• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 64 subscribers
  • Views 464 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

Most TPS-series buck converters top out at 6Vin(max) on recommended operating conditions, so what to do when using 4 x AA alkaline cells?

D Guillot
Prodigy 150 points
Other Parts Discussed in Thread: TPS62240, TPS62172, TPS62740

My handheld portable application uses 4 x AA alkaline cells and needs 3.3V regulated output and well under 300mA draw. Would like to get "light-load" efficiency.

When AA alkalines are "fresh" they put out up to 1.6V, so I'm looking at 6.4V as source. Must have an ENABLE input.

The TPS62240 looks ideal, except for this problem.

Any suggestions?

Thanks!

  • 0
    TI__Intellectual 1460 points

    Hi Guillot,

    You can use TPS62172.This works from minimum 3V to 17V.It can handle currents upto 500mA.It has enable pin along with power save mode .

     

    Another option is TPS621XX series which takes 2.5V to 9V .It can handle upto500mA current.It also has enable pin and power save mode to boost efficiency at light load.

    But it is a old part so will be costly.

    I hope this helps.

    Regards,

    Harmeet

  • 0 in reply to Harmeet Singh
    Prodigy 160 points
    The problem with the TPS62172 is that its efficiency at light loads isn't that great. My application will also use 4 series alkaline batteries and mostly be in a sleep state using only 10uA. Per Figure 7 in the TPS62172 datasheet, for 3.3V out and 5V in the efficiency at 100uA is about 65% and heading down. Could be much worse at 10uA load current. I was looking at the TPS62740 because it can maintain 90% efficiency down to 10uA. That would be ideal, but it's only specified to Vin up to 5.5V and 6V absolute max. Any other suggestions?