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TPS51285B / Is it possible for Ch1 to output 5V under Vin=5.2V?

Guru 29710 points

Hi TI members,

Is it possible for Ch1 to output 5V under Vin=5.2V?
I heard input voltage of my customer's application can drop as low as Vin=5.2V.

I found the following figure however I can't decide if it is possible to output 5.0V under Vin=5.2V.



If the answer is no, I would also like to know the minimum input voltage that is capable of 5V output (Ch1).
Your advice would be really appreciated.

Best Regards,
Yaita / Japan disty

  • Hello Yaita-san,

    I think it can output 5V if Vin 5.2v, BUT Beacuse as we know, there is minmum off time limited  cause the switch frequency limited, So if VIN is only 5.2, the Fsw maybe will be limited below 120KHz, then  bandwith will be very narrow, I think the performance maybe not very good, even not stable at heavy loading or transient reponse, i suggest Vin not below 6v at least, then FSW can get around 300KHZ. of course above 7V is recommended.

    Regards,

    Yuchang

  • Hi Yuchang-san,

    Thank you for your support. I understood.

    I would like to ask one more.
    Is there variation data of switching frequency (Fsw) under Vin=5.2V, Ta=25℃?
    I would like to know if the data is available or not in simulation.


    My customer wants to know the data just as a reference.

    Best Regards,
    Yaita / Japan disty

  • Yaita-san,

    Actually I just wanted to attach this picture for your reference but failed.
    Yes, I think you can refer to the fig23.

    Regards,
    Yuchang
  • Yuchang-san,

    I aologize my request was unclear..

    Figure 23 shows Fsw of only one typical sample.
    Do you have the data that shows variability of Fsw between samples under Vin=5.2V, Ta=25℃?
    My customer wants to know the variability of Fsw under Vin=5.2V, Ta=25℃. 

    I would also like to know if the data is available or not in simulation.

    Best Regards,
    Yaita

  • Yaita-san,

    Sorry, you mean customer want to get the variability of Fsw under Vin=5.2V, Vout=5V at Ta=25℃?
    I am not sure if we have. but let me check, maybe need take one or two days.

    Regards,
    Yuchang
  • Yuchang-san,

    Yes! I mean it.
    I really appreciate if you confirm the request.

    Best Regards,
    Yaita

  • Yaita-san,

    Sorry, I checked but couldn't find the data.

    Datasheet Fsw&Input curve is based on EVM test. and different system maybe gets different Frequency variety.

    Regards,

    Yuchang

  • Hi Yuchang-san,

    Thank you for your confirming.
    I understood.

    Best Regards,
    Yaita