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LP8556: Can current sink inputs on this part be used in parallel for higher drive current?

Staci Elaan
Prodigy 15 points
Part Number: LP8556

I've got an application that uses a 22.8Vf string of white LEDs at 70mA nominal each.  I'm wondering if it's possible to parallel two channels at a time to make the LP8556 a 3-channel product but capable of my needed 210mA total current.   Does anybody know if this is possible. 

My questions for the TI team or anyone that's tried this are related to the proteciton systems on this IC.  If it is designed to detect string to string shorts I might not be able to do this.  If they're traditional mirrored current sinks then I suspect I'm in luck.   I've ordered an EVM to test this out.  With any luck the channel sinks just add :)

  • 0
    TI__Expert 4565 points

    Hi,

    LP8556 supports max 50mA per string, so it can support max 300mA total.

    It also supports various configurations of LED string. EPROM address 0xA5[6:4] = PS_MODE = 011b will set 3 strings(2 channels combined) operation.

    In this case, 2 channels works like a single channel, so LED open/short fault detection will still work.

    Other than this, you may need to consider max SW current limit. Max SW current limit of LP8556 is 2.6A, and this may limit output current if input voltage is too low.

    Hope this helps,