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TPS62140: TPS62140 / Fastest startup time

S.Satoshi
Guru 21685 points
Part Number: TPS62140
Other Parts Discussed in Thread: TPS62135,

Hi,

Please let me ask about fastest startup time. I understand that we can see fastest startup time when driving SS/TR pin with ideal fast pulse, then how can we estimate or calculate the fastest startup time?

Best Regards,

Satoshi / Japan Disty

  • 0
    TI__Expert 8420 points
    Hi Satoshi,

    Did you already take a look at equation (10) of the datasheet? According to the design specs the soft start cap can be calculates
    What is the customer requirement for start up time?
  • 0 in reply to Sabrina
    Guru 21685 points

    Hi Sabrina,

    I know that the soft start capacitor can be calculated by equation (10), but now they want to know the minimum start up time (disable soft start) just for their reference. From page 10 of datasheet,  fastest startup can be provided by leaving SS/TR pin un-connected, then I'd like to know this fastest startup time.

    Best Regards,

    Satoshi

  • 0 in reply to S.Satoshi
    TI__Guru*** 148780 points
    Hi Satoshi-san,

    This would need to be measured on an EVM. It also depends on whether you enable the device via applying Vin or applying EN. Can you share more details about your application and this SS time requirement?

    As well, the TPS62135/6 are newer, smaller, and more accurate. They state a 150 usec SS time when SS/TR is open.
  • 0 in reply to Chris Glaser
    TI__Guru*** 148780 points

    Here is the startup waveform of the default TPS62140 EVM without a SS/TR cap.  The same basic time was observed for both 12Vin and 5Vin, no load and 2A resistive load.  Vout ramps up in about 60 usec.  

    Blue = EN

    Red = Vout

    Yellow = PG

  • 0 in reply to Chris Glaser
    Guru 21685 points
    Hi Chris,

    Thank you for sharing start up waveform. The customer is considering the load device now so the detail of SS time requirement is not also fixed yet. This waveform should be enough so far.

    Best Regards,
    Satoshi