MIC2287 (MLF™) Evaluation
Board
1.2MHz PWM White LED
Driver
General Description
The MIC2287 is a small 1.2MHz constant frequency
PWM white LED driver. The MIC2287 is available in
either a Thin SOT-23 or a 2mm x 2mm MLF™
package. High power densities in a very small size
are achieved using its internal 34V/500mA switch.
Requirements
LED Current Setting
The LED current (I
LED
) is equal to the feedback
voltage (95mV typical) divided by the R1 resistance
value. To increase the LED current, the R1 resistor
value must be reduced. Conversely, to decrease the
LED current the R1 resistor value must be increased.
The LED current can be calculated as follows:
The MIC2287 evaluation board requires an input
power source that is able to deliver greater than
I
LED
=
95mV
R1
500mA at 2.5V.
Precautions
The evaluation board does not have reverse polarity
protection. Applying a negative voltage to the V
IN
terminal may damage the device.
The MIC2287 evaluation board is tailored for a Li-Ion
range input supply voltage. It should not exceed 10V
on the input.
Getting Started
1. Connect an external supply to V
IN
. Apply
desired input voltage to the V
IN
(J1) and
ground (J2 and J6) terminals of the
evaluation board, paying careful attention to
polarity and supply voltage (2.5V≤V
IN
≤10V).
An ammeter may be placed between the
input supply and the V
IN
terminal to the
evaluation board. Ensure that the supply
voltage is monitored at the V
IN
terminal. The
ammeter and/or power lead resistance can
reduce the voltage supplied to the input.
2. Enabling the MIC2287. Apply a 1.5V or
greater voltage source to the enable (J3)
terminal.
The evaluation board is preset for ~15mA of LED
current. The evaluation board can easily be modified
to yield the desired LED current by replacing the R1
resistor value.
MLF and MicroLeadFrame are a registered trademark of Amkor Technology.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax 1 (408) 474-1000 • http://www.micrel.com
May 2005
M9999-052005
(408)
955-1690
