Sceadwian:
I'm sorry, I think I don't explained it very well. I mean than I want a swiching on delay, ie, time to change from the OFF state to the ON state (no the global period) of aprox 50 ns with a frequency of 100 KHz. I want also a swiching off dealy, ie, time to change from the ON state to the OFF state of aprox 50 ns. The battery size is aprox half of a car's battery.
Thank you for your answer.
ronv:
The output voltage is 4.25 V. I'm looking a FET driver, in fact. Thanks.
peufeu:
The driver you give me is very good, but it is well suited for a NMOS FET. I aprecciate this driver, and I think I will use it. Thank you for the answer.
In conclusion:
I've been looking a lot, and I think that is better to change the PMOS for an NMOS. I though that it would be better to use a PMOS for a simpler driver circuit, but in practice I realized that there's a lot of drivers for NMOS swichs and I have more options. I also have more cheaper swichs with NMOS and it is not so dificult to change the swich.
Thank you everbody.
I give the problem solved.