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LM5069: TIDA-00233 Operation under negative input

na na78
Guru 16770 points
Part Number: LM5069
Other Parts Discussed in Thread: TIDA-00233, , TPS2660, LM5050-1, LM74700-Q1

Hi

I refer TIDA-00233.

I want to see circuit behavior under negative input.

(Especially, confirming a state that the input can not reach output side.)

If I suppose that the -30V is applied at J1, does the input of LM5069 act like following simulation?

Sim.xlsx

BestRegards

  • 0
    TI__Guru** 103706 points
    Hi,

    Yes, the circuit will block reverse input voltages reaching at the output side.
    Can you share your system requirements and end product. What is your max load current?

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Guru 16770 points
    Hi Rakesh

    Thank you for your reply.

    App is PLC.
    And load current is ~3A.

    The customer considered two TPS2660 used in parallel, but TPS2660 offers 150mohm as Ron.
    It would be equal to 75mohm as parallel. Ron of FET is smaller than TPS2660.
    They want to avoid heat as possible.

    BestRegards
  • 0 in reply to na na78
    TI__Guru** 103706 points
    Hi,

    Ok. Got it.
    TIDA-00233 can be used to meet low Ron requirement and to lower power loss.

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Guru 16770 points

    Hi Rakesh

    Thank you for your reply.

    Could you please answer the additional questions?

    1.

    LM5050-1 offers a circuit for the reverse input voltage protection.

    Our customer says that they tested this circuit with Vin=-30V and they saw negative voltage lower than -0.3V at Vout.

    There is step down converter which has -0.3V as absolute maximum ratings, so this configuration had not been acceptable.

    Could it be possible that the same issue would occur with TIDA-00233?

    2.

    Is it possible to use LM74700-Q1 instead of LM5050 in TIDA-00233?

    The customer says LM74700-Q1 (sample) provided good result for negative input voltage, so we want to consider the use of LM5069 and LM74700-Q1 like TIDA-00233.

    BestRegards

  • 0 in reply to na na78
    TI__Guru** 103706 points
    Hi,

    1A> We can expect similar behavior of LM5050-1 even in TIDA-00233

    2A> Yes, LM74700-Q1 is good option. I suggest to proceed with LM74700-Q1 + LM5069 like TIDA-00233


    Best Regards,
    Rakesh