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参数资料
| 型号： | A8504EECTR-T |
| 厂商： | Allegro Microsystems Inc |
| 文件页数： | 13/19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
7. Select output capacitor COUT (connect between the A8504
and the LEDs), given:
The rms current through capacitor should be selected such
that internally-generated temperature rise is limited to 10°C.
C OUT = I OUT × t on / ? V OUT ,
(9)
The rms current through CBAT is given by:
where I OUT is the total output current, and ? V OUT is the
output voltage ripple, 0.5% of V OUT (0.05 × 27.7 = 0.14 V).
Then:
I BATrms = ( I OUT × r) / [(1 – D) × 3.46 ],
= [(40 mA × 6 )× 0.6] /
(12)
C OUT = (40 mA × 6) × 370 ns / 0.14 = 0.63 μ F .
Select a ceramic capacitor with a 35 or 50 V rating, X5R or
X7R grade. Usually capacitance at 35 V drops significantly
compared to the 0 V specification. Typically, this requires the
selection of a 2.2 μ F capacitor to compensate for DC voltage
bias derating.
The rms current through capacitor should be selected such
that internally-generated temperature rise is limited to 10°C
to 20°C. The rms current through COUT is given by:
[(1 – 0.74) × 3.46] = 160 mA .
9. Select the boost diode D1 (connect between the SW pins and
the output). D1 should be a Schottky diode with low forward
drop and junction capacitance.
The diode reverse voltage rating should be greater than V OUT .
A 50 V diode rating is recommended.
The diode DC current rating should be greater than I OUT
and the peak repetitive current rating should be greater than
I COUTrms = I OUT × [(D+r 2 / 12) / (1 – D)] 1/2 ,
where r = ? I L / I BAT = 0.554 mA /0.923 mA = 0.6.
COUT should have an rms current rating greater than:
(10)
I BAT + ? I L / 2.
10. Select the compensation capacitor CC (connect between
the COMP pin and ground. Typically, use a 0.1 to 0.47 μ F
(40 mA × 6 )× {[0.74 + (0.36 /
12)]/(1–0.74)} 1/2
= 0.48 A.
capacitor for stability.
8. Select input capacitor CBAT (connect to battery input),
given:
High Output Current Operation
LED strings can be paralleled for higher current. The A8504
C BAT = ? I L / (V BAT (min) × f SW × ? V INripple ,
(11)
can sink up to 40 mA through each sink. These outputs can be
where ? V INripple is the input ripple voltage, which can be as-
sumed to be 1% of V BAT . Then:
C IN = 0.554 mA/(8 × 2 MHz × 0.08) = 0.4 μ F .
Select a 1 μ F or higher, 25 or 35 V, ceramic capacitor, X5R or
X7R grade.
Quantity
connected together with various possibilities for higher current
as shown in figure 7. As an example, for an application with up
to 50 mA using 3 parallel strings: LED1 connected with LED2,
LED3 with LED4, and LED5 with LED6; LED7 and LED8 open;
SEL1 and SEL3 set logic high, and SEL2 set low.
I LED (max)
of Strings
SEL1
SEL2
SEL3
LED1
LED2
LED3
LED4
LED5
LED6
LED7
LED8
25
8
H
H
H
25
7
L
H
H
NC
25
6
H
L
H
NC
NC
25
5
L
L
H
NC
NC
NC
25
4
H
H
L
NC
NC
NC
NC
25
3
L
H
L
NC
NC
NC
NC
NC
25
2
H
L
L
NC
NC
NC
NC
NC
NC
25
1
L
L
L
NC
NC
NC
NC
NC
NC
NC
50
4
H
H
H
Connect
Connect
Connect
Connect
50
3
H
L
H
Connect
Connect
Connect
NC
NC
50
2
H
H
L
Connect
Connect
NC
NC
NC
NC
50
1
H
L
L
Connect
NC
NC
NC
NC
NC
NC
100
2
H
H
H
Connect
Connect
100
1
H
H
L
Connect
NC
NC
NC
NC
200
1
H
H
H
Connect
Figure 7. LED strings can be combined to allow various maximum current levels to be applied.
The “Connect” notes indicate LED strings connected together.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1 . 508.853.5000; www.allegromicro.com
12
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| 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 |
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