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TMS320F280037C: Possible configuration for 3.3V analog & digital power supply

Ella KIM
Expert 3802 points
Part Number: TMS320F280037C
Other Parts Discussed in Thread: TIDA-01281, SN6505B,

Hi Team,

 

I’m wondering – what is the most common way to supply analog 3.3V and digital 3.3V? I see https://www.ti.com/tool/TIDA-00951 and Common Documentation (TIDA-01281) adopts one SN6505B and two LDOs for each. Is it the most common way? Customer is currently using only one DCDC to share two 3.3V rails and considering to switch their design.

 

>> Common Documentation (TIDA-01281)

 

Customer is thinking to use 2ch buck solution but I know that our buck portfolio doesn’t have two rails isolation device - Buck converters (integrated switch) product selection | TI.com. If there’re other configurations, can you list them up so that they can review?

 

Thanks,

Ella

  • 0
    TI__Intellectual 2986 points

    Hi Ella, 

    The SN6505B circuit in TIDA-00951 is to generate isolated power for CAN transceiver, not for MCU. I suggest to follow MCU power guidance to design the power rail. Normally LDO is required after DCDC for lower noise and ripple, but isolation is not necessary. but again, need to follow the guidance of MCU. 

    Best Regards,

    Ryan Tan

  • 0 in reply to Ryan Tan
    TI__Expert 3802 points

    Hi Ryan,

    Where is the guidance regarding this matter? I cannot find it in datasheet. Sharing a reference design that adopts the most common and desirable power design would help!

    LDO can be in reference to AGND. Otherwise it can be in reference to DGND. Currently my customer is using a DCDC (competitor's) and putting ferrite bead to separate DVCC_3.3V and AVCC_3.3V. Is it a desirable way? 

    Sincerely,

    Ella

  • 0 in reply to Ella KIM
    TI__Intellectual 2986 points

    Hi Ella, 

    If you look at TMS320F280037C datasheet, you will find the recommended working conditions: 

    So basically you just need to make sure all voltages are within the recommended range at all conditions. 

    With further details on the power recommendations, I suggest you to raise another post specify for C2000 power recommendations. 

    Ryan Tan 

  • 0 in reply to Ryan Tan
    TI__Expert 3802 points

    Hi Ryan,

    I don't think my question get across to you. My question is "how to separate digital 3.3V and analog 3.3V when a DCDC or LDO generates single 3.3V."

    TPS5429x 1.5-A and 2.5-A Dual, Fully-Synchronous Buck Converter With Integrated MOSFET datasheet (Rev. A) (ti.com) 

    Pleaes let me know if you expect possible issue with TPS5492x to generate two 3.3V supplies for MCU.

    Ella

  • 0 in reply to Ella KIM
    TI__Intellectual 2986 points

    Hi Ella, 

    Typically a system requires cleaner analog power than digital power, but still depending on the specific systems (for examples if you are using analog power for ADC, clean power is necessary). 

    Bead is one option to separate analog and digital power or LDO is also good one. I don't know exactly if any potential issues with TPS5429x. You need to check with PL. 

    Ryan Tan