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LM5050-1: Questions about -48V usage

Kazuhiko Hirano
Genius 13278 points
Part Number: LM5050-1
Other Parts Discussed in Thread: LM5050MK-1EVAL, LM5051, TPS23521

Q1

At Figure 31 of the datasheet, since this is Vin=-48V case, VIN and Vout should be 0V and GND should be -48V as follows by right?

Q2

My customer does not understand well what the D3(SS16T3) is doing at Figure 31. Could you elaborate?

Q3-1

My customer would like to evaluate -48V case using LM5050MK-1EVAL.

In this case the flowing connections are correct?


Q3-2

Up to how much A current can this LM5050MK-1EVAL be used?

Since my customer replace the external FET by a much bigger one, you do not need to consider FET thermal performance.

 

Best regards,

 

K.Hirano



  • 0
    TI__Genius 13278 points

    Hello,

     

    My customer has been waiting for answers to this e2e thread for five days.

     

    Can anyone answer my customer's question?

     

    Best regards,

     

    K.Hirano

  • 0 in reply to Kazuhiko Hirano
    TI__Guru** 103876 points

    Hi Hirano-san

    Apologies for the delay. This thread got missed due to change in the role and responsibilities of our internal team members.

    A1) Figure 31 is meant to protect the load under input reverse supply condition (0V to VIN and 48V to GND). If you want to use ORing for -ve rail, consider lm5051, TPS23521 device

    A2) D3(SS16T3) is to block current into LM5050 under input reverse supply condition.

    A3) As Vin (GND 0V) is at higher potential than ground (-48V) is your configuration, it can be used.

    A4) EVM supports 15A load. To evaluate for higher currents, use low Ron FET and if needed forced air cooling for evaluation purpose.

    Best regards, Rakesh 

  • 0 in reply to Rakesh
    TI__Genius 13278 points

    Rakesh,

     

    Thank you for your responses.

     

    For Q1, Figure 31 is wrong, Vin should be 0V and GNG should be 48V, right?

    Does TI have a plan to correct Figure 31 in the next datasheet update timing?

     

    Best regards,

     

    K.Hirano

  • 0 in reply to Kazuhiko Hirano
    TI__Guru** 103876 points

    Hi Hirano-san

    For Q1, Figure 31 is wrong, Vin should be 0V and GNG should be 48V, right?

    Yes

    Does TI have a plan to correct Figure 31 in the next datasheet update timing?

    Sure, we will plan to update with Vin=0V & GND = 48V in the datasheet revision update.

    Best regards, Rakesh