[SNIP]
> The only way this can realisticly happen is if the measured 8.4 volts in CC mode is not the same as the set 8.4v in CV mode. It wouldn't take much voltage error to cause this.
>
> Is your switching between CC and CV mode done in analog (i.e. current limited voltage source) or by the PIC?
>
> Regards
>
> Mike
>   

Bingo. See reply.

..and yes, the MSP430 does the switching, in conjunction with hardware. 
So there is actually a brief period where the current is turned off, 
then hardware is reconfigured for CV mode, then restart. The MSP430 
controls an analog setpoint voltage which in turn controls the 
regulation hardware.

Mark
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