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| 型号： | A8508GLPTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 11/28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
indicated by the specifications for t PWSYNCON and t PWSYNCOFF .
Thus any pulse with a duty cycle of 19% to 85% at 800 kHz will
f SW = 800 kHz from
RFSET value
Changeover
period
f SW = 600 kHz
from SYNC pulse
synchronize the IC.
It is recommended to also use the RFSET resistor with the
external clock signal. If a synchronization clock is lost during
operation, the IC will revert to the preset switching frequency
that is set by the RFSET resistor. In this configuration the preset
frequency does not have any restrictions other than the normal
operating range of 300 to 800 kHz. During the changeover period
the IC stops switching for an approximately 5 μ s period to allow
the synchronization detection circuitry to switch over to the exter-
nal preset switching frequency.
C1
C2
C3
C4
V GATE
V COMP
I OUT
V FSET/SYNC
Although examples shown in figures 13 and 14 are extreme
cases of clock-to-resistor frequency changes, it is recommended
that actual applications not have such large switching frequency
changes. In most applications the RFSET resistor and clock fre-
quency should be very close to each other in terms of frequency.
Setting the frequencies close together will prevent the system
from experiencing large changes on frequency-dependent signals
and components, such as the inductor ripple current and the com-
pensation resistor and capacitor.
t
Figure 13. Synchronization feature with 200 kHz difference between R FSET
and external clock signal. The synchronization frequency is 600 kHz,
and the resistor preset frequency is 800 kHz. Note that there is very little
disturbance in the LED current at the time of changeover; shows
V GATE (ch1, 5 V/div.), V COMP (ch2, 1 V/div.), I OUT (ch3, 1 A/div.), and
V FSET/SYNC (ch4, 5 V/div.), t = 5 μ s/div.
LED current setting and LED dimming
The maximum LED current can be up to 150 mA per channel.
The LED current is set through the RISET resistor connected
between the ISET pin and ground. The I LED current is set accord-
ing to the following formula:
R ISET = (1.000 / I LED ) × 1160
(2)
where R ISET is in Ω , and I LED is in A. This sets the maximum cur-
rent through the LEDs, referred to as the 100% current . Standard
R ISET values are as follows:
C1
C2
C3
C4
f SW = 800 Hz from
RFSET value
V GATE
V COMP
I OUT
V FSET/SYNC
Changeover
period
f SW = 300 Hz
from SYNC pulse
Standard Resistor Value
Closest to R ISET
(k Ω )
7.87
9.53
11.5
14.3
19.1
LED current per LED, I LED
(mA)
150
120
100
80
60
t
Figure 14. Synchronization feature with 500 kHz difference between R FSET
and external clock signal, illustrating the flexibility of the RFSET/SYNC pin;
synchronization frequency is 300 kHz, and the resistor preset frequency
is 800 kHz; shows V GATE (ch1, 5 V/div.), V COMP (ch2, 1 V/div.),
I OUT (ch3, 1 A/div.), and V FSET/SYNC (ch4, 5 V/div.), t = 10 μ s/div.
11
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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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