MIC3202 datasheet(9/19 Pages) MICREL

9 / 19 page

Micrel, Inc.

MIC3202

September 2010

M9999-091710-A

Functional Diagram

Figure 1. MIC3202/MIC3202-1 Functional Block Diagram

Functional Description

The MIC3202 is a hysteretic step-down driver which

regulates the LED current over wide input voltage range

and capable of driving up to eight 1A LEDs in series.

The device operates from a 6V to 37V input. When the

input voltage reaches 6V, the internal 5V VCC is

regulated and the LX pin is pulled low if the EN pin and

DIM pin are high. The inductor current builds up linearly.

When the CS pin voltage hits VCS(MAX) with respect to VIN,

the MOSFET turns off and the Schottky diode takes over

and returns the current to VIN. Then the current through

inductor and LEDs starts decreasing. When CS pin hits

VCS(MIN), the MOSFET turns on and the cycle repeats.

The frequency of operation depends upon the input voltage,

total LED voltage drop, LED current and temperature. The

calculation for frequency of operation is given in the

Application Information

section.

The MIC3202 has an EN pin which gives the flexibility to

enable and disable the output with logic high and low

signals.

The MIC3202 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%.

MIC3202 Datasheet(PDF) 9 Page - Micrel Semiconductor