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Designing switching step-down for beginners

can altineller
Expert 1470 points
Other Parts Discussed in Thread: LM2596, TPS82130, TPS62136

Hello,

I am trying to design my own switching step down power supply using TI parts. The requirements are Input 6V-15V and output 5V fixed, @2A or close.

Now I am aware of the WeBench tool, as a matter of fact I spend hours reading different datasheets and reviewing different designs, but being a beginner and having no experience in building switching power supplies, I could not determine a part number to start with.

What would be a good starting point for me? I will basically construct the circuit on breadboard for now,  and measure different things to see if it suits my needs.

Basically I need 5V fixed output, (and would be great if i did not need resistors to determine vout) - around 1.5-3A, and enable pin that is active on high. 

I found a LM2596 - which satisfies my basic requirements, with the exception of EN pin being active low. (I need an active HIGH EN pin, because I will use it with hibernate feature of a mcu)

Any help, ideas and pointers in the right direction would be greatly appreciated,

Best regards,

C.

  • 0
    TI__Guru*** 142730 points
    Hi C,

    That device is a big one, which makes it easy to solder by hand.

    A much smaller module and as simple is the TPS82130. If you do need 3A or want to operate at higher ambient temperatures, a TPS62136 will be better.

    With any power supply, we can't use the traditional breadboards that we used in school as these have far too much inductance. Do yourself a favor and order the EVM of the device you want to evaluate. This is a known working circuit on a known god layout.
  • 0 in reply to Chris Glaser
    Expert 1470 points
    Hello Chris,

    I have read the datasheets of both devices, and decided to draw a test circuit, but however I am using eagle.

    The TPS82130 uses a "8-Pin µSiL Package" and I usually draw my own packages in eagle, or get a similar package and modify it, but for this package I have no starting point.

    Is there any resource that I can use to convert or redraw this package?

    Best regards,
    C.
  • 0 in reply to can altineller
    TI__Guru*** 142730 points
    I recommend ordering the EVM, if you just want a board to run some tests on. This should be much cheaper than making your own PCB.

    A footprint for each device is found on the product page here: www.ti.com/.../pinout-quality