this will work???(suggestions Please)

hai every one,,.....

refer the circuit ,,,,here vcc 1(dc source ) i am generating from ac source

( ex- smps)here i used p channel mosfet as a switch(refer ckt),,, through mosfet

vcc will be generated which will be the input for a battery charger ,,,,,, . my

requirment is like this ,,,,, when ac presents vcc1 will be available then mosfet

should turn on so vcc will be available battery charger should charge the battery

when ac is absent no vcc1, but vcc will br available because battery connected ton

vcc through diodes,,, important is mosfet should go off immediately and it should

isolate vcc and vcc1......, i hope this ckt will work but i have a little doubt about the

turn off of the mosfet,,,,,, give me your suggestions.............

kamal.....

this will work???????????

I may not be understanding your description well.. however, it seems that your charged battery will slowly be discharged through Q2 since it will not turn off, whether Q1 is on or off.

Re: this will work??(suggestions please)

correct,,,,, task is mosfet should turn off sharply when ac is not prsent.

let me explain my requirment,,,

when AC present VCC1 will be prsent (from AC-DC converter which i mention as

DC source.)this VCC1 is the source for the battery charger and DC-DC converter

(which is connected to VCC)whether AC is present or not DC-DC converter should

be ON.,,,,,,,,

when AC-DC ON it will feed power to the dc- dc converter and charger,,,,,

when AC is absent battery should feed the power to the DC-DC converter,,,


here my requirment is when AC is absent i want to isolate AC/DC from battery

(from VCC) I can achieve this with out mosfet it self ,,,,,,, i can use a diode

instead of MOSFET refer circuit 1........ but loss will be more (compare to MOSFET)

since i want to achieve much higher efficiency i want to replace the diode with a

MOSFET ,,,,,, so think in that way ....,,,,, better ideas and suggestions will be really

appreciated

kamal