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TPS63000: About UVLO trigger time

Tsukui Yusuke
Guru 21930 points
Part Number: TPS63000
Other Parts Discussed in Thread: TPS63802

Hi,

Could you tell me about TPS63000 UVLO spec?
Input voltage drops momentarily in customer application.
With that background, please tell me the time when UVLO is triggered.



Regards,
Yusuke

  • 0
    TI__Expert 7925 points
    Hi Yusuke-san,

    Could you please clarify the conditions your customer has? There is a short voltage drop and you want to know if UVLO will be triggered and how fast it will react?

    Best regards,
    Milos
  • 0 in reply to Milos
    Guru 21930 points

    Milos-san,

    Thank you for your support.
    〉There is a short voltage drop and you want to know if UVLO will be triggered and how fast it will react?
    →Yes.

    〉Could you please clarify the conditions your customer has?
    →Normal operation condition is Vin=1.8V to 3.6V , Vout=2.1V.
       Input voltage source is a dry battery.
       The voltage dip spec is "1.5V with 1 msec pulse".
       Occasionally the output voltage drops.
       For this reason, customers want the information and countermeasure.


    Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    Guru 21930 points

    Hi Milos-san,

    Sorry for rushing you but please let me know if you have any updates.

    Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Expert 7925 points

    Hi Yusuke-san,

    Sorry for the delay. If I understood correctly, the input voltage drops to 1.5 V, for the duration of 1 ms. If so, this pulse duration is too long, the UVLO will be triggered and turn off the device. Here are two examples:

    Vin=1.8 V, Vout=2.1 V, Iout=0 mA:


    Vin=1.8 V, Vout=2.1 V, Iout=50 mA:

    There is no easy workaround, the device simply cannot operate at Vin=1.5 V. If this voltage drop is caused because the battery is not strong enough, then you either need a stronger battery, or enough input capacitance to cover the load spike for a short time.

    Best regards,
    Milos

  • 0 in reply to Milos
    Guru 21930 points

    Milos-san,

    Thank you for your kind support.
    I understand.

    Let me ask you one more thing.
    Does a dip in the order of μsec cause Vout to drop?
    Please tell me the pulse width that does not detect UVLO.
    Customer want that information to add input capacitance.

    Best Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Expert 7925 points

    Yusuke-san,

    The UVLO circuit is triggered on falling edge. When Vin goes below Vuvlo (typ. 1.7 V, see section 6.5 of the datasheet) the device will restart. Therefore, avoid any Vin pulses that go below Vuvlo, the pulse width is not important. 

    What is causing the battery voltage to drop? Is it the load connected to the output of the TPS63000? In that case, calculate the input capacitance to be large enough to support the current demand so that the input voltage does not drop below Vuvlo.

    Best regards,
    Milos

  • 0 in reply to Milos
    TI__Mastermind 20900 points

    Yusuke-san,

    Do you have an update on the questions from Milos?

    TPS63802 might be a good alternative part. The Vuvlo for this part is at 1.25V. This is low enough that the Vin drop does not cause a converter shutdown.

    I will close the thread for now. Please post back or open a new post if there are further questions.

    regards,

    Julian

  • 0 in reply to Julian Hagedorn
    Guru 21930 points

    Milos-san, Julian-san,

    Thank you for your kind support.
    Could you tell me the release schedule of TPS63802?

    Best Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 20900 points

    Yusuke-san,

    TPS63802 planned release is October 2019.

    regards,

    Julian