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| 型号： | A8500EECTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 8/16页 |
| 文件大小： | 0K |
| 描述： | IC LED DRVR WHT/RGB BCKLGT 26QFN |
| 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： | RGB，白色 LED |
| 频率： | 200kHz ~ 2MHz |
| 电源电压： | 4.2 V ~ 5.5 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 ~ 85°C |
| 产品目录页面： | 1142 (CN2011-ZH PDF) |
| 其它名称： | 620-1204-6 |
A8500
Flexible WLED/RGB Backlight Driver
for Medium Size LCDs
Functional Description
The A8500 is a multioutput WLED driver for medium display
backlighting. The A8500 works with 4.2 to 5.5 V input supply,
and it has an integrated boost converter to boost a 5 V battery
voltage up to 47 V, to drive up to 12 WLEDs in 6 series (V f =
3.2 V, I f = 20 mA), or 8 WLEDs in 8 series at 20 mA per LED
string. For higher LED power or more LEDs, an inductor can be
connected to a separate power supply, V BAT , from 5 to 25 V, with
the A8500 IC powered from a 5 V source. The LED sinks can
sink up to a 25 mA current.
The boost converter is a constant frequency current-mode con-
verter. The integrated boost DMOS switch is rated for 50 V at
2 A. This switch has pulse-by-pulse current limiting, with the cur-
rent limit independent of duty cycle. The switch also has output
overvoltage protection (OVP), with the OVP level adjustable,
typically from 30 to 47 V, as described in the Device Internal
Protection section.
The A8500 has individual open LED detection. If any LED
opens, the corresponding LED pin is removed from regulation
logic. This allows the remaining LED strings to function nor-
mally, without excessive power dissipation.
The switching frequency, f SW , can be set from 600 kHz to 2 MHz
by a single resistor, RFSET, connected across the FSET and
AGND pins, and with the SKIP pin set to logic low (see figure 2).
The switching frequency is set as:
f SW = 26.03 / R FSET ,
where f SW is in MHz and R FSET is in k Ω When the SKIP pin is
connected to logic low, switching frequency is as set by RFSET.
2.5
When the SKIP pin is connected to logic high, the switching
frequency is divided by 4. The SKIP pin can be used to reduce
switching frequency in order to reduce switching losses and
improve efficiency at light loads.
The IC offers a wide-bandwidth transconductance amplifier with
external COMP pin. External compensation offers optimum per-
formance for the desired application.
The A8500 has eight well-matched current sinks to provide regu-
lated current through LEDs for uniform display brightness. The
quantity of LED x pins used is determined by the SEL x pins. Refer
to table 1 for further description.
The boost converter is controlled such that the minimum voltage
on any LED x pin is 500 mV. In a typical application, the LED x
pin connected to the LED string with the maximum voltage drop
controls the boost loop, so the remaining pins will also have the
higher voltage drop. All LED sinks are rated for 21 V, to allow
PWM dimming control.
LED Current Setting
The maximum LED current can be set at up to 25 mA per chan-
nel, by using the ISET pin. To set the reference current, I SET ,
connect a resistor, RISET, between this pin and ground, valued
according to the following formula:
I SET = 1.23 / R ISET ,
where I SET is in mA and R ISET is in k Ω .
Table 1. LEDx Channel Enable Table
2.0
1.5
1.0
0.5
SEL1
0
1
0
1
0
1
SEL2
0
0
1
1
0
0
SEL3
0
0
0
0
1
1
LED x Outputs
Only LED1 on
LED1 through LED2 on
LED1 through LED3 on
LED1 through LED4 on
LED1 through LED5 on
LED1 through LED6 on
0
0
10
20
30
40
50
60
70
0
1
1
1
1
1
LED1 through LED7 on
LED1 through LED8 on
R FSET (k Ω )
Figure 2. Switching frequency setting by value of RFSET.
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| A8501 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:2 MHz, 4 Channel100 mA WLED/RGB Driver |
| A85014-000 | 制造商:TE Connectivity 功能描述:POLYOLEFINS ETC - Bulk 制造商:TE Connectivity 功能描述:MIL-LT-1/2-6-FSP-CS7223 |
| A8501ELPTR-T | 功能描述:IC LED DRVR WT/RGB BKLGT 28TSSOP 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 |
| A8501KLPTR-T | 功能描述:IC LED DVR WHT/RGB BKLGT 28TSSOP 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 |
| A8502 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:Wide Input Voltage Range, High Efficiency |
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