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Simulation result on TPS2500

TARO
Prodigy 50 points
Other Parts Discussed in Thread: TPS2500, TPS2501

Dear Sir or Madam

 

I simulated circuit with TPS2500DRCR on test board  with no load (see circuit diagram in attached file). My result (see Fig upper left in the attached file) is battery voltage decrease 60mV with increasing battery current 300mA periodically 22Hz to 24Hz.  Also I simulated circuit adding resistor (100 Ohm) between battery and inductor, and confirmed it does not appear (see Fig left below in the attached file).

1. I can not understand why TPS2500 needs 300mA of current periodically.
2. Is there any solution to solve it?

8765.waveform.pdf

6523.circuit_diagram.pdf

  • 0
    TI__Mastermind 42795 points

    At light loading the TPS2500 boost converter enters ECO or PFM mode operation (see pg 12 bottom of datasheet). When in this mode, the converter will periodically (depends on how light the VAUX loading is start switching to keep the AUX capacitor charged. The switching can cause this input current pulsing. At heavier AUX loading, the converter will run continuously to maintain a steady input average current.

    Placing the resistor in series with the inductor might fool the PFM circuitry, but is not a good solution (because it limits the AUX output power available). Increasing the input capacitance can reduce the current pulse amplitude but won't totally eliminate it.

  • 0 in reply to Eric Wright
    Prodigy 50 points

    Dear Eric,

    Thanks for the prompt reply.  I will try to increase the input capacitance to reduce the current pulse amplitude.

    When we have further questions, "Hide" who is an engineer will send it to community site again.

    Thanks,

  • 0 in reply to TARO
    TI__Prodigy 650 points

    TARO,

    If you don't like the light load mode of TPS2500, you can try TPS2501, only difference is TPS2501 is fixed switching frequency.

    TPS2501 has higher switching lost in light load, but customer usually uses the EN pin to shut it down during no load.

    Look like you are using TPS2500 in single cell battery application. TPS250x is perfect part for one cell battery boosting to 5V rail. The USB output integrated power switch function inside. And with 500mA to 1A load, its efficiency can be up to >91%.

    Vincent Wang.

  • 0 in reply to Vincent Wang64858
    Prodigy 50 points

    Dear Vincent Wang,

    Thanks for your information and explanation.

    I will try TPS2501.

    Thanks again.

    Taro