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LM34936: is it suitable for a low noise application?

David Corsello
Prodigy 30 points
Part Number: LM34936

I'm a non-engineer venturing into engineering territory.  I'm looking for a buck boost converter that will accept Input power at 11-21V and up to 5A, and put out 13.5V at as close to 5A as possible. Observed current draw at the load is 2.5-3A.. The load device is highly RF-sensitive in the range of 3-30MHz and it produces audio output.  The power source is a solar charge controller that is virtually radio silent, supplied by battery and PV.  I used WEBENCH to locate the LM34936.  It has the right power specs, but I don't know if it and its recommended layout are suitable for a low noise application.  If not, can someone recommend a different chip that would be suitable?

  • 0
    TI__Mastermind 46905 points
    Hi David,

    the engineer supporting this device is out of office. the post is assigned to him.
  • 0 in reply to Jasper Li
    Prodigy 30 points

    Is someone able to help me with this?

  • 0 in reply to David Corsello
    TI__Mastermind 21720 points
    Hi David,

    What EMI specification are you trying to meet? The LM34936 can achieve good EMI performance but it is more related to layout than the device since it is a controller. With proper layout it is probable that the EMI requirement can be achieved.

    -Garrett
  • 0 in reply to Garrett Roecker
    Prodigy 30 points

    Garrett,

    Thanks for your reply.  It's good to know that good layout will produce good EMI performance with this chip.  Not being an engineer, I have no sense of which compliance level would be sufficient.  I learned that CISPR 25 Class 5 is difficult to pass.  If meeting that standard would equate to sufficiently low noise to power an HF transceiver with no audible noise from 3-30MHz, then that's what I'd be shooting for.

    Can I count on WEBENCH to produce a layout that's optimal for my application, or will the layout likely require tweaking?

    If lower noise is possible with a module than with a controller, could you recommend a module that has similar power specs that would be better suited to my application out of the box?  (Maybe 3-5A is not achievable with a module?)

    Dave

  • 0 in reply to David Corsello
    TI__Guru* 78060 points
    Hi David,

    Thank you for your interests. The Webench tool offers a very decent start point for any practical application, but most probably you may need to tweak the design to pass the EMI, because EMI is a system level issue. Follow the datasheet layout guidelines will help you .

    I would recommend you to contact the TI sales/FAE in your region and ask them to leverage TI reference design group to help you to get a design tailored for your specific application.

    Best Regards,
    Youhao