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MIC3205

High-Brightness LED Driver Controller with Fixed-Frequency Hysteretic Control

Micrel 

MIC3205

High-Brightness LED Driver Controller

with Fixed-Frequency Hysteretic Control

General Description

The MIC3205 is a hysteretic, step-down, high-brightness

LED (HB LED) driver with a patent pending frequency

regulation scheme that maintains a constant operating

frequency over input voltage range. It provides an ideal

solution for interior/exterior lighting, architectural and

ambient lighting, LED bulbs, and other general illumination

applications.

The MIC3205 is well suited for lighting applications

requiring a wide input voltage range. The hysteretic control

provides good supply rejection and fast response during

load transients and PWM dimming. The high-side current

sensing and on-chip current-sense amplifier deliver LED

current with 5% accuracy. An external high-side current-

sense resistor is used to set the output current.

The MIC3205 offers a dedicated PWM input (DIM) which

enables a wide range of pulsed dimming. A high-frequency

switching operation up to 1.5MHz allows the use of smaller

external components minimizing space and cost.

The MIC3205 operates over a junction temperature from

–40°C to +125°C and is available in a 10-pin 3mm x 3mm

MLF® package.

Data sheets and support documentation are available on

Micrel’s web site at: www.micrel.com.

Features

 4.5V to 40V input voltage range

 Fixed operating frequency over input voltage range

 High efficiency (90%)

 5% LED current accuracy

 High-side current sense

 Dedicated dimming control input

 Hysteretic control (no compensation!)

 Up to 1.5MHz switching frequency

 Adjustable constant LED current

 Over-temperature protection

 –40C to 125C junction temperature range

Applications

 Architectural, industrial, and ambient lighting

 LED bulbs

 Indicators and emergency lighting

 Street lighting

 Channel letters

 12V lighting systems (MR-16 bulbs, under-cabinet

lighting, garden/pathway lighting)

_________________________________________________________________________________________________________________________

Typical Application

Normalized Switching Frequency

vs. Input Voltage

2.0

ILED = 1A

RCS = 0.2Ω

1.5

1 LED

L = 22µH

1.0

4 LED

0.5 L = 47µH

6 LED

L = 68µH

10 LED

L = 33µH

0.0

0

9

18

27

36

45

INPUT VOLTAGE (V)

MIC3205 Buck LED Driver

MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

October 2012

M9999-102312-A

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