ADD5205 specification Fig9

Hi

We would like to know the horizontal axis of Figure-9.

20mSec/div?

Fig-10 to 13 were also missing those data.

Regards

moto

  • 0
    •  Analog Employees 
    on Jan 29, 2016 10:32 PM

    Hi Moto,

    Sorry about that.  I'll try to find the original oscope picts.  If not, I can retake that image.  Is it the time from EN to LED current that you are wondering about?  The ADD5205 does have a longer EN delay time than our other LED drivers.  This is because the PWM to DC current filter needs to gather enough PWM cycles to produce a constant filter output. 

    Best Regards,

    - Jon Kraft

  • 0
    •  Analog Employees 
    on Jan 30, 2016 5:13 AM

    Hi Moto,

    I retook the image, please see attached.  The div for Fig 9 should be 20ms.

    Best Regards,

    - Jon

  • 0
    •  Analog Employees 
    on Jan 30, 2016 5:45 AM

    Here's the attachment:

  • Hi Jon

    Thank you very much for your support.

    I got Fig9  horizontal axis was 20mSec/div

    and, Fig10 - 13 must be 1uSec/div, right?

    May I ask some questions?

    >This is because the PWM to DC current filter needs to gather enough PWM cycles to produce a constant filter output.

    Could you show us how to minimize start up time?

    Does "PWM to DC current filter" mean C_FILTER?


    When EN goes low for a moment, it needs 100msec to work again?


    Regards

    Moto

  • 0
    •  Analog Employees 
    on Feb 9, 2016 4:23 AM

    Hi Moto,

    The startup time from when EN first goes high to when the LEDs turn on is a fixed internal delay.  It is not effected by the C_FILTER value. 

    If EN goes low for a long time (more than about 100ms), then the LEDs turn off.  And if the LEDs turn off, then you will have the 60ms delay if EN goes high again.  However, if EN goes low for just a short period of time (<30 ms), then the C_FILTER averages the EN pulses and dims the LEDS to a constant DC current. 

    Please let me know if you have any other questions.

    Best Regards,

    - Jon