• State TI Thinks Resolved
  • Locked Locked
  • Replies 9 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 442 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS62808: TPS62808YKAR

Lisa George
Prodigy 90 points
Part Number: TPS62808
Other Parts Discussed in Thread: TPS7A21, TPS7A03, TPS7A02, TPS7A05

Hi,

I would like to know the whether LDO (TPS7A2133BPYWDJ) or Buck (TPS62808YKAR) performs well with a Battery(Lithium Thionyl Chloride Battery) operated device that has voltage of 3.6V. The ultimate aim is to step down voltage from 3.6V-3.3V. I would like to know efficiency comparison of both also.

Kindly reply!

  • 0
    TI__Genius 16030 points

    Hello Lisa,

    Thank you for using E2E,

    TPS62808 has operating quiescent current of 2.3-µA, while TPS7A21 has 6.5-µA. I didn't find the efficiency data for TPS7A21 in the datasheet, I can provide you the efficiency data of TPS62808 with your operating conditions by end of the day. Later I can reassign the thread to respective product line of  TPS7A21, they can help you regarding the efficiency of the device.

    Is the efficiency the main criteria or do you have any other requirements?

    Thank you & regards,

    Moheddin.

  • 0 in reply to Moheddin Pasha Shaik
    Prodigy 90 points

    Hello,

    Thank you for your reply. I also couldn't find the efficiency of the LDO from the datasheet but the efficiency of buck is mentioned in the datasheet. 

    Efficiency is the main criteria for battery operated devices. So I need to consider that.

  • 0 in reply to Lisa George
    TI__Genius 16030 points

    Hello Lisa,

    Thank you for the information. Please find the efficiency measurements of TPS62808, Vin =3.6V, Vout=3.3V, temp =25°C. 

    The measurements are performed by using EVM(TPS62806-7-8EVM083 Evaluation Module)

    Thank you & regards,

    Moheddin.

  • 0 in reply to Moheddin Pasha Shaik
    Prodigy 90 points

    Thank you!

    Could you please check the efficiency of LDO (TPS7A2133BPYWDJ) ?

  • 0 in reply to Lisa George
    TI__Genius 16030 points

    Hello Lisa,

    Lisa George said:
    Could you please check the efficiency of LDO (TPS7A2133BPYWDJ) ?

    I assigned the thread to respective product line, they will answer you soon.

    Thank you & regards,

    Moheddin.

  • 0 in reply to Lisa George
    TI__Mastermind 32985 points

    Hi Lisa,

    The efficiency of the LDO is defined as:

    (Vout * Load Current) / (Vin * (Load Current + Quiescent Current) )

    The quiescent current of the TPS7A21 is 6.5 uA typical.  How much current do you need?  If you do not need more than 200 mA, you may wish to consider the TPS7A02 (25 nA quiescent current), the TPS7A03 (200 nA quiescent current) or the TPS7A05 (1 uA quiescent current).  In general, at light loads an LDO will be more efficient.  At heavy loads the switching converter will be more efficient. 

    Notice I am going down to 1uA in this plot.  If you have a load under 100nA, keep in mind that the leakage from your input and output capacitors will play role in your efficiency as well.

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    Prodigy 90 points

    Hi Stephen,

    My current requirement is 150mA.

  • 0 in reply to Lisa George
    TI__Mastermind 32985 points

    Hi Lisa,

    Will you need an input filter for the switching converter? If so then that will drop some additional power and that will slightly lower the efficiency of the switching converter option.  How much it will lower it, will depend on the filter you insert into your design.

    I would look at the TPS7A02/3/5 LDO options and compare that with the TPS62808 switching converter option.  If you need to operate closer to 150mA most of the time, then the switching converter may offer higher efficiency.  If you need to operate at light loads most of the time, then the LDO will offer higher efficiency.  If you need the smallest cost or the smallest solution size, the LDO will be your best option.

    Thanks,

    Stephen