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LM5170-Q1: Things to be taken care while using two LM5170 to drive four phases

Albin Vinu30
Prodigy 210 points
Part Number: LM5170-Q1
Other Parts Discussed in Thread: LM5170

Hi,

I have taken care below points to drive four phases using two LM5170. Is this right?

a) Connected OPT pin of both IC to high

b) Connected SYNCIN of driver 1 to controller

c) Connected SYNCOUT of driver 1 to SYNCIN of driver 2

d) Connected SYNCOUT of driver 2 to ground using 10K resistor since fault function is taken care by driver 1

e) Connected BRKG of both the drivers to gate of breaker MOSFET.

f) Connected BRKS of both the drivers to source of breaker MOSFET

g) Tied EN1, EN2, IOUT1, IOUT2, ISETA pins of both drivers to controller

h) Tied SS pin of both drivers together and added capacitor to individual pin

Please let me know whether this configuration will work out well for my application (Two driver IC's for four phase DC DC converter - 48V to 12V).

Thanks,
Albin

  • 0
    TI__Guru* 78240 points
    Hi Albin,

    Thank you for considering the LM5170 in your project. Your setup is basically correct except d). When using breaker function, both LM5170 do the failure detection independently. So, do not populate the 10k resistor.

    Best Regards,
    Youhao Xi, System and Applications Engineering, APP-BMC-BCS, TI
  • 0 in reply to Youhao Xi
    Prodigy 210 points

    Hi Youhao,

    Thanks for addressing!

    In that case, do i need to connect same resistors for OVPA and OVPB in both drivers. Because, when i enable fault detection by not populating 10k grounded w.r.t SYNCOUT of second driver over voltage detection function also will come into picture right?

    Thanks,

    Albin 

  • 0 in reply to Albin Vinu30
    TI__Guru* 78240 points
    You only need one LM5170 to fulfill the OVPA and OVPB functions, and tie the SS pins of both IC together. The non-used OVPA and OVPB pins should be grounded or pull down to GND by small resistors.

    If this answers your question, please reply by click on the "This solved my issue" button. You may ask further questions in a new post.

    Thanks,
    Youhao
  • 0 in reply to Youhao Xi
    Prodigy 210 points

    Hi Youhao,

    I have one another question regarding the topic of using two LM5170 to driver four phases. 

    If nFAULT pin of both drivers are tied together and UVLO pin of second driver is kept low (<1.25V), will the nFAULT signal be pulled down and deactivate first driver too?

    Thanks,
    Albin

  • 0 in reply to Albin Vinu30
    TI__Guru* 78240 points
    Yes it will disable the 1st IC, too.