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| 型号： | A8510GECTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 28/33页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR BCKLGHT/WHT 26QFN-EC |
| 标准包装： | 1 |
| 拓扑： | PWM，升压（升压） |
| 输出数： | 8 |
| 内部驱动器： | 是 |
| 类型 - 主要： | 背光 |
| 类型 - 次要： | 白色 LED |
| 频率： | 600kHz ~ 2.25MHz |
| 电源电压： | 5 V ~ 40 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 26-WFQFN 裸露焊盘 |
| 供应商设备封装： | 26-QFN/MLP-EP（4x4） |
| 包装： | 标准包装 |
| 工作温度： | -40°C ~ 105°C |
| 其它名称： | 620-1385-6 |
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A8510
Design Example for SEPIC Configuration
Wide Input Voltage Range, High Efficiency
Fault Tolerant LED Driver
of the A8510 is 720 mV. A constant term, 2 V, is added to give
This section provides a method for selecting component values
margin to the design due to noise and output voltage ripple.
when designing an application using the A8510 in SEPIC (Sin-
gle-Ended Primary-Inductor Converter) circuit. SEPIC topology
has the advantage that it can generate a positive output voltage
either higher or lower than the input voltage. The resulting design
is diagrammed in figure 31.
V OUT(OVP) = # SERIESLEDS × V f + V LED + 2 (V)
= 4 × 3.3 (V) + 0.680 (V) + 2 (V) = 15.9 V
Then the OVP resistor is:
R OVP = ( V OUT(OVP) – V OVP(th) ) / I OVPH
(30)
(31)
Assumptions: For the purposes of this example, the following are
given as the application requirements:
? V BAT : 6 to 14 V ( V IN (min): 5 V and V IN (max): 16 V )
? Quantity of LED channels, # CHANNELS : 8
? Quantity of series LEDs per channel, # SERIESLEDS : 4
? LED current per channel, I LED : 40 mA
? LED V f at 60 mA: ≈ 3.3 V
? f SW : 800 kHz
= (15.9 (V) – 8.1 (V)) / 0.199 (mA) = 39.196 k Ω
where both I OVPH and V OVP(th) are taken from the Electrical
Characteristics table.
In this case a value of 39.2 k Ω was selected. Below is the actual
value of the minimum OVP trip level with the selected resistor:
V OUT(OVP) = 39.2 (k Ω ) × 0.199 (mA) + 8.1 (V) = 15.9 V
Step 3b At this point a quick check must be done to determine if
the conversion ratio is acceptable for the selected frequency.
? T A (max): 65°C
? PWM dimming frequency: 200 Hz, 1% duty cycle
D max = 1 – t SWOFFTIME × f SW
= 1 – 1.5 × 47 (ns) × 800 (kHz) = 94.4%
(32)
Procedure: The procedure consists of selecting the appropriate
configuration and then the individual component values, in an
ordered sequence.
Step 1 Connecting LEDs to LEDx pins. If only some of the LED
where the minimum off-time (t SWOFFTIME ) is found in the Electri-
cal Characteristics table.
The Theoretical Maximum V OUT is then calculated as:
channels are needed, the unused LEDx pins should be pulled to
ground using a 1.5 k Ω resistor.
V OUT (max) = V IN (min)
D max
1 – D max
– V d
(33)
Step 2 Determining the LED current setting resistor R ISET :
R ISET = ( V ISET × A ISET ) / I LED
(29)
= 5 (V)
0.94
1 – 0.94
– 0.4 (V) = 77.9 V
= (1.003 (V) × 327) / 0.40 (A) = 8.20 k Ω
Choose an 8.25 k Ω 1% resistor.
Step 3 Determining the OVP resistor. The OVP resistor is
connected between the OVP pin and the output voltage of the
converter.
Step 3a The first step is determining the maximum voltage
based on the LED requirements. The regulation voltage, V LED ,
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, it may be necessary
to reduce the frequency to allow the boost to convert the volt-
age ratios.
Step 4 Selecting the inductor. The inductor must be chosen such
that it can handle the necessary input current. In most applica-
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
28
相关PDF资料 |
PDF描述 |
|---|---|
| A8511KLPTR-T | IC LED DVR 150MA AUTO 28-TSSOP |
| A8512ELBTR-T | IC LED DVR WHT/RGB BKLGT 24SOIC |
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| A8514KLPTR-T | IC LED DVR WHT 4X80MA 16-ETSSOP |
| A8515GLPTR-T | IC LED DVR WHT/RGB BKLGT 16TSSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| A8511 | 制造商:ROCKWE 功能描述: |
| A8511KLPTR-T | 功能描述:IC LED DVR 150MA AUTO 28-TSSOP 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 |
| A8512 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:LED Backlight Driver for Medium/Large Displays |
| A8512EETTR-T | 功能描述:IC LED DVR WHT/RGB BKLGT 28QFN 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 |
| A8512ELBTR-T | 功能描述:IC LED DVR WHT/RGB BKLGT 24SOIC 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 |
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