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LM5060: How should I apply Vin and Vout for Cases A-D?

R.Fukunaga
Expert 2485 points
Part Number: LM5060

Tool/software:

Hi all,

8.2.3.2 I have a question about Detailed Design Procedure.

How should I apply Vin and Vout for Cases A-D?

Vin=24 V (Max25 V) is supplied to LM5060. The voltage range varies in the range of 0~25 V. In this case, if Vin=0 V, Rsmin=0 Ω from (17).

Should I set the input to 0V and output to 24V?

I also checked the following calculation tool.

SLVC667 Calculation tool | TI.com

Minimum Input Operating Voltage: VIN(MIN)

Maximum Input Operating Voltage: VIN(MAX)

The values of recommended operating conditions are listed in each. 5.5V to 65V

Should I refer to this?

Best Regards,

Ryusuke

  • 0
    TI__Mastermind 39460 points

    LM5060 operating voltage is 5.5 V to 65 V. 

  • 0 in reply to Avishek Pal
    Expert 2485 points

    Hi Avishek,

    When considering Rdson (Ω) in the worst case,

    is it correct to understand that Vin (min) =5.5 V and Vin (max) =65 V should be calculated?

    Best Regards,

    Ryusuke

  • 0 in reply to R.Fukunaga
    TI__Mastermind 39460 points

    I am not able to understand your question. 

  • 0 in reply to Avishek Pal
    Expert 2485 points

    Hi Avishek,

    I’m sorry if my explanation was unclear.

    I have a question about section 8.2.3.2.1, “Reverse Polarity Protection With a Resistor.”
    When calculating Rs(min), which values of Vin and Vout should be used for substitutions in equations (16) through (19) in the datasheet?

    I noticed that the calculation method for Rs(min) differs depending on the case (Case A–D).
    For example, in Case A, it states that Vin is negative, but I am unsure what exact voltage to use for Vin when performing the calculation for Rs(min).
    In my application, I am supplying 24V (maximum 25V) to the LM5060, and the input voltage can vary between 0 and 25V. In this scenario, what value should I use?

    Could you please clarify which values should be substituted for Vin and Vout in each of Cases A through D?

    Best Regards,

    Ryusuke

  • 0 in reply to R.Fukunaga
    TI__Mastermind 39460 points

    I will respond to you by early next week. Please cooperate. I am on leave for next two days. 

  • 0 in reply to Avishek Pal
    Expert 2485 points

    Hi Avishek,

    Sorry for the additional question.

    ・Equations (18), (20), and (21)

    Equation (18) has two parameters, Ro (min) and Rs.

    Equations (20) and (21) include Rs and Ro, respectively.

    What are the fixed values of Rs, Ro, and Ro (min) to calculate?

    We decide and substitute a value that exceeds the min value calculated in Equations (16) and (17), and then use the calculated result as the resistance

    value.

    Is this understanding correct?

    Best Regards,

    Ryusuke

  • 0 in reply to Avishek Pal
    Expert 2485 points

    Hi Avishek,

    How is the progress?
    I made a request, so I would appreciate it if you could reply.

    Best Regards,

    Ryusuke

  • 0 in reply to R.Fukunaga
    TI__Mastermind 39460 points

    Equations (16): Maximum possible output voltage,

    Equations (17): Maximum possible input reverse polarity voltage,

    Equations (18): Maximum possible VOUT - VIN,

    Equations (19): Maximum possible negative VOUT voltage,

    R.Fukunaga said:
    Is this understanding correct?

    Please use the LM5060 design calculator to find out the appropriate value of Rs (Cell: F48 in the design calculator) considering the value of Ro and overcurrent fault detection threshold. 

  • 0 in reply to Avishek Pal
    Expert 2485 points

    Hi Avishek,

    1) For example, if Vin=24V is assumed, but ± may be connected in reverse,
    Vin is -24 V.

    ① If a negative voltage may be connected, refer to Case A.

    ② Input 24 V for Worst Case Reverse Polarity Voltage (Vin =-24 V).

    Is this correct?

    2) Equation 18 Equation 20 Equation 21 has 2 parameters, Ro (min) and Rs.

    When calculating Ro (min), what value should I input for Rs?

    8.2.3.2.2 Should I calculate a good resistance value considering Fault Detection With RS and RO?

    I can see the value of Rs when I input it into the formula, but how is it calculated?

    In short, I want to know which values I should input for Vin, Vout and Worst Case Reverse Polarity Voltage to use in this formula.

    SLVC667 Calculation tool | TI.com

    Best Regards,

    Ryusuke