MIC4801 Datasheet, PDF (6/12 Pages) Micrel Semiconductor – High Efficiency 600mA Single Channel Linear WLED Driver with Ultra Fast PWM™ Control

Micrel Inc.
Functional Diagram
MIC4801
Figure 1. MIC4801 Functional Block Diagram
Functional Description
The MIC4801 is a single channel linear LED driver with a
maximum 600mA current capability. The LED driver is
designed to maintain proper current regulation with LED
current accuracy of ±10%. The dropout is 130mV at
400mA. The low dropout of the linear drivers allows the
LEDs to be driven directly from the battery voltage and
eliminates the need for boost or large and inefficient
charge pumps. The maximum LED current for each
channel is set via an external resistor. Dimming is
controlled by applying a PWM signal to the EN pin. The
MIC4801 accommodates a wide PWM frequency range
as outlined in the application information section.
Block Diagram
As shown in Figure 1, the MIC4801 consists of current
mirrors set to copy a master current determined by R_SET.
The linear LED drivers have a designated control block
for enabling and dimming of the LEDs. The MIC4801
dimming is controlled by the Ultra Fast PWM™ control
block that receives PWM signals for dimming.
January 2011
6
M9999-011811-A