MIC3205
High-Brightness LED Driver Controller
with Fixed-Frequency Hysteretic Control
General Description
Features
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.
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
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.
–40C to 125C junction temperature range
Applications
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.
Architectural, industrial, and ambient lighting
LED bulbs
Indicators and emergency lighting
Street lighting
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.
Channel letters
12V lighting systems (MR-16 bulbs, under-cabinet
Data sheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
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
10 LED
L = 33µH
6 LED
L = 68µH
L = 47µH
0.5
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
M9999-102312-A
October 2012