- 您现在的位置：买卖IC网 > Datasheet目录306 > A8504EECTR-T (Allegro Microsystems Inc)IC LED DRVR WHT/RGB BCKLGT 26QFN Datasheet资料下载
参数资料
| 型号： | A8504EECTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 12/19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 |
| 输出电压： | 47V |
| 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： | 1141 (CN2011-ZH PDF) |
| 其它名称： | 620-1215-6 |
A8504
WLED/RGB Backlight Driver for Medium Size LCDs
Application Information
Design Example
This section provides a method for selecting component values
when designing an application using the A8504.
Assumptions For the purposes of this example, the following are
given as the application requirements:
? V BAT : 8 to 21 V
? V IN : 5 V
? Quantity of LED channels: 6
? Quantity of LEDs per channel: 8
? LED current per channel, I LED : 40 mA
? V f at 40 mA: 3 to 3.4 V
? f SW : 2 MHz
? T A (max): 65°C
5. Select resistor ROVP (connect to the OVP pin to set the OVP
level, V OUT (max)). Given V f (max) = 3.4 V, then:
V OUT (max) = 3.4 × 8 + 0.5 = 27.7 V . (3)
With a 15% margin, to set the output OVP level, given an
I OVPH of 49 μ A typical, and V OVP = 30 V:
R OVP = (32 – 30) / 49 = 40.8 k Ω . (4)
Select a common value: 41.2 k Ω .
6. Select inductor L1. This should assume a maximum duty
cycle, D(max), at V BAT (min) and 90% efficiency.
D = 1– ( V BAT × η ) / V OUT (5)
D(max) = 1– (8 × 0.9) / 27.7 = 74% .
Dimming Use a 100 Hz PWM signal on the PWM pin. The
A8504 can work with wide range of PWM frequencies, taking
about 6 μ s typical (10 μ s maximum) to turn on. This delay may
have a noticeable effect at high PWM frequencies combined with
low duty cycles. For example, at 100 Hz and 10% duty cycle, the
PWM on-period is 1 ms. In that period, a delay of 6 μ s causes
only a 0.6% error. If the PWM frequency is 1 kHz, this error
is 6%. However, error due to turn-on delay can be nullified by
increasing the applied PWM duty cycle.
Procedure The procedure consists of selecting the appropriate
configuration and then the individual component values, in an
ordered sequence.
1. Identify the SEL x pins to use. For 6 channels:
? connect pins SEL1 and SEL3 to V IN
? connect pin SEL2 to AGND
2. Connect LEDs to pins LED1 through LED6 (leave pins
Then calculate maximum switch on-time:
t on (max) = D (max) / f SW
= 0.74 / 2 MHz = 370 ns .
Maximum input current can be calculated as:
I BAT = ( V OUT × I OUT ) / ( V BAT (min) × η )
I BAT (max) = [27.7 (40 × 6)] / (8 × 0.9) = 923 mA .
Set inductor ripple at 60% of I BAT (max):
? I L = 0.6 × 923 = 554 mA
Given, during switch on-time:
V BAT = L × ? I L × f SW / D
8 = L × 0.554 × 2 / 0.74, and
(6)
(7)
(8)
LED7 and LED8 open).
3. Select resistor RISET (connected between pin ISET and
AGND). Given I LED = 40 mA and V ISET = 1.23 V typical,
then:
R ISET = 1.23 / (40/460) = 14.2 k Ω . (1)
Select a common value: 14.3 k Ω , 1%.
4. Select resistor RFSET (connected between pin FSET and
AGND). Given:
L = 5.3 μ H .
Select a common value, 6.8 μ H.
It is recommended to select an inductor that can handle a DC
current level that is greater than 923 mA, at the peak current
level (saturation) of 923 mA + 554 / 2 = 1200 mA. This is
to ensure that the inductor does not saturate at any steady
state or transient condition, within specified temperature and
tolerance ranges. Inductor saturation level decreases with
R FSET = 26.03 /f SW ,
for a 2 MHz switching frequency, select:
R FSET = 26.03 / 2 = 13 k Ω .
(2)
increasing temperature. It is advisable to use a inductor with
a saturation level of 1.6 A, because the switch current limit
is 1.8 A typical. The inductor should have a minimum DC
resistance and core loss for better efficiency.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1 . 508.853.5000; www.allegromicro.com
11
相关PDF资料 |
PDF描述 |
|---|---|
| A8507ELBTR-T | IC DRIVER WLED/RGB 24-SOIC |
| A8508GLPTR-T | IC LED DVR WHITE 8X120MA 24TSSOP |
| A8509GLPTR-T | IC LED DVR WHITE 4X120MA 24TSSOP |
| A8510GECTR-T | IC LED DRVR BCKLGHT/WHT 26QFN-EC |
| A8511KLPTR-T | IC LED DVR 150MA AUTO 28-TSSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| A8507 | 制造商:ALLEGRO 制造商全称:Allegro MicroSystems 功能描述:LED Backlight Driver for LCD Monitors and Televisions |
| A8507ELBTR-T | 功能描述:IC DRIVER WLED/RGB 24-SOIC 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 |
| A8507ELPTR-T | 功能描述:IC LED DVR WHT/RGB BKLGT 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 |
| A8508 | 制造商:ROCKWE 功能描述: |
| A8508GLPTR-T | 功能描述:IC LED DVR WHITE 8X120MA 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 |
发布紧急采购，3分钟左右您将得到回复。