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LMR61428: Seeking assistance in picking the right part

James Wood
Prodigy 50 points
Part Number: LMR61428

I'm an old-school developer with mostly linear-regulator experience and am looking for tips on picking the right 'boost' switching regulator for a specific project. It needs to take +5V in, either from a wall-wart or a battery, and give +10V out at 150-200ma. The device it's powering does low-level RF signal analysis in the 500kHz to 2MHz range, so I figured the switcher ought to run somewhere north of 2MHz.  I initially tried a somewhat slower boost switcher with a built-in spread-spectrum 'noise abatement' feature that turned out to create a good deal of hash. This will be a low-production item utilizing a lot of discrete components, so a chip that can be hand-soldered would be appreciated.  The LMR61428 is nice in this regard, but I wonder if its operating frequency can be pushed a bit higher in light of the limited current it needs to supply.  Many thanks in advance for all words of wisdom.

  • 0
    TI__Mastermind 34201 points

    Hello James,

    Thank you for reaching out.

    So you need a boost converter that switching frequency higher than 2MHz, right? May I know the reason?

  • 0 in reply to Zack Liu
    Prodigy 50 points

    Hello, Zack, and thanks for the interest.  The device to be powered is a quite sensitive radio receiver in the 500kHz-2MHz portion of the spectrum.  Attempts to use switching supplies at a frequency within this range, or with harmonics in this range, have generated spurs that interfere with reception.  Thus I assumed that a higher supply operating frequency might be the answer.  I am open to suggestions, and thanks!

  • 0 in reply to James Wood
    TI__Mastermind 34201 points

    Hello James,

    Did you already set LMR61428 switching frequency to its maximum 2MHz?

    You can take a look at TPS611781 or TPS61378. These two devices switching frequency could be set to 2.2MHz typically maximum.

  • 0 in reply to Zack Liu
    Prodigy 50 points

    I've ordered the LMR part, which should arrive soon, and will try it first at its highest switching frequency. The other parts are both QFN packages, which would prove a bit more difficult for hand assembly in small production runs; the end product is mostly thru-hole with only one other SMD part.  I did fine one other boost converter in the VSSOP format that ran at 2.2MHz, I'll look that one up.  Many thanks for your tips!

  • 0 in reply to James Wood
    TI__Mastermind 34201 points

    Hi James,

    Let us know if you have further questions.