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constant current buck PWM not working right? 2017-10-07T21:17:22+00:00

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  • rokenbuzz
    October 7, 2017 at 9:17 pm
    Post count: 0
    #22793 Reply |

    I have a model 090482 “DROK DC-DC4.5-30V to 0.8-30V Constant Voltage and Current Buck Converter 12V to 5V 5A Step-down Voltage Regulator Module Board LED Driver Power Transformer”
    I started with no PWM connected and set the desired voltage (5v) and current for powering my LEDs at the highest brightness I’d like.  They work fine.
    Then I connected my microcontroller’s PWM and ground, and connected ‘key’ to ground.
    Using PWM in my software, at 100% duty I see a voltage of 2.43v, and as I lower my PWM duty, the voltage drops proportionally.  I thought the voltage at full duty should be 5v, since that’s what I set the trimmers to be.  The PWM control does seem to be working, but the top voltage is always 2.43v.
    But no matter what adjustments I make on the trimmers, at 100% PWM duty I ALWAYS get 2.43v.
    If I disconnected my wires to Gnd/PWM/key, it’s back to working with a 5v output.  If I change it to 10v, and connect my microcontroller again, using 100% PWM duty still results in 2.43v.
    Shouldn’t 100% PWM duty be the full voltage I’ve set using the trimmers?
    Thanks for any help!
    rokenbuzz

    rokenbuzz
    October 17, 2017 at 1:25 am
    Post count: 0
    #23321 Reply |

    I am still at a loss with this.
    Drok, do you any advice whatsoever?  I’m stuck.

    Drok
    Keymaster
    October 17, 2017 at 8:53 am
    Post count: 2971
    #23324 Reply |

    Hello rokenbuzz,
    We are terribly sorry we just found we miss your message.
    Actually, this PWM control is not linear. PWM adjustment is contrary to output.
    That is to say, only PWM input become 0, output is 100% value.
    Best regards.

    rokenbuzz
    October 20, 2017 at 2:38 pm
    Post count: 0
    #23398 Reply |

    It seems I needed to keep ‘key’ floating.  In any case, it’s finally working.

    rokenbuzz
    October 22, 2017 at 10:54 pm
    Post count: 0
    #23515 Reply |

    Actually, ‘key’ acts as enable/disable.
    There should be a manual written for this.

    Mustafa
    November 6, 2017 at 11:24 am
    Post count: 0
    #24417 Reply |

    Hello,

    I have the
    <div class=”a-text-center a-fixed-left-grid-col a-col-left”>
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    <div class=”a-fixed-left-grid-col a-col-right”>
    <div class=”a-row”>DROK Numerical Control Regulator DC 8-60V to 10-120V 15A Boost Converter, </div>
    </div>
    <div></div>
    <div>When I  input 12V or 24V, it works ok until CC is complete but the device doesnt go into CV mode. when I turn off and turn it back on it starts applying constant volts. In other words it doesnt limit the voltage until I reset it.</div>
    <div></div>
    <div>P.S.: when the input voltage is 38V, CV works great.</div>
    <div></div>
    <div>Note: My output is 54V.</div>

    Drok
    Keymaster
    November 7, 2017 at 4:07 am
    Post count: 2971
    #24439 Reply |

    Hello Mustafa,
    Thanks for writing in.
    Would you please let us know if your input power is closed to the output power you want to set?
    When you input 12V，24V and 38V respectively, What is the corresponding input current and output current？
    Best regards.

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