[MKL16Z64VLH4] transit time from FEI mode to FBE mode

[koichisakagami]

Dear community,

We have been considering to use Kinetis KL16 with their product.
Now we would like to estimate the system boot up time .

[Background]
In the data sheet KL16P64M48SF5 Rev 5 : Table 18 MCG spec , tFLL_acquire is 1ms ( Max).

Note 8 : This specification applies to any time the FLL reference source or reference divider is changed,
              trim value is changed,DMX32 bit is changed, DRS bits are changed,
              or changing from FLL disabled (BLPE, BLPI) to FLL enabled (FEI, FEE,FBE, FBI).
               If a crystal/resonator is being used as the reference, this specification assumes it is already running.

[Question]
How long does it take time to change a state form FEI mode to FBI mode ?

Is it 1ms (Max) or immediate ?

Best Regards,
Koichi Sakagami

[mjbcswitzerland · Accepted solution]

Hi Koichi

See the following for practical information about the MCG: µTasker MCG Configuration Support

Since the change from FEI to FBI involves a switch MCG_C1[CLKS] and not the FLL changing its frequenc it should be approximately instantaneous.

To be sure, you can measure it by changing the MCG_C1 register and polling the MCG_S content until it reflects that the change has been completed. There may be different clock domains that are involved which require a small wait before the status updates but it should be very short, but possibly depend on whether switching to the 32 kHz IRC or the 4MHz IRC.

Regards

Mark

Kinetis: µTasker Kinetis support

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[koichisakagami]

Dear Mark-san,

Thank you for your informations.

We understood it well.

Best regards,

Koichi Sakagami