Datasheet > AL8821

AL8821

更新时间： 2022-02-26 12:45:31

品牌	Logo	应用领域
美台 - DIODES		驱动
页数	文件大小	规格书
14页	270K
描述
BOOST LED DRIVER

阅读下载

获取价格

数据手册

如果您发现信息不准确，欢迎纠错

AL8821 数据手册

AL8821

Application Information

AL8821 Operation

The AL8821 is a boost converter that delivers an accurate constant current for driving LEDS. With hysteretic control scheme, the LED driver is

compatible with most of commonly used electronic transformers. The driver can be compatible with leading-edge dimmer and trailing-edge dimmer.

Vac

C_O

R_SET

R_HYS

VIN

VCC

R_FB

COMP

(Exposed Pad)

Figure 1. Typical Application Circuit

LED Current Control

The LED current is controlled by the resistor R_FBin Figure 1.

Connected between FB pin and Ground, the nominal average output current in the LED(s) is defined as:

0.444V

Ｉ



LED

R_FB

R_SETand R_HYSSetting

The Boost converter of the AL8821 operates at continuous conduction mode and is based on hysteresis schematic which has lower threshold and

upper threshold. Refer to Figure 2 depicting the inductor current waveform.

I_L

Peak or Upper Threshold

I_L(peak)

I_L(ave)

I_L(val)

Valley or Lower Threshold

t_ON

t_OFF

Time

Figure 2. Inductor Current

When switch SW is turned on, the inductor current flows through R_SETand ramps up linearly. The rising current produces a voltage ramp across

R_SET. When the voltage across R_SETreaches the upper threshold, switch SW is turned off. The inductor current continues to flow through R_SETbut

decays. The decaying current produces a falling voltage at R_SET. When the voltage across R_SETfalls to the lower threshold, switch SW is turned

on again.

The lower threshold voltage V_LTdepends on the voltage V_COMPat COMP pin that varies with the input voltage and output load. The equation is

shown as below.

7 of 14

www.diodes.com

February 2017

AL8821

Document number: DS37671 Rev. 2 - 2

1...4 5 678 9 10...14

下载PDF

与AL8821相关器件

型号	品牌	描述	获取价格	数据表
AL8821_17	DIODES	BOOST LED DRIVER	获取价格
AL8821SP-13	DIODES	40V, 2A BOOST LED DRIVER	获取价格
AL8822	DIODES	50V, 2A BOOST LED DRIVER	获取价格
AL8823S-13	DIODES	LED Driver,	获取价格
AL8843	DIODES	40V 3A STEP-DOWN LED DRIVER	获取价格
AL8843Q	DIODES	AUTOMOTIVE COMPLIANT 40V 3A STEP-DOWN LED DRIVER	获取价格