• State Resolved
  • Replies 7 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 98 views
  • Users 0 members are here
Support feedback
Options
Options
Related

TPS5430: TPS5430 cann't start

zhou zhx
Prodigy 30 points
Part Number: TPS5430

Tool/software:

The power supply circuit I designed using TPS5430 cannot start correctly when the supply current is below 800mA, regardless of the voltage, but it can start correctly when the current exceeds 900mA. What can I do to solve this problem (given the current design of the circuit)?

  • 0
    TI__Genius 14286 points

    Hello Zhou

    Could you please share some waveform which hep describe the issue you are facing. Kindly probe following points 

    1. PH
    2. VOUT
    3. BOOT

    It would really help if you could capture these waveforms at 700mA load and 1A load. Let me know Vin, Vout conditions and kindly share your schematic for review.

    Thank you

    Regards

    Onkar Bhakare 

  • 0 in reply to Onkar Bhakare
    Prodigy 30 points

    Here my load is not 700mA and 1A, my load is 5V/3A. It cannot start normally, which is due to the 800mA current at the input (Vin) preventing normal startup. Both 12V/800mA and 24V/800mA inputs cannot start normally. It is just that the input end requires a higher startup pulse current, but the source end limits the current to 800mA, which prevents the DC/DC from starting.

  • 0 in reply to zhou zhx
    Prodigy 30 points

    This is 24V Input setting 800mA current limiting，The DC/DC converter is not working properly. Probe 1 is BOOT，Probe 2 is PH（SW），Probe 3 is OUTPUT （5V）

  • 0 in reply to zhou zhx
    Prodigy 30 points

    This is 24V Input setting 1A current limiting，The DC/DC converter is  working properly. Probe 1 is BOOT，Probe 2 is PH（SW），Probe 3 is OUTPUT （5V），Normal work actual input 360mA/24V.

  • 0 in reply to zhou zhx
    TI__Genius 14286 points

    Hello Zhou

    As you correctly identified, the issue is likely your power supply’s 800mA current limit. Buck converters can demand higher initial current during startup to charge the output capacitor and supply load component 

    Let’s calculate the expected input current:

    • Output Power (Po): 5V * 3A = 15W
    • Efficiency (η): Let’s assume 80% (0.8)
    • Input Power (Pin): Po / η = 15W / 0.8 = 18.75W
    • Input Voltage (Vin): Assuming 12V
    • Input Current (Iin): Pin / Vin = 18.75W / 12V = 1.5625A

    Therefore, the issue is likely a limitation of your power supply, rather than a device issue. Your power supply must provide current higher than required, especially during startup.

    Thank you

    Regards

    Onkar Bhakare

  • 0 in reply to Onkar Bhakare
    Prodigy 30 points

    What methods can I use to delay the startup of the DC/DC in this design?

  • +1 in reply to zhou zhx
    TI__Genius 14286 points

    Hello Zhou

    Delaying the startup won't help here as even in steady state, current requirements from input side is 1.5625A. So, input power has to supply required current demanded by the converter

    Thank you

    Regards

    Onkar Bhakare