mic3203 Micrel Semiconductor, mic3203 Datasheet - Page 10

• Manufacturer Part Number: mic3203
• Description: High-brightness Driver Controller With High-side Current Sense
• Manufacturer: Micrel Semiconductor

Functional Diagram
Functional Description
The MIC3203 is a hysteretic step-down driver which
regulates the LED current over wide input voltage range.
The device operates from a 4.5V to 42V input MOSFET
voltage range and provides up to 0.5A source and 1A
sink drive capability. When the input voltage reaches
4.5V, the internal 5V VCC is regulated and the DRV pin
is pulled high to turn on an external MOSFET if EN pin
and DIM pin are high. The inductor current builds up
linearly. When the CS pin voltage hits the V
respect to V
diode takes over and returns the current to V
current through inductor and LEDs starts decreasing.
When CS pin hits V
cycle repeats.
Micrel, Inc.
March 2010
IN
, the MOSFET turns off and the Schottky
CS(MIN)
, the MOSFET turns on and the
Figure 1. MIC3203/MIC3203-1 Block Diagram
IN
CS(MAX)
. Then the
with
10
The frequency of operation depends upon input voltage, total
LEDs voltage drop, LED current and temperature. The
calculation for frequency of operation is given in application
section.
The MIC3203 has an on board 5V regulator which is for
internal use only. Connect a 1µF capacitor on VCC pin to
analog ground.
The MIC3203 has an EN pin which gives the flexibility to
enable and disable the output with logic high and low
signals.
The MIC3203 also has a DIM pin which can turn on and off
the LEDs if EN is in HIGH state. This DIM pin controls the
brightness of the LED by varying the duty cycle of DIM pin
from 1% to 99%.
M9999-032910-A
MIC3203