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CC3301: calibration phase

HS FAE Germany
Mastermind 32240 points
Part Number: CC3301

Tool/software:

Hi,
how long is the calibration phase. How often must the CC3301 be calibrated during operation?

Regards, Holger

  • 0
    TI__Mastermind 30790 points

    Hi Holger,

    The CC3301 firmware automatically performs calibration every 5 minutes. Is there something more specific you are looking for?

  • 0 in reply to Sabeeh Khan1
    TI__Mastermind 32240 points

    Hi,
    the max VPA is 340mA but customer has only 120mA. So the idea is if we can buffer the energy for the calibration. Do you know how long the calibration procedure will take?

    Regards, Holger

  • 0 in reply to HS FAE Germany
    TI__Mastermind 30790 points

    Hi,

    What do you mean by the 120mA figure? Is this the maximum supply that your customer has available? Can you please clarify this? If so, the customer will need to increase this supply regardless of the calibration current consumption and should follow our datasheet spec. 

    The calibration procedure should take about 20 ms. 

  • 0 in reply to Sabeeh Khan1
    TI__Mastermind 32240 points

    Hi Sabeeh,

    yes, the 120mA is max with the current power supply. They only have to send 20 bytes every minute. So I thought they can harvest energy between TX phases.

    Regards, Holger

  • 0 in reply to HS FAE Germany
    TI__Mastermind 30790 points

    Hi Holger,

    I will need to assign this ticket to the hardware team, but I do not believe this would be a suitable design given the datasheet restrictions. 

  • 0 in reply to Sabeeh Khan1
    TI__Mastermind 45835 points

    Hey Holger,

    Current ratings of regulator is irrelevant to the consumption over time. If an LDO or DCDC is rated for 120 mA max output current then exceeding that can cause negative impact to performance of the regulator -  instability/load regulation issues/thermal issues/over current protection. Now if you are saying you have some way for that to never happen even when our transient current can reach 340 mA on the 3.3V rail then those factors don't apply. I just don't think its that straight forward to implement - however this is a forum for WIFI products so I'm not the biggest expert in Power regulation at TI. An effort like that would require and accurate representation of the current profile over time during their actual application operation - this would help rule out any scenarios where the storage elements don't have enough energy to supplement our device , thus requiring these peak load currents from the regulator. 

    I'm no saying its impossible, but my team won't be able to support an endeavor like this. For you specific question on calibration, the timings have been highlighted:

    Every 5 minutes, expect 340mA of continuous consumption over 10ms - the current is Duty cycled (~50%) over the 20 ms calibration period.

  • 0 in reply to Dylan Hubbard
    TI__Mastermind 32240 points

    Hi Dylan,
    I was expecting that you had a current profile (over time) from typical low data rate application. So I can check be myself if my power supply would work or not.

    Regards, Holger

  • 0 in reply to HS FAE Germany
    Expert 1271 points

    Regardless of the data rate you have to be able to handle the 340mA current load that happens at a 50% duty cycle over a 20ms period every 5 minutes. Can you?

    This sounds like trouble all the way around...

  • 0 in reply to Dean Ramsier
    TI__Mastermind 32240 points

    Hi Dean,

    > 50% duty cycle over a 20ms period
    that means 100% over 10ms period for calculation? Or how should I understand that?

    Regards, Holger

  • 0 in reply to HS FAE Germany
    Expert 1271 points

    I'm not TI, and I haven't investigated this myself. But there is a published minimum requirement and you are far, far below that. In my experience (having been burned by in-sufficient power supply on an evaluation board used with an external WiFI radio module)  you are asking for trouble. It might work most of the time, if you're unlucky. Or not. But if you need reliability at normally accepted levels, you need to design accordingly.

    If you really want to take on the liability of telling your customer their design is sufficient, you will need to exhaustively test this yourself. Make sure to cover all possible scenarios, all possible channels, all possible data rates, worst case throughput, worst case  thermal conditions, and characterize the supply during the testing. Remember, this is WiFi. There are more transmissions than just the data packets sent by the application. Make sure you understand all that too.

    Or just break the news to them that their power supply design isn't sufficient...