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TPS74801: TPS74801 application

Mark Chen52
Expert 7115 points
Part Number: TPS74801
Other Parts Discussed in Thread: TLV755P, TLV707P, TPS745

Hi All,

My customer would like to use TPS74801 for 4.5Vin, 4.5Vbias, 3.6Vout, maximum output current=0.2A application. could you help to confirm this application is ok or not? If not, could you explain the detail ?? do you have another recommend solution? how about TLV755Pcan be use?

  • 0
    TI__Guru 55940 points

    Hi Mark,

    The concern for your application is the risk of entering dropout due to Vbias being extremely close to the Vbias dropout.  We generally recommend that Vbias be equal to Vout + 1.6 V in order to ensure that the LDO has enough headroom on Vbias to ensure regulation.

    If you do not have a rail that is 5.2 V or above, another LDO should be used.  Unfortunately we do not have a 3.6 V output version of TLV755P released at this time.  TLV707P looks like it could be a good fit for your application.

    Very Respectfully,

    Ryan

  • 0 in reply to Ryan Eslinger
    TI__Expert 7115 points
    Thanks Ryan, about your attached picture, the Vbias dropout voltage should be equal to Vin-Vout, right? if output current is 0.5A, Vin=4.5V, vout should be equal to 4.5-1.1(dropout voltage)=3.4V, right?
    how about TPS745 for this application? looks like good fit for my application also, right?
  • 0 in reply to Mark Chen52
    TI__Guru 55940 points
    Hi Mark,

    Vbias dropout is Vbias - Vout; however, since Vbias is equal to Vin in your application, your statement does hold true for your application. I agree that based on the typical characteristics curves TPS74801 will typically fit your application requirements. I am simply pointing out that you are on the verge of Vbias dropout.

    TPS745 is another option that fits what you have told me about your application requirements.

    Very Respectfully,
    Ryan