MSPM0C1104: MSPM0C1104 supports for FCL?

Hi Christina,

The MSPM0C1104 does support the Frequency Correction Loop (FCL).

Here is the accuracy of SYSOSC from the device datasheet:

Can you share more detail to what exactly they are executing and the accuracy with and without FCL enabled?

What is the expected result?

How are the IO pulses being generated?

Best,

Owen

Hi Owen, 

Thanks for the feedback. 

Below are details of customer test method:

1. Generating 500 Hz pulses, 50% DC using PA2 pin (1ms High, 1ms Low)
2. Capture signals over period of 5 minutes w/wo FCL enabled using oscilloscope 500 MS/s

With FCL enabled, the pulse measured is 501.313 Hz

Error = 501.313 – 500 = +1.313 Hz (0.262%) 

Without FCL enabled, the pulse measured is 501.319 Hz
Error = 501.319 – 500 = +1.319 Hz (0.264%)

Therefore,

For 5 minutes run, with FCL enabled

Error reduction: 1.319 - 1.313 = 0.006 Hz

Timing error improvement: (0.006 / 1.319​) x 100 = 0.45%

This is surely a timing improvement, but it’s too marginal.

Question:

1. Should customer expect better results with FCL enabled?
2. Does their test method makes sense?

Thanks,

Christina 

Hi Christina,

The rough 0.26% error is pretty good. According to the device datasheet, it is well within the expected error with the FCL enabled at room temperature: +/-1.2%. Since it doesn't seem like a lot of error is being observed when the FCL is disabled, it may seem like they are not receiving much benefit from the FCL, but enabling the FCL will ensure that the error remains within what is listed in the device datasheet.

The test seems reasonable to me.

A possibility to improve this would be to enable the FCC and use a much more accurate reference clock, but in general I think the accuracy they observed is pretty good.

Best,

Owen