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| 型号： | A8509GLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 14/28页 |
| 文件大小： | 0K |
| 描述： | IC LED DVR WHITE 4X120MA 24TSSOP |
| 标准包装： | 8,000 |
| 拓扑： | PWM，SEPIC，升压（升压） |
| 输出数： | 4 |
| 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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A8509
Pulse-by-pulse current limit
Wide Input Voltage Range, High Efficiency
4-Channel Fault Tolerant LED Driver
Secondary boost switch limit
Figure 21 illustrates the normal waveform for the current sense
signal. The pulse-by-pulse current limit is designed to limit the
current through the external MOSFET to prevent failure. When
the V SENSEP threshold is reached, the IC stops switching to allow
the inductor current to fall. Operation of pulse-by-pulse current
In case there is an inductor short during operation ,the A8509 has
a secondary switch current limit. When this threshold is reached,
the IC immediately shuts down. The level of this current limit is
set above the pulse-by-pulse current limit to protect the switch
from destructive currents when the boost inductor is shorted.
limiting is shown in figure 22.
Output overvoltage and undervoltage
protection
I L
The OVP pin on the A8509 controls both the overvoltage (OVP)
and undervoltage (UVP) protection features. The pin circuit is
shown in figure 23. The OVP protection protects the boost con-
verter from excessive voltage levels when the feedback control
C1
V SENSE
Normal spikes
due to switching
loop is broken, usually caused by an open connection from output
voltage to the LEDs. The UVP function provides output voltage-
to-ground short protection when an external disconnect switch is
used. For more detailed information on disconnect switch appli-
cation, see the Undervoltage Protection (UVP) section.
C2
C3
V GATE
t
For proper operation of this pin, due to the relatively low voltage
level, special care has to be taken during PCB layout. Figure 24 is
an example of a proper PCB layout.
Figure 21. Current sense signal (V SENSE ) during normal operation,
showing large spikes that are filtered out by a blanking period to avoid
false overcurrent tripping; R SENSE = 10 m Ω ; shows inductor current I L (ch1,
1 A/div.), V SENSE (ch2, 20 mV/div.), and gate voltage of the main boost
switch V GATE (ch3), t = 500 ns/div.
A8509
OVP
1.25 V
OVP
VOUT
ROVP
–
50 μ A
UVP
+
100 mV
I L
Figure 23. Simplified schematic of the Overvoltage Protection section.
V OUT
A8509LP
OVP
C2
C1
V COMP
ROVP
A
VOUT
C3
C4
V GATE
B
t
Figure 22. Typical pulse-by-pulse current limit; shows I L (ch1, 2 A/div.),
V OUT (ch2, 10 V/div.), V COMP (ch3, 2 V/div.), and V GATE (ch4),
t = 500 ns/div.
Figure 24. Simplified schematic of the OVP resistor connections; (A)
connection should be short, (B) connection to VOUT can be long, and
ROVP should be as close to the OVP pin as possible.
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 |
|---|---|
| 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: |
| 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 |
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