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LMR16006YQ5DDCRQ1 and atmega

user6225448
Prodigy 30 points

Hi there!

I am using a LMR16006YQ5DDCRQ1 incl. the circuit in the data sheet for supplying my pcb's with atmega328 or atmega2560.
The problem is: The pcb's can be used normally but when programming the atmega processors I need to use an external power supply for 5V because it does not work with the LMR16006YQ5DDCRQ1.

I don't really know why...
The LMR16006YQ5DDCRQ1 is designed for 0.6A and I am using less than 0.133A at 5V (no peak current) while programming (measuring from labory supply). I also tried to connect the GND but it din't change anything.

Does anybody know why?

  • 0
    TI__Guru 72965 points

    Can you show us your schematic for the power supply and the procedure you are using to test.

    Also, can you take some measurements during good and bad behavior.

    Have you tested with a TI EVM?

  • 0 in reply to Frank De Stasi
    Prodigy 30 points

    Hi!

    We use the schematic from the data sheet: http://www.ti.com/lit/ds/symlink/lmr16006y-q1.pdf (See: Typical Application - Figure 7)

    I supplied the circuit with a laboratory power supply (24V as input) and attached a multimeter for accurate current measurement, which gives me the max value. And then we tried to upload a programme and also run a programme. The upload did not go well... but when supplying with 5V directly I had the same power consumption in total but it worked. So the problem is the LMR16006YQ5DDCRQ1 with its circuit...

    And we have not tested TI EVM... but it should also work well on our own boards, am I right?

  • 0 in reply to user6225448
    TI__Guru 72965 points

    I would test a TI EVM with your load and see it it is OK.  If it is OK, then the issue would be in your PCB layout.

  • 0 in reply to Frank De Stasi
    Prodigy 30 points

    Hi!

    Thanks for your answer.

    We've already tried to populate our pcb with nothing but the processor and the TI component and it does not work. It will therefore also not work with the board, because our PCBs come from a factory with quality assurance and we never have problems with them. It's just that it does not work during the programming process. Therefore, I believe that the circuit with the processor cannot be used at higher frequencies (when programming).

    It would be interesting if there is an alternative to the LMR16006YQ5DDCRQ1 that works without external capacitors and coils (without an external resonant circuit).
    For example: The same PCB works perfectly with  a TRACO POWER - but they are too big for the circuit.

  • 0 in reply to user6225448
    TI__Expert 8245 points

    Hi,

    It should be OK with the schematic on datasheet. There should be some problems on the inductor's saturation current or layout, please check these. Thanks.