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Circuit recommendation for AC/DC converter

Prakash Ramamoorthy20
Prodigy 155 points

Hi

   I'm trying to build an energy meter. I choose the MSP430f677x series as a micro controller for this purpose. In order to power up the MCU I need an AC-DC converter which can convert 180-250V AC into 5V DC. Right now I'm thinking of having a bridge rectifier followed by a linear regulator.

Can someone suggest me a efficient way to this. Can you suggest some parts as well.

  • 0
    TI__Mastermind 27145 points
    Hi Prakash,

    Thanks for your interest in TI. A linear regulator would be quite inefficient because of the large difference between input voltage and output voltage (efficiency would be less than 3% at 180Vac and even less at 250Vac). I would suggest a low power flyback design for this use case. I am not sure how much load current you are expecting the micro to consume but I think PMP40381 is a good place to start. PMP40381 is a power reference design for E meter that supplies a few different 5V rails depending on the necessary load current and accepts 85Vac to 300Vac input.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Prodigy 155 points

    Hi Ben,

          Thanks for the quick reply. I will follow the design that you suggested. I would like to know the possibility of not using transformer in circuit. I understand that transformer can give me voltage step down as well as isolation but I want to keep the form factor small. Is there any other combination of IC that can replace transformer? and would it be wise to do it?

  • 0 in reply to Prakash Ramamoorthy20
    TI__Mastermind 27145 points
    Hi Prakash,

    Power converters with line voltage input are typically isolated, in part, because of safety concerns and the danger of high voltage. I would caution against using a non-isolated topology for this use case. If size is a key concern, a quasi-resonant flyback could be a good choice here. Take a look at this reference design:www.ti.com/.../PMP40228.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Prodigy 155 points

    Hi Ben,

    Thanks for your input. I will look into more details on what you suggested.