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Recommendation for Boost Charger

Khoi Ly
Prodigy 250 points
Other Parts Discussed in Thread: BQ25505, TPS61033

Dear E2E,

I am struggling with coming up a design that allows me to use a low-voltage source (1.9V) to charge a lithium-ion battery (3.7-4.1V).

What I have done so far was using a boost converter (U1V11F5 from Pololu) to boost the voltage from 1.9V to 5V, then connect it's output to a lithium ion battery charging board (TP4056). 

Here is what I observed:

1. The power supply (1.9V 0.88A) is connected to the booster.

2. The booster voltage is measured to be 4.05V when it is connected to the charger (even though it shows 5V when it is disconnected from the charger)

3. Charger output voltage is 3.851 V (when connected to the battery). The current drawn is 25mA.

So, I have a few questions:

1. The booster claims 70% or above efficiency for load under 1A and 2V input to get 5V output, which we satisfy in this case. So I wonder why it draws 1.67W of power and deliver only 0.1W? Does this have anything to do with maximum power tracking point?

2. Are there any boost charger in the market that can accept 2V in with approximately 800mA of current to charge the battery I have?

Thank you very much,

Khoi Ly

  • 0
    TI__Expert 8895 points

    Hi Khoi,

    I can't answer your question on U1V11F5 and TP4056 since it's not our products. And I don't know what you mean by maximum power tracking point since Iim not sure where your PV panel is applied.

    About the Boost recommendation, TPS61033 can accept 1.8Vin and output over 800mA. But if you requires a MPPT device, you can try bq25505.

    Best Regards,

    Travis