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Reference design with Cockcroft–Walton circuit

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Replies: 6

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Dear all,

I would like to ask a question.

I am looking for a reference design with a Cockcroft–Walton circuit.

I am trying to generate voltage from our customers under the following conditions

Input voltage: DC24V (DC20-30V)
Output voltage: DC6.6kV and -4.0kV
Output current: total 1 ~ 1.2mA

I believe that using the Cockcroft–Walton circuit can meet this requirement.

Therefore, we are looking for a reference design that satisfies this condition.

Is there a reference design with Cockcroft–Walton circuit under the above conditions?

Best Regards,

Y.Ottey

  • Ottey

    I am assuming that you are referring to the following Cockcroft–Walton circuit that this article explains https://en.wikipedia.org/wiki/Cockcroft%E2%80%93Walton_generator

    This circuit only uses passive components of capacitor and diodes.  TI does not make either one of these devices.  As a result such a design would not demonstrate performance of any TI IC, so we do not have a reference design of such a circuit.

    That being said, in order for such a circuit to work you need an AC input, not a DC input.  Based on the specification you list above you will need a DC/AC inverter to generate an AC signal that will be the input to the Cockcroft–Walton circuit.  TI has solutions for this stage. I recommend considering an LM555 555 timer to generate a varying PWM signal, which you can drive a full or half bridge convert with a gate driver like LM5108.

    Best Regards,

    Eric

  • In reply to Eric Faraci:

    Dear Eric

    Thank you for your reply.

    I understand that Cockcroft–Walton circuit  needs AC input.

    I would like to ask more questions.

    1.For example, is it possible to output DC 6.6 kV and -4.0 kV in a cockcroft circuit by curing 24 VDC to AC by increasing the combination of capacitors and diodes to a considerable number?

    2.Our customers want to generate DC output from DC input without converting to AC if possible.

    Is there any other method that satisfies the following conditions? Are there any reference designs that meet this requirement?

    Input voltage: DC24V (DC20-30V)
    Output voltage: DC6.6kV and -4.0kV
    Output current: total 1 ~ 1.2mA

    Regards,

    Y.Ottey

  • In reply to Y.Ottey:

    Dear Eric

    There is an additional question to ask in the first question of the previous post.
    Looking for reference designs, there were the following reference designs.

    http://www.ti.com/tool/PMP8956

    In this, a capacitor and a diode are used to boost the voltage, but I think that adding the capacitor and diode to this will satisfy the conditions I mentioned.

    (Because the output voltage is 120V, I think that it is possible to add 400 times by adding capacitors and diodes.)

    Regards,

    Y.Ottey

  • In reply to Y.Ottey:

    Ottey

    I believe generating a positive 6.6kV is possible, but not possible to generate a negative -4.0kV using a Cockcroft–Walton circuit.  Based on your requirements I believe using a stun gun circuit may be a better fit since it uses a DC input and the transformer allows you to generate a positive or negative voltage (depending on how you reference the transformer outputs).  You can find more information about how to design one here https://www.electronicshub.org/stun-gun-circuit/.

    You are correct about PMP8956.  LM3481 works to invert the AC to DC, which is then passed thru the circuit you highlighted to step up the voltage and filter it back to DC.  The challenge with this design is that it's non-isolated, so it will not be able to generate the negative -4.0kV voltage you require.

    Best Regards,

    Eric

  • In reply to Eric Faraci:

    Dear Eric

    Thank you for your reply.

    I understand that adding 6.6kV to PMP8956 can add 6.6kV.

    Also, regarding the output voltage of -4.4kV, our customer says that if there is a circuit (reference design) recommended by TI,they would like to consider it with TI products.

    I would like a design that TI recommends, but could you make a reference circuit like the one on the link page you wrote (the following circuit)?

    Best Regards,

    Y.Ottey

  • In reply to Y.Ottey:

    Ottey

    We do not have such a reference design at this time.  Please reach out to your local TI representative if you would like help creating a design. 

    On E2E we are happy to answer questions to help with your own design, but you need to reach out to your local TI representative if you need additional support.

    Best Regards,

    Eric