MIC4802 Datasheet, PDF (6/12 Pages) Micrel Semiconductor – High Efficiency 800mA Single Channel Linear WLED Driver with Ultra Fast PWM™ Control

Micrel Inc.
Functional Diagram
MIC4802
Figure 1. MIC4802 Functional Block Diagram
Functional Description
The MIC4802 is a single channel linear LED driver with a
maximum 800mA current capability. The LED driver is
designed to maintain proper current regulation with LED
current accuracy of ±10%. The dropout is 280mV at
800mA. 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
MIC4802 accommodates a wide PWM frequency range
as outlined in the application information section.
Block Diagram
As shown in Figure 1, the MIC4802 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 MIC4802
dimming is controlled by the Ultra Fast PWM^TM control
block that receives PWM signals for dimming.
January 2011
6
M9999-013111-B