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TPS61022EVM-034: TPS61022EVM-034: Efficiency is too low.

Katherine Armitage
Prodigy 40 points
Part Number: TPS61022EVM-034
Other Parts Discussed in Thread: TPS61022

Hi,

I am testing with the TPS61022EVM in preperation of using the TPS61022 in a design.  

I am testing ultra low power mode and I am seeing efficiencies in the low 80% instead of the 90%.

I am using a power supply to supply Vin and a constant current load of 5mA.  My results are below.  I expected to see higher efficiencies.  Are there things I need to do to improve the efficiencies at low power mode?

Vin Cin (mA) Vout Cout* (mA) Eff (%)
4.2 7.22 5.188 5 0.855428
3.7 8.31 5.188 5 0.84366
3.2 9.64 5.19 5 0.841221
3 10.4 5.189 5 0.831571
2.5 12.68 5.185 5 0.817823
2 16.3 5.182 5 0.794785

Thanks

  • 0
    TI__Mastermind 34201 points

    Hi Katherine,

    Thanks for reaching out.

    1. Firstly, did you put the MODE pin jumper to GND so that TPS61022 is working at PFM mode at light load condition. 

    2. Is this the original EVM? Did you change any components?

    3. For the efficiency measurement, please use current DMM to measure input and output current because the power supply and E-load monitor is not accurate enough at this ~mA range according to our experience. Also measure the input and output voltage with DMM at EVM Vin_sense and Vout_sense jumper because the power cable also has voltage drop.

  • 0 in reply to Zack Liu
    Prodigy 40 points

    Hi Zack,

    1. Yes the MODE pin jumper is set to GND.

    2. When I took these measurements I did not change any components.

    3. I am already using a DMM to measure the source current.  I did not use a DMM at the Vin_sense and Vout_sense jumper.  I will do so, but my cables are fairly short and since my current is already being measured I'm not sure how much a more accurate measurement on the voltage will show.

    Other than that is there any other method to improve the efficiency?  Would reducing the inductor value help or increasing the resistors?  My current is very low.  I am looking at 5mA load current (set with a constant current load).  Is there anything specific I need to do to for low current?

    Thanks

    Katherine

  • 0 in reply to Katherine Armitage
    TI__Mastermind 34201 points

    Hi Katherine,

    Understood.

    Measuring the Vin_sense and Vout_sense with DMM will increase the efficiency. Our datasheet efficiency curve is measured with this meathod.

    May I know the maximum load current, Vin range, Vout of your application? TI has some low-Iq, high efficiency boost converter devices. I may find a more suitable one for you.