Paralleling TPS61025

Eren Deniz

Other Parts Discussed in Thread: TPS61025

Dear all,

I'm designing a mobile medical device (blood pressure monitoring device) which will have one, two or three alkaline batteries in series. Power consumption is about 300 mA maximum (Air pump). So tps61025 seems that it can source this curremt except the input has only one alkaline battery and the voltage is below 0.9 v.

As i understand that tps61025 can source 200 mA for 0.9 to 3.3 v.

So, is it possible to parallel two of tps61025's so that i can increase current output?

thanks,

eren.

over 11 years ago

0 Jasper Li over 11 years ago

TI__Mastermind 46905 points

I would not suggest to parallel two device directly, because of the current sharing problem.

thanks

jasper li

0 Jasper Li over 11 years ago

TI__Mastermind 46905 points

the 300ma is the peak current or average current? thanks jasper li

0 Eren Deniz over 11 years ago in reply to Jasper Li

Prodigy 30 points

Jasper, thanks for your reply.

when the air pump is inactive, the average current is about 20 mA, but the air pump consumes about 300 ma for 10 seconds for every one of the measurements. we can say that it will be active for 10 secs and inactive for about 10 minutes.

thanks

eren.

0 Jasper Li over 11 years ago in reply to Eren Deniz

TI__Mastermind 46905 points

Hi Eren

sorry but i don't have a solution for your application.

and just my curiosity, if Vin=0.9, Vout=3.3/300mA, the input current may reach 1.4A if considering 80% converter efficiency. this high input current current may cause large power loss in the battery (depending on the ESR of the battery). what is your solution of this problem.thanks

jasper li

0 Eren Deniz over 11 years ago in reply to Jasper Li

Prodigy 30 points

Dear Jasper,

thank you for your interest.

Regarding to current problem, i will have to use two batteries in series.

The battery i prefer to use (AA-2400 from Energizer) has only 30 to 40 mohms internal resistance and by using two of them in series will have 1.8 to 2.4 volts. So the current in input and output sides will be acceptable i think.

Thanks

eren

0 Jasper Li over 11 years ago in reply to Eren Deniz

TI__Mastermind 46905 points

yes, two batteries in series will be good.

thanks

jasper li

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Paralleling TPS61025