AL8806MP8-13 Diodes Zetex, AL8806MP8-13 Datasheet - Page 12

• Manufacturer Part Number: AL8806MP8-13
• Manufacturer: Diodes Zetex

Specifications of AL8806MP8-13

• Lead Free Status / Rohs Status: Supplier Unconfirmed

AL8806
HIGH EFFICIENCY 30V 1.5A BUCK LED DRIVER
(PRELIMINARY)
Applications Information
(cont.)
PWM Dimming (cont.)
The PWM pin is designed to be driven by both 3.3V and 5V logic levels directly from a logic output with either an open drain
output or push-pull output stage.
Soft Start
The AL8806 does not have in-built soft-start action – this provides very fast turn off of the output the stage improving PWM
dimming accuracy; nonetheless, adding an external capacitor from the CTRL pin to ground will provide a soft-start delay. This
is achieved by increasing the time taken for the CTRL voltage to rise to the turn-on threshold and by slowing down the rate of
rise of the control voltage at the input of the comparator. Adding a capacitor increases the time taken for the output to reach
90% of its final value, this delay is 0.1ms/nF, but will impact on the PWM dimming accuracy depending on the delay
introduced.
Figure 4. Soft start with 22nF capacitor on CTRL pin (V
= 30V, I
= 667mA, 1 LED)
IN
LED
AL8806 (Preliminary)
12 of 16
February 2011
© Diodes Incorporated
www.diodes.com
Document number: DS35144 Rev. 1 - 1