Constant-Current 3-Ampere PWM Dimmable

Buck Regulator LED Driver

A6211

13

Allegro MicroSystems, Inc.

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Application Circuit

The application circuit in figure 14 shows a design for driving

quency is 500 kHz, as set by R1. A 0.68 μF ceramic capacitor is

added across the LED string to reduce the ripple current through

the LEDs (as shown in figure 13B).

LED+

LED–

VIN

TON

EN

CS

SW

BOOT

GND

VCC

A6211

1

2

3

4

8

7

6

5

C1

47 μF

50 V

C2

4.7uF

50V

EN

C4

0.1 μF

R1

140 kΩ

L1

10 μH / 2 A

C5

0.1 μF

0.15 Ω

GND

D1

60 V / 2 A

C3

0.68 μF

50 V

LED

string

Figure 14. Application circuit diagram

Suggested Components

Symbol

Part Number

Manufacturer

C1

EMZA500ADA470MF80G

United Chemi-Con

C2

UMK316BJ475KL-T

Taiyo Yuden

L1

NR8040T100M

Taiyo Yuden

D1

B250A-13-F

Diodes, Inc.

RL1632R-R150-F

Susumu