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TPS65132W How to expand Vpos start-up time?

Wataru Ito
Prodigy 510 points

Hi team

Is there any way to expand of TPS65132W's Vpos start-up time?

 

Our customer wants to adjust Vpos/Vneg start-up time as following.

This requirement come from LCD-module specifications.

  Vpos : more than 500usec

  Vneg : more than 1ms

According to DS,  start-up time is 500us(Typ.). So customer worried about that there is a possibility to dip from 500us in Min. condition.

Best regards,

Wataru Ito

  • 0
    TI__Expert 8010 points
    Hello Wataru-san,

    If the enable pin is set high the boost-converter will ramp up regulated (soft-start) independent of the output capacitor. This means that by changing the REG cap you will not change the ramp up time of the boost converter. It is not completely clear to me what the power-up sequence is for these rails. Do you mean that both rails have to start simultaneously but with different ramp times?

    The sequencing of the output rails is programmable. If you mean that after VPOS starts 500 us need to elapse before VNEG can start then you can easily program this, see chapter 9.2.3.2.1 of the d/s:
    You can e.g program the DLYP1 = 500 us.

    Please share the rough sequence requirements.

    Thank you.
    Best Regards.
    Ilona
  • 0 in reply to Ilona
    TI__Prodigy 510 points

    Hi Ilona-san,

    Attached please find the Customers requirements start up sequence.

    And customer tried add Cout capacitor to the Vpos but it could not expand Vpos ramp-up time.

    Is there any way to expand  Vpos ramp-up time?

    Best regards,

    Wataru Ito

    TPS65132W Vpos Rise Time_161111.xlsx

  • 0 in reply to Wataru Ito
    TI__Expert 8010 points
    Hello Wataru-san,

    Can you please try to attach the requirement once more. The file is corrupted and not readable.

    Thank you.
    Best REgards.
    Ilona
  • 0 in reply to Ilona
    TI__Expert 8010 points
    Note:

    The minimum ramp-up time of the positive rail (10% to 90%) is in the range of 420 us to 1 ms.
    The maximum startup current for the negative rail is 15 mA (smartphone mode) and 30 mA (tablet mode). According ramp-up time needs to be calculated by means of the formula of chapter 8.3.5.2 on page 15 of the d/s.

    Best Regards.
    Ilona