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LP5024: 12 bit PWM

Yoav Bar-yoseph
Prodigy 130 points
Part Number: LP5024
Other Parts Discussed in Thread: TLC59116, , TLC5973, LP5009

Hi,

can you supply a bit elaborated description about how to achieve 12 bit PWM resolution, how exactly registers should be configured?

I understood that 9 bit resolution by summing color and brightness register - so having 0xFF+0xFF=0x1FE=510 steps.

We did not quite understood the dithering mechanism and how many steps are achieved by using it.

Thanks,

Yoav

  • 0
    TI__Genius 12915 points

    Hi Yoav,

    Here is a integrated algorithm to combine 8-bit brightness setting and 8-bit PWM setting into a 12-bit PWM output. Every step of 12-bit can get by the combination.

    The integrated 9-bit PWM generator plus 3-bit dithering is a way to achieve 12-bit PWM output for each channel. You can consider it as a 'fake' 12-bit achieved by making every eighth pulse 1 LSB longer, to increase the average value by 1 / 8th. The display performance is the same as 12-bit.

  • 0 in reply to Hardy Wu
    Prodigy 130 points

    Thanks,

    I read that info in the data sheet, however did not yet quite understand it.

    When dithering is disabled, then there is a sum of two 8 bit registers (color+brightness) which provides us up to 510 steps.

    When setting dithering to enable, how exactly the calculation is done, as I did not really understood how to set the bits in those two registers (I actually require 3,000 steps).

    Another questions, in another thread I was looking into a device similar to tlc59116 with 12 but resolution PWM.

    Will the LP5024 fit for it (as you have replied to me with other devices and did not specify the LP5024.

    Thanks,

    Yoav

  • 0 in reply to Yoav Bar-yoseph
    TI__Genius 12915 points

    Hi Yoav,

    Output PWM would be calculated by internal algorithm with brightness value multiple by PWM value. Sorry that I cannot share you with the details. All 4096 step could be get by the combination of brightness setting and PWM setting. But brightness would set 3 channels as a group together. 12-bit may cannot achieve all channels individually. 

    For another thread, I thought you already knew LP5024 but need other 12-bit device. For PWM requirement of 12-bit, LP5024 is fit. You could check if other spec like output current, channel number or others is also fit for you. 

  • 0 in reply to Hardy Wu
    Prodigy 130 points

    Thanks for your reply.

    Actually we have only 1 single LED that have to be controlled.

    You mentioned that all 4096 steps can be aceived - can you elaborate the registers assignement for that?

    Maybe supply few examples and from there I would be able to go on:

    * 1/4096 PWM

    * 2/4096 PWM

    * 100/4096 PWM

    * 1000/4096 PWM

    * 4096/4096 PWM

    Thanks,

    Yoav

  • 0 in reply to Yoav Bar-yoseph
    TI__Genius 12915 points

    Hi Yoav,

    How much the maximum output current you need? You could have a look of TLC5973 to see if it is suitable for you, which is 12-bit PWM with single wire interface. If I2C is must, LP5009, which have 9 channel and other spec is the same as LP5024, may suitable for one LED.

    1/4096 PWM = 01h brightness with 1xh color 

    2/4096 PWM = 01h brightness with 2xh color 

    100/4096 PWM = 07h brightness with E4h or E5h color 

    1000/4096 PWM = 46h brightness with E3h color 

    4096/4096 PWM = FFh brightness with FFh color 

  • 0 in reply to Hardy Wu
    Prodigy 130 points

    Thanks,

    however I am still missing something in how to set registers value to get all steps 0..4095

    Yoav

  • 0 in reply to Hardy Wu
    Prodigy 130 points

    Is there an option to have the following table filled - with all PWM options (0-4096) as we could not understand how to assign the registers...

    PWM Brightness Register Color Register
    0/4096
    1/4096
    ...
    ...
    4096/4096

    Thanks,

    Yoav

  • 0 in reply to Yoav Bar-yoseph
    TI__Genius 12915 points

    Hi Yoav,

    Here is an example for every bits. Sorry for the wrong statement before, there are some bits cannot achieve for high value.

    Bri x col table.xlsx

  • 0 in reply to Hardy Wu
    Prodigy 130 points

    Thanks a lot.

    That was a great help!