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| 型号： | A8513KLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 18/25页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR AUTO BCKLGHT 16TSSOP |
| 特色产品： | Allegro A8513 LED Driver |
| 标准包装： | 1 |
| 拓扑： | PWM，SEPIC，升压（升压） |
| 输出数： | 1 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 车载，背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 1.8MHz ~ 2.2MHz |
| 电源电压： | 4.5 V ~ 40 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 ~ 125°C |
| 其它名称： | 620-1440-6 |
A8513
Design Example
Wide Input Voltage Range, High Efficiency
Fault Tolerant LED Driver
To find the OVP resistor values, the user should choose a resis-
This section provides a method for selecting component values
when designing an application using the A8513. A typical circuit
using this design is shown in figure 22.
Assumptions: For the purposes of this example, the following are
given as the application requirements:
? V IN : 5 to 16 V
? Quantity of series LEDs, # SERIESLEDS : 6
? LED current, I LED : 120 mA
? V f at 120 mA: 3.2 V
? f SW : 2 MHz
tor divider that has very low current (I OVP ) and R OVP should be
approximately 1 M Ω . A good starting point is 50 μ A as I OVP .
(The I OVP current is used later in calculating the total leakage
current.) Then :
R OVP1 = ( V OUT(OVP) – V OVPHI(th) ) / I OVP (9)
= (22.08 V – 1.218 V) / 50 μ A = 417.2 k Ω
and:
R OVP2 = V OVPHI(th) / I OVP (10)
= 1.218 V / 50 μ A = 24.36 k Ω
Choose a value of resistor that is higher value than the calculated
R OVP . In this case 422 k Ω was selected. Below is the actual value
of the minimum OVP trip level with the selected resistor:
? T A (max): 85°C
V OUT(OVP) = R OVP × I OVP × V OVPHI(th)
(11)
? PWM dimming frequency: 200 Hz with a minimum duty cycle
of 1%.
Procedure: Select the appropriate configuration and the individual
= 422 k Ω × 50 μ A + 1.218 V = 22.32 V
STEP 3b: At this point a quick check should be done to determine
if the conversion ratio is acceptable for the selected frequency:
component values in an ordered sequence.
D maxofboost = 1 – t SW(OFF) × f SW
(12)
Step 1: Connect the series LED string from VOUT to the LED
pin.
Step 2: Determine the value for the I LED setting resistor, R ISET :
= 1 – 85 ns × 2 MHz = 83%
where the Minimum Switch Off-Time, t SW(OFF) , is found in the
Electrical Characteristics table.
R ISET = V ISET × A ISET / I LED
(7)
The Theoretical Maximum V OUT is then calculated as:
= (1.003 × 1045) / 120 mA = 8.74 k Ω
Choose an 8.66 k Ω resistor.
V OUT (max) =
V IN (min)
1 – D maxofboost
– V d
(13)
Step 3: Determine the values of the OVP resistors. The OVP
resistors are connected between the OVP pin and the output volt-
=
5V
1 – 0.83
– 0.4 V = 29.01 V
age (VOUT) and the OVP pin and ground.
Step 3a: The first step is to determine the maximum voltage
based on the LED V f requirements. To this value the regulation
voltage should be added, as well as another 2 V to account for
noise, output ripple, and resistor tolerances. The regulation volt-
age, V LED , of the A8513 is 880 mV. Then:
V OUT(OVP) = # SERIESLEDS × V f + V LED + 2 V (8)
= 6 × 3.2 V+ 0.880 V + 2 V
= 22.08 V
where V d is the diode forward voltage.
The Theoretical Maximum V OUT value must be greater than the
value V OUT(OVP) . If this is not the case, a lower frequency ver-
sion of the A8513 should be chosen to meet the maximum duty
cycle requirements.
Step 4: Inductor selection. The inductor should be chosen such
that it can handle the necessary input current. In most applica-
tions, due to stringent EMI requirements, the system must operate
in continuous conduction mode throughout the whole input volt-
age range.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A8513KLYTR-1-T | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver |
| A8513KLYTR-2-T | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver |
| A8513KLYTR-3-T | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver |
| A8513KLYTR-T | 功能描述:IC LED DRVR AUTO BCKLGHT 10MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - LED 驱动器 系列:- 特色产品:LM3445 TRIAC Dimmable LED Driver 标准包装:55 系列:PowerWise® 恒定电流:是 恒定电压:- 拓扑:PWM，降压（降压） 输出数:1 内部驱动器:无 类型 - 主要:- 类型 - 次要:高亮度 LED（HBLED） 频率:30kHz ~ 1MHz 电源电压:8 V ~ 12 V 输出电压:- 安装类型:表面贴装 封装/外壳:14-SOIC（0.154"，3.90mm 宽） 供应商设备封装:14-SOICN 包装:管件 工作温度:-40°C ~ 125°C 产品目录页面:1285 (CN2011-ZH PDF) 其它名称:LM3445M |
| A8514 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:The A8514 is a multi-output white LED driver for small-size LCD backlighting. |
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