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Original question:

LP8553 3 channel operation

LP8553: 1, 2 and 4 channels application with LP8553.

Gilbert Liu
Prodigy 250 points
Part Number: LP8553
Other Parts Discussed in Thread: LP8552, LP8556

Hi TI,

I have multiple applications are possible to use this LP8553, which have 1, 2 and 4 channels.

So do you have a recommendation how to assign the channels?

Refer to your first comment, on the 2 channels usage, should i ties Ch 1 and 4, then Ch 2 and 3 for 2 channels usage?

Any recommendation for the 1 channel application?

Thanks in advance!

Gilbert

  • 0
    Prodigy 250 points

    Hi,

    In fact, I think there maybe a 3 channels application, so can i use it for 3 channels application if we want to use this LP8553?

    Thanks,

    Gilbert

  • 0 in reply to Gilbert Liu
    TI__Genius 15776 points

    Hi Hardy could you help in this case

  • 0 in reply to Gilbert Liu
    TI__Genius 12915 points

    Hi Gilbert,

    I think it is depended on how much current your system requires. If for your 1, 2 & 3 channel application and less than 50mA is need, you could simple float the unused channel. The corresponding LED string would be taken out of boost adaptive control loop when this channel opened. Other function would be normal but fault pin cannot be used.

    If you want to tie 2 channels or 4 channels together, phase shift function is recommended disable, since all 4 channels have different phase. There is no specific tie order.

  • 0 in reply to Hardy Wu
    Prodigy 250 points

    Hi Hardy,

    Thanks for your recommendation.

    For my curiosity, I read the other post "LP8553 3 Channel Operation" in this forum, this is why I noticed the channel tie option.

    There was a recommended tie order in the LP8552, what about this LP8553?

    All my applications are less than 50mA and do you have any recommendation if I still want to use the fault signal?

    Thanks,

    Gilbert

  • +1 in reply to Gilbert Liu
    TI__Genius 12915 points

    Hi Gilbert,

    I think in former thread that it is recommended to tie the reverse PWM phase channels together. For duty cycle >50% there still would have 2 channels opened together. Considering this for LP8553 you could tie channel 1 with 3 and channel 2 with 4. For this device there is no simple onoff function for single channel. You could take a look of LP8556 which could support your application by turn off unused channels.

  • 0 in reply to Hardy Wu
    Prodigy 250 points

    Hi Hardy,

    Thanks for your advice.

    Gilbert