TL494 Constant Current and Constant Voltage

Discussion in 'General Electronics Chat' started by circuit1234, Jun 18, 2016.

  1. circuit1234

    Thread Starter New Member

    Jan 7, 2015
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    Hi
    can anyone help me to make work the constant current circuit with TL494 Half bridge config , Constant Voltage is working ,
    in constant current mode even the the ic can control the current the wave form is oscillating in sawtooth shape at 50hz to 100hz in some range like 0.5amps to 0.65
    and 0.8 to 0.9 , other range is ok

    My SMPS is 100Volt and 1Amps CVCC, running at 100khz , attached is the TL494 pic config and the feedback loop compensation , PIN 16 , and 15 is assigned for current sensing , if feedback compensation is the please help me to design the feedback loop
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    You cannot have both constant current and constant voltage unless you have a fixed value load. What are you trying to do exactly?
     
  3. Dodgydave

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    Jun 22, 2012
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  4. circuit1234

    Thread Starter New Member

    Jan 7, 2015
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    I am trying to make Variable power supply of 100V and 1 Amps
    i know its not possible to get CC and CV at the same time , either CV or CC
    In CC mode the wave form is oscillating and i think its about the feedback loop problem , if possible can you help me
     
  5. Alec_t

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    According to the TL494 application notes about the IC output transistors they "are configured as open collector/open emitter, and each is capable of sinking or sourcing up to 200 mA." Also, the notes discuss fold-back current-limiting rather than constant-current control, so this IC may not be optimum if you want true constant current control.
    Your posted circuit is incomplete and doesn't show the necessary current-boosting or high voltage stages or the feedback sources for voltage or current.
     
    Last edited: Jun 21, 2016
  6. dannyf

    Well-Known Member

    Sep 13, 2015
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    Most of those requests for constant voltage or current controls are due to a lack of understanding of what "constant voltage / constant current" means.
     
  7. circuit1234

    Thread Starter New Member

    Jan 7, 2015
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    Hi Alec thanks for the info
    Can you please tell me what is Fold back Current limiting . In many circuits and SMPS module they use TL494 for doing CV and CC
    my high voltage stage that is Vbus is 395 from the PFC circuit . Attached is the circuit for the TL494 and the output , Is there anything i need to do in feedback loop
     
  8. Alec_t

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    Sep 17, 2013
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