How to design a circuit that protect 7 lithium-ions in series

Is that the only protection you need, overvoltage on charging?

No,I want overcharge and overdischarge protection. My circuit is ok for over- discharge control,but has some problem with overcharge control. When the battery voltage go up slowly, it can give the right protection,but when the voltage go up very fast, it can not catch it.

I'm pretty sure that is what the OP meant. He or she just chose the wrong verb (should have been "require," not "give."). But I did have to read the post twice before I came to that conclusion.

Yeah. That shut me up, too. ;-)

--Mac

I don't see that any of the monolithic protection products handle anything near 10A, so you will have to go custom anyway. The architecture of these IC's is straightforward, the only tricky part is handling sleep mode and other considerations to minimize battery current drain overhead.

Also though, you can do a _lot_ better than 90% efficiency. With reasonable design, you can easily push past 95%, and on larger switchers, figures over 98% become possible. The idea that 90% is a 'best' figure, at these sorts of currents, needs to be definately put to rest...

Best Wishes