question about 'loss of lock' and 'loss of clock'

[bluehacker]

hi everyone

I read MC9S08AC16 datasheet, the chapter about ICG module  says there are two kind of errors called 'loss of lock' and 'loss of clock'.

then, what is the difference between loss of lock and loss of clock?

hope your explanations, thanks 

[bigmac · Accepted solution]

Hello,

The two error states are sensed in different ways.  The loss of clock error is determined by whether the reference clock signal (internal or external) meets some basic timing criteria.  It will mostly be of value when using an external reference.

The loss of lock error is determined by whether the output of the DCO (part of the FLL) instantaneously meets a frequency accuracy requirement, relative to the reference frequency.  Obviously, a loss of clock condition will also result in loss of lock whenever the FLL is used.

A loss of clock detection and reset is of most interest when operating in one of the FLL bypassed modes.

Regards,

Mac