how to design smooth swithing from CC mode to CV mode for battery charger?

[flesher]

Hi, I am trying to design a Li ion battery charger. after reading some datasheet, I found that the smooth switching from constant current mode to constant voltage is critical point. I found that implementation in LTC4062 is quite interesting. here I have some question about it
1), why the bulk of pass pmos need to connect to the VCC through a diode ?
2), how the CA VA TA loop works? I do not really understand those diode's usage.
3), It looks there are many loop. I guess it is quite difficult to make it stable.
how to select all the opamp bandwidth?

Thanks in advancd

flesher

 

[flesher]

anyone help me?

 

[dick_freebird]

1) PMOS bulk is diode blocked so that the battery doesn't
discharge against a depowered charger.

I doubt that "smooth" switching means a whole lot to the
battery. Decisive is good.

2) The diodes (w/ current sink load) appear to simply be
"winner takes all" analog logic. If CA or VA swing too high
then the output device gets choked off. TA overrides the
current mode setting if overtemperature, otherwise lets
it be, etc.

3) Many loops but only one at a time should be "in charge".
They don't have to be at all aggressively tuned, the battery
is dumb and slow.