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tps61087 2.5V to 18V/200mA converter

vijay korat
Prodigy 20 points
Other Parts Discussed in Thread: TPS61087

 i have made tps61087 ic based dc-dc converter.

input range is 2.5V to 5V and output is 18V / 200mA.

when i give input from Duracell(two cell in series to make 3V) or 5V from CPU-SMPS dc -dc is working fine.load taking 100mA in working condition.

but when i give input 3.3V from SMPS, output is 18V in open condition.when i connect load voltage become 14V-15V and load is not working.

please help me to solve this problem.

  • 0
    Prodigy 20 points

    i have made tps61087 ic based dc-dc converter. input range is 2.5V to 5V and output is 18V / 200mA. when i give input from Duracell(two cell in series to make 3V) or 5V from CPU-SMPS dc -dc is working fine.load taking 100mA in working condition. but when i give input 3.3V from SMPS, output is 18V in open condition.when i connect load voltage become 14V-15V and load is not working. please help me to solve this problem.schematic is attached with this.

    TPS61087 design.pdf
  • 0 in reply to vijay korat
    TI__Guru 67475 points

    Hello Vijay,

    Do I understand your pdf correct that you changed the compensation components according the values you added in the yellow box?

    Please try if the power supply works when you use the compensation components used in the Evaluation Module design of TPS61087. The values you have in the yellow box most probable lead to an instable output.

    I think the input impedance of the batteries is high compared to the input impedance of the power supply and this seem to stabilize the design somehow, but it should work with the power supply as well.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Prodigy 20 points

    Hello Brigitte,


    As per your suggestion i change compensation network 16k and 3nf,still problem is there.

    when i give 3.3v from smps(of CPU) output voltage is 18V in open load condition but in loaded condition voltage become 14V.

    when i give input 3V(from two Duracell in series) its working and voltage is not changing load taking 18V / 100mA.

  • 0 in reply to vijay korat
    TI__Guru 67475 points

    Hello Vijay,

    The only idea I have is that your SMPS is limited in power. Please check the maximum output current of your power supply. For 18V/100mA, you need an input current of roughly 600mA. Maybe the CPU SMPS is limited in current.

    Best regards,
    Brigitte