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LM4041-N: About Vref/Vz(Vka) characteristic

teritama
Expert 2410 points

Part Number: LM4041-N

Tool/software:

Hi team,

We want your opinion about below added explanation in new revision detasheet of LM4140-N.

  

"When the output voltage, VZ, is set below 2.5V on adjustable versions of LM4041-N and LM4041-N Q1, the device can experience increased reference voltage change with output voltage change (ΔVREF/ΔVKA) when compared to output voltages set equal to or above 2.5V"

Q1. In this explanation, Vz is same meen with Vka?

Q2. In LM4041-N datasheet, the characteristic of ΔVREF/ΔVKA is wote as ΔVREF/ΔVZ. Is this understanding correct?

       In other datasheet(LM4041), ΔVREF/ΔVKA is defined by Iz. However, in LM4041-N, ΔVREF/ΔVZ is defined by IR like below figures.

  

                                        LM4041                                                                                   LM4041-N

      Is there any differens between these characteristic?

Q3. In above explanation, in my understanding, when Vz is set below 2.5V, reference voltage change is increase larger than Vz is above 2.5V.

    Is it correct that reference voltage change increase is max -3V as wrote in Electrical Characteristic in datasheet in Vz is below 2.5V condition?
    Or in this condiition, reference voltage change is over -3V?

Please your opinion about above.

Best regards,

teritama

  • 0
    TI__Expert 5770 points

    Hi Teritama

    Thanks for your question!

    1. Vz is the same as Vka. This value is the voltage at the cathode of the device.

    2. ΔVREF/ΔVo and  ΔVREF/ΔVKA are both the reference voltage change with output voltage change. This is represents the same specification, and I_R and I_Z are also the same.

    3. Let me double check this question with the team and get back to you tomorrow.

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    TI__Expert 5770 points

    Hi Teritama,

    Thanks for your patience!

    3.

    That is correct. When Vz is set below 2.5V, the reference voltage change increase is larger than when Vz is above 2.5V.

    The condition with -3mV/V is the condition for when Vz > 2.5V.

    I hope this helps!

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    Expert 2410 points

    Hi Andrew-san,

    Thank you for checking.

    I understood that when Vz<2.5V, reference voltage change is out of max range( below -3mV/V).

    Do you have any data of max ΔVREF/ΔVo when Vz=Vref~2.5V?

    Best regards,

    teritama

  • 0 in reply to teritama
    TI__Expert 5770 points

    Hi Teritama,

    Let me double check with the team and get back to you tomorrow.

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    Expert 2410 points

    Hi Andrew-san,

    Thank you for double chackeing. Do you have any update with this?

    Best regards,

    teritama

  • 0 in reply to teritama
    TI__Expert 5770 points

    Hi Teritama-san,

    Thanks for your patience.

    When Vka = 2.5V, the spec is met both at room and across temp.

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    Expert 2410 points

    Hi Andrew-san,

    Thank you for update.
    Thank you for update. Do you mean ΔVREF/ΔVo won't be out the spec of below in the case of room and whole temp and Vka=2.5V?

    Best regards,

    teritama

  • 0 in reply to teritama
    TI__Expert 5770 points

    Hi Teritama-san,

    That is correct. For Vka = 2.5V, the spec shown is met across temp.

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    Expert 2410 points

    Hi Andrew-san,

    Sorry for my typo, is your answer same with in the case of room and whole temp and Vka "<" 2.5V?

    In the datasheet, this spec is defined in Vref<Vz<10V. The customer is concerning that in below 2.5V condition, change of reference voltage can out of range the datasheet from below sentence.

     "When the output voltage, VZ, is set below 2.5V on adjustable versions of LM4041-N and LM4041-N Q1, the device can experience increased reference voltage change with output voltage change (ΔVREF/ΔVKA) when compared to output voltages set equal to or above 2.5V".

    Best regards,

    teritama

  • 0 in reply to teritama
    TI__Expert 5770 points

    Hi Teritama-san,

    Thanks for the update!

    Unfortunately, we do not have this specific data for Vka < 2.5V.

    We can only offer the condition with -3mV/V is the condition for when Vka > 2.5V, and this reference voltage change increase is larger than when Vka is above 2.5V.

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    Expert 2410 points

    Hi Andrew-san,

    Thank you for the answer. I understood.

    For reference, do you have any information about Vka<2.5V case in actual cases in the market?

    We assume that there were actual cases in the market as the reason for adding this statement in the datasheet. I would like to know what ΔVREF/ΔVo values were obtained under what conditions in actual cases as reference information.

    And you said that you have the data in case of Vka>2.5V only, do you have any plan of change the test condition wrote in datasheet electrical characteristic from "Vref<Vz<10V" to "2.5V<Vz<10V"?

    Best regards,

    teritama

  • 0 in reply to teritama
    TI__Expert 5770 points

    Hi Teritama-san,

    Let me check with the team and get back to you with a response early next week.

    Best Regards,

    Andrew Li

  • +1 in reply to Andrew Li
    TI__Expert 5770 points

    Hi Teritama-san,

    Thanks for your patience.

    We have received no customer complaints about this use case, and we will approach datasheet changes as necessary.

    Best Regards,

    Andrew Li

  • 0 in reply to Andrew Li
    Expert 2410 points

    Hi Andrew-san,

    Sorry for reply and thank you for kindly supports.

    I understood.

    Best regards,

    teritama

  • 0 in reply to teritama
    TI__Expert 5770 points

    Hi Teritama-san,

    If you have no further questions, I will close this thread. To reopen this thread, simply reply to this message!

    Best Regards,

    Andrew Li