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TPS61088: Which components affect the output capacity?

XY MA
Prodigy 20 points
Part Number: TPS61088

Hello, I built a 2.7V to 5V boost circuit based on the schematic provided by Power Designer. However, it can only output around 0.2A at most currently. I need it to output 5V 3A. Which components affect the output capacity?

  • 0
    TI__Mastermind 36590 points

    1.Inductance parameters
    The saturation current capability of an inductor directly affects the upper limit of the output current. If the inductor specifications are insufficient (such as low saturation current), it may result in limited output current or system instability. ‌
    2.filter capacitor
    The capacity and position of the output capacitor (such as whether it is far from the power circuit) will affect the dynamic response and ripple suppression capability. Insufficient capacitance or unreasonable layout can lead to insufficient transient response, affecting the stability of output current. ‌
    3.Feedback loop design
    The values of feedback resistance and capacitance directly affect the performance of PID regulation. Improper feedback parameters may cause dynamic response lag and limit the peak output current. ‌
    4.Thermal Design
    Poor heat dissipation can limit the continuous output capability of the chip under high loads. For example, prolonged full load may cause the chip to overheat, thereby reducing the output current.

    We suggest you take a look at the layout and BOM provided by Power Designer

  • 0 回复 Vivian Gao
    Prodigy 20 points

    First, after testing, I found that the voltage at the Vin pin dropped to 2.1V, and the waveform of sw disappeared. This should indicate that the under-voltage protection was triggered. Additionally, I noticed that after setting a normal output with a 1A load current, gradually increasing the load current still allowed for normal output, up to 1.2A. Please explain why the input voltage was pulled down. I added a 330uF capacitor before the inductor, but it did not improve the situation.

  • 0 回复 XY MA
    TI__Mastermind 36590 points

    What exactly is your schematic and how are the parameters of peripheral devices selected

  • 0 回复 Vivian Gao
    TI__Mastermind 36590 points

    If you are very confident that your selection and layout are correct, please test several boards or replace the chip to rule out issues with the chip itself and soldering

  • 0 回复 Vivian Gao
    Prodigy 20 points

    The schematic parameters, PCB layout and test waveforms are shown in the figure. I wonder if solving the problem of Vin being pulled down can also solve the output problem. I'm not clear why Vin is being pulled down. Is it because the inductor's DCR is too large or is it saturated? The inductor I chose has a saturated current rating of 28A. I think it should be sufficient.

  • 0 回复 XY MA
    TI__Mastermind 36590 points

    Insufficient load capacity of input power supply
    When the load is connected, if the rated power or current of the input power supply is insufficient, it will cause a voltage drop. For example, if the output impedance of a voltage regulator is large or the power reserve is insufficient, it cannot maintain stable output when the load increases.

    You use a DC source as the VIN instead of a battery as the VIN.

    The minimum input voltage on the schematic is 2.51V, but the minimum input voltage on the chip is 2.7V. 

    L3: DCR = 11 mΩ IDC = 9.4 A is enough.

    The resistors and capacitors used in other pins also do not match the webench power designer

    webench.ti.com/.../133