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LM5171: Input connection in multiphase operation (boost)

Darren DeBattista1
Intellectual 525 points
Part Number: LM5171

Tool/software:

Hi,

I am considering the LM5171 for a boost application powered by two independent batteries, one connected to each channel of the LV side, while the HV side would be paralleled. I want to achieve current sharing and thus, the ISET needs to be connected together as shown in datasheet and other various documentation. 

1. Would there be any issues giving that the two batteries might have different voltage level supplying the two channels?

2. If only one battery is connected, will this have a negative effect on the circuit (especially since ISET would be shorted together)?

EDIT: Additionally, I also need to connect two LM5171 devices in parallel (4 batteries in total). There is the possibility that the user connects any number of batteries from 1 to 4. While I can use combinational logic to determine the OPT value to use depending on the number of batteries connected, my doubt resides in when the user will connect only two batteries, and it happens that one battery is on one LM5171 and the second battery is on the second LM5171. In such case, will the interleaving happen at the correct 180 degrees if I set OPT = 1, or will it be only at 90 degrees given the 90 degree phase of the SYNCO signal? If so, is there any solution to this?

Thanks

  • +1
    TI__Mastermind 22650 points

    Hi Darren,

    1. I don't see any issue with different LV voltage.

    2.The channels are independent. I don't see any negative effect. Maybe you would prefer to shut down the idle channel to save some power.

    3. Only 90° or 120° phase shift is supported between two LM5171 with SYNCO. It is not perfect 180° interleaving. But I don't think this is a big issue. If you want to have perfect 180° interleaving, you have to send clock signals to both LM5171 (with MCU). You can adjust the phase shift between the two clock signals with MCU.

    Best Regards,

    Feng