pchannel mosfet as switching application:

[kesavparu]

hai to everyone,
i have one problem, anybody can solve it.

i am using p channel Mosfet(NX2301p) as controling power.


i am given 4.5 dc volatge to source and i am controlling gate with 3v logic control signal, but at drain continusly 4.5dc passes to drain. it is not controlled. i will not use external transistor to control the gate.

any body can fix this problem.

thanking

p.kesav

 

[mister_rf]

That’s a normal situation as long applying Vg =3V and keep the Vs = 4.5V the resulting Vgs=1.5V, so the MOSFET transistor is still on (Vgs>0.7V). The usual way is using an additional transistor, otherwise need to use some resistors in order to lower the Vgs voltage under a safety value, let’s consider this value 0.5V.
Use a 10k gate to source resistor and a 18k series resistor gate to the controlling power signal.

 

[mister_rf]

**broken link removed**

 

[kesavparu]

**broken link removed**

View attachment 72448

thank u for valuable information. but i think 4.5vdc biasing voltage go to microcontroller pin. is it any problem. now i am going choose AO3409, which has VGs=2.4v, i think it will solve my problem

---------- Post added at 07:34 ---------- Previous post was at 07:32 ----------

thank you for valuable information, but i suspect that biasing voltage 4.5dc, can affect 3v microcontroller pin. now i am going to choose AO3409, it has vgs=2.4v, is it solve my problem.
thanking you
kesav