mosfet IRFZ44n question

hi all

Iam trying to drive on/off load using IRFZ44 N-mosfet...
I have the following

I connect the +12 Vcc directly to the drain and the load between Source & GND..
when aplying +12V to gate i have only about 8.5 v on load
But as soon i increase gate voltage to 15 i get the 12V dc on the load

is there any way to solve this except connecting the load between Vcc and Drain

BR

khgsm2007 said:

hi all

Iam trying to drive on/off load using IRFZ44 N-mosfet...
I have the following

I connect the +12 Vcc directly to the drain and the load between Source & GND..
when aplying +12V to gate i have only about 8.5 v on load
But as soon i increase gate voltage to 15 i get the 12V dc on the load

is there any way to solve this except connecting the load between Vcc and Drain

BR

Click to expand...

What you are describing is the classical High/side & Low/side drive dilemma. The problem you are having is that the load is on the low side, so Vgs, which turns on the mosfet, is offset by the load's voltage. By moving the load to the high side, you won't have that problem, because Vgs is now measured directly to ground.

If you want to use a low side load, why not consider using a P-channel mosfet? Then your load can be connected directly to ground.

Re:

hi

Thanx alot for fast replying..
I'll try to use the -P- mosfet

BR

khgsm2007 said:

hi

Thanx alot for fast replying..
I'll try to use the -P- mosfet

BR

Click to expand...

Don't forget to invert the gate signal, too!

Anyway, what's so difficult connecting the load with the drain, and the second terminal of the load to V+? Connect the source to GND and use a positive going gate voltage for control - That's for an N-Channel MosFet.

Mosfet????? An airsoft gunsmithing told me to put a "mosfet" to my AEG to lessen the arcing on the trigger switch.The AEG uses 8.4v - 12V Depending on Motor voltage capacity.IS IT TRUE.
IF NOT HOW???

RE

hi
Actualy iam trying to get AC square wave over the load using 4 N- type mosfet's,, I know connecting the load Between VCC & drain will make the VCC to drop over the load But this will not help getting AC square wave
I just thougt that no matter where to connect the load as we fire the Gate by avolt larger than Vth .
any way i think it good idea to try with P type

Thanx alot

BR

Re:

hi
I try with P type mosfet and it works perfect

thanx alot for help
BR