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TLV61220: TLV61220 not generating 3.3V

Daniel Wirick
Prodigy 30 points
Part Number: TLV61220

Been working on this a few days, but no progress.  I'm trying to boost a single AA battery to 3.3V

The main recommendation in the issues I've researched is the output capacitor, so I tried soldering one across the IC.

Inductor I'm using is NR3015T4R7M.  I have also tried NRS4012T100MDGJ

I have tried without Q3 and a short in it's place.

I have tried shorting enable to Vin.

I've tried with and without a load attached.

I've tried multiple PCBs.  They act the same.

I've referenced the following E2E issues on this subject:

TLV61220: Vout can't reach 3.3V

TLV61220 Boost circuit Issue

TLV61220: Vout can't reach 3.3V for Vin from 1.5V to 3V

TLV61220： TLV61220 output problem(Iout 20ma+)

TLV61220 boost circuit doesnt work

 

Vin:


 

Enable:


 

Feedback:


 

Switch:

 

Vout:


 

Ground:


 

 

Schematic:


 

Layout:


 

I've probably missed something simple, but better to ask for help at this point.  Thanks!

  • 0
    TI__Mastermind 21565 points

    HI Daniel:

    The layout is not good, but I'm not sure if it's the root cause. 

    May you short the EN to Vin, and then catch the waveforms of Vin, SW in same time?

    Do you have DC power supply? Try a higher Vin.

  • 0 in reply to Minqiu Xie
    Prodigy 30 points

    Yea, sorry the layout is junk.  My adjustable power supply is in a different building ATM, but I ran a test with 2 AA.  The result is that it works with no load, but not under a 1k ohm load.  Vin is about 2.85V now.  Vout is 3.3V with no load, 2.5V off, and 2.15V turned on with a 1k load.  The setup I tested has the 10uH inductor and 20uF output capacitance soldered directly across the IC.  I tried with Enable shorted, and with the switch but it made no difference.

  • 0 in reply to Daniel Wirick
    Prodigy 30 points

    After a lot of prayer and a re-layout of the design I found the problem this morning.  I went to fab the new design and noticed that the 3rd party inductor footprint has the "keepout" area in the copper layer.  This resulted in small trace shorts across the inductor!  I cut them out with my xacto and bingo! the regulator works as advertised.  Thank you Jesus!  Sorry for bugging you guys, and hope you can learn from my hard lesson.

  • 0 in reply to Daniel Wirick
    TI__Mastermind 21565 points

    Hi Daniel:

    Glad to such good news.

    Thanks for your kind words. And it's my pleasure to support you.

    :-)