to exceed 20 V, then either: a Zener clamp must be
added in parallel with the gate-source resistor to prevent damage
to the FET, or a second resistor added as shown in figure 3.
To FF1
Figure 4. Example of a supply isolation MOSFET
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
17
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| A6271KLPTR-T | 功能描述:LED Driver IC 1 Output DC DC Controller SEPIC, Step-Down (Buck), Step-Up (Boost) Analog, Internal or External PWM Dimming 16-eTSSOP 制造商:allegro microsystems, llc 系列:汽车级，AEC-Q100 包装:剪切带（CT） 零件状态:有效 类型:DC DC 控制器 拓扑:SEPIC，降压（降压），升压（升压） 内部开关:无 输出数:1 电压 - 供电（最低）:4.2V 电压 -?供电（最高）:50V 电压 - 输出:- 电流 - 输出/通道:- 频率:700kHz 调光:模拟，PWM 应用:汽车级 工作温度:-40°C ~ 150°C（TJ） 安装类型:表面贴装 封装/外壳:16-TSSOP（0.173"，4.40mm 宽）裸焊盘 供应商器件封装:16-eTSSOP 标准包装:1 |
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