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| 型号： | A8508GLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 8/28页 |
| 文件大小： | 0K |
| 描述： | IC LED DVR WHITE 8X120MA 24TSSOP |
| 标准包装： | 8,000 |
| 拓扑： | PWM，SEPIC，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： | 300kHz ~ 800kHz |
| 电源电压： | 9 V ~ 40 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 供应商设备封装： | 24-TSSOP 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 工作温度： | -40°C ~ 105°C |
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A8508
Wide Input Voltage Range, High Efficiency
8-Channel Fault Tolerant LED Driver
Functional Description
Enabling the IC
The IC turns on when a logic high signal is applied on the EN
pin, and the input voltage present on the VIN pin is greater than
the 8.5 V necessary to clear the UVLO (V UVLOrise ) threshold.
Before the LEDs are enabled, the A8508 driver goes through a
C1
V OUT
system check to determine if there are any possible fault condi-
tions that might prevent the system from functioning correctly.
Powering up: LED pin short-to-GND check
C2
C3
V EN
V LEDa (not used)
After the VIN pin goes above the UVLO threshold, and a high sig-
nal is present on the EN pin, the IC proceeds to check if any LEDx
pins are shorted to GND and/or are not used. Each unused pin
should be connected to GND with a 4.75 k Ω pull-down resistor.
After the voltage threshold on the LEDx pins exceeds 120 mV, a
timer of 1536 clock cycles (2 ms at 800 kHz switching frequency,
see figure 2) is applied during which the A8508 determines the
V LEDb (used)
C4
t
Figure 3. LED detect circuit operation for an LED pin that is not being
used; shows V OUT (ch1, 10 V/div.), V EN (ch2, 5 V/div.), an unused LEDx
with a 4.75 k Ω resistor from this pin to GND, V LEDa (ch3, 500 mV/div.), and
a used LEDx, V LEDb (ch4, 500 mV/div.), t = 2 ms/div.
status of the pins. Any unused pin connected to GND with the
pull-down resistor will be taken out of regulation at this point and
will not contribute to the boost regulation loop (see figure 3). A
typical example is shown in figure 4. When a pin is connected to
A8508
LED1
LED2
LED3
LED4
LED5
A8508
LED1
LED2
LED3
LED4
LED5
GND through a 4.75 k Ω resistor, the voltage on that LEDx pin
during the LED detection period is about 200 mV. This is shown
in figure 2.
GND
LED6
LED7
LED8
4.75 k Ω
GND
LED6
LED7
LED8
If an LEDx pin is shorted to ground such that LEDx pin voltage
is < 100 mV, the A8508 will not proceed with soft start until the
short is removed from the LEDx pin. This prevents the A8508
V OUT
Figure 4. Channel select setup: (left) channel LED8 not used,
(right) using all channels.
V OUT
C1
C1
V EN
C2
V EN
C2
Short removed
LED detection period
C3
V LEDa
V LEDb
LED detection period
C3
C4
V LEDa (with temporary short)
V LEDb (no short)
C4
t
Figure 2. LED detect circuit operation for two connected LEDs at f SW =
800 kHz; shows V OUT (ch1, 10 V/div.), V EN (ch2, 5 V/div.), an LEDx, V LEDa
(ch3, 500 mV/div.), another LEDx, V LEDb (ch4, 500 mV/div.), t = 2 ms/div.
t
Figure 5. LED detect circuit operation: device powers-up after the short
is removed from the LED pin; shows V OUT (ch1, 10 V/div.), V EN (ch2,
5 V/ div.), an LEDx with short, V LEDa (ch3, 500 mV/div.), and an LEDx
without short, V LEDb (ch4, 500 mV/div.), t = 2 ms/div.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
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相关代理商/技术参数 |
参数描述 |
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| A8509 | 制造商:ROCKWE 功能描述: |
| A8509GLPTR-T | 功能描述:IC LED DVR WHITE 4X120MA 24TSSOP 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 |
| A8510 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Wide Input Voltage Range, High Efficiency |
| A8510GECTR-T | 功能描述:IC LED DRVR BCKLGHT/WHT 26QFN-EC 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 |
| A8511 | 制造商:ROCKWE 功能描述: |
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