AL8820

Document number: DS37369 Rev. 1 - 2

7 of 15

www.diodes.com

December 2014

© Diodes Incorporated

AL8820

Application Information

AL8820 Operation

The device integrates two DC/DC regulators. This two stage design offers superior performance for MR16/AR111 applications. The first stage is a

boost PFC stage which improves PF, reduces EMI and conditions the input to be compatible with many of the most commonly used Electronic

Transformers (ET). This input stage also provides power for the second stage buck converter which provides regulated constant output current for

the LEDs.

D2

D1

D3

D4

D5

D6

R1

R2

C1

C2

C3

SW1

CS1

FB

COMP

SW2

VCC

VIN

CS2

(Exposed Pad)

L2

L3

C4

C5

VLED

Vac

L1

Figure 1. Typical Application Circuit

than the output voltage of buck section. For the Boost application, the output voltage can be defined as:

2

2

1

22

.

1

R

R

R

V

V

IN







The Boost converter of the AL8820 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.

Time

Peak or Upper Threshold

Valley or Lower Threshold

Figure 2. Inductor Current

SW1 is turned on again.

shown as below.