MIC2845 Datasheet, PDF (13/21 Pages) Micrel Semiconductor – 6 Channel High Side Current Source WLED driver

Micrel Inc.
Application Information
MIC2845 PWM Dimming Interface
The MIC2845 can receive PWM signals from the END
pin for WLED dimming. The frequency of the PWM
signal should be between 200Hz – 1kHz and the duty
cycle can range from 1% to 100%. Dimming is
generated by pulsing the WLEDs on and off in
synchronization with the PWM signal. An internal
shutdown delay ensures that the internal control circuitry
remains active during PWM dimming for optimum
performance. Figure 4 through Figure 8 show the WLED
current response when a PWM signal is applied to the
END pin.
MIC2845/46
Figure 6. PWM Signal at 50% Duty Cycle
Figure 4. PWM Signal at 1% Duty Cycle
Figure 7. PWM Signal at 80% Duty Cycle
Figure 5. PWM Signal at 20% Duty Cycle
Figure 8. PWM Signal at 100% Duty Cycle
January 2008
13
M9999-010808-A