3 A, 2 MHz Buck-Regulating LED Driver

A6210

9

Allegro MicroSystems, Inc.

115 Northeast Cutoff

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

1.508.853.5000; www.allegromicro.com

TON

DIS

PWM or Switch

GND

NC

L

D1

1

47 μH

LX

VIN

ISEN

SGND

A 6210

22 nF

R1

910 kΩ

C1

1.0 μF

150 mΩ

R2

C2

BOOT

V

IN

42 V

R3

910 kΩ

LED

Assembly

Average LED current = 1.34 A

Peak to peak current = 200 mA

LED Assembly voltage = 24 V

Switching frequency = 1.0 MHz

Efficiency = 90.5%

Other Application Circuits

Application Circuit 1

Suggested Parts

Name

Description

Manufacturer - Part Number

C1

1 μF, 25V, X5R or X7R ceramic, 1210

Taiyo Yuden, TDK

C2

22 nF, 50V, X5R or X7R ceramic, 0805

D1

3 A, 60 V, Schottky diode

L1

47 μH, 1.4 A inductor

Taiyo Yuden - NR 8040T 470M

R1, R3

910 kΩ, 1%, 0603

R2

150 mΩ, 1%, 1206

Plot 1. Average current = 1.34 A

Plot 2. Peak to peak current = 200 mA

Plot 3. PWM frequency = 10 kHz, maximum duty cycle

Plot 4. PWM frequency = 10 kHz, minimum duty cycle

Plot 5. Plot 4 with expanded time scale

Plot 6. PWM frequency = 10 kHz, turn off

Channel 1 – Current through inductor and LED Assembly, Channel 2 – Main switching voltage (LX node)