I'm looking at this circuit, Figure 1 for use in a standalone HEI box for
automotive use.
From the circuit, are there any circuit protection devices that should be considered or include with this application schematic. Planning on eliminating
the 350V zener and replacing the single MJ10012 with a higher rated device.
Greater than Vceo 550V per the ** note.
The full data sheet is attached here.
I've identified issue with the MJ10012 and considered using the MJ10014.
However, I've found what I think is a worthwhile candidate to use instead.
The FCPF400N80Z, N-Channel SuperFET II Mosfet. A Fairchild no On Semi.
It's an 800V, 14A and 400m Ohms.
I need to figure out how to incorporate it in the MC3334 design.
Cheers,
automotive use.
From the circuit, are there any circuit protection devices that should be considered or include with this application schematic. Planning on eliminating
the 350V zener and replacing the single MJ10012 with a higher rated device.
Greater than Vceo 550V per the ** note.
The full data sheet is attached here.
I've identified issue with the MJ10012 and considered using the MJ10014.
However, I've found what I think is a worthwhile candidate to use instead.
The FCPF400N80Z, N-Channel SuperFET II Mosfet. A Fairchild no On Semi.
It's an 800V, 14A and 400m Ohms.
I need to figure out how to incorporate it in the MC3334 design.
Cheers,
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I would replace the MJ100012 as I have no trust in them building power supplies for audio amps many of that type failed very easily and I replaced them with Mosfets which are miles more reliable than those BJT,s especially in that type of automotive circuit.
The one you picked has plenty of safety features and is used in high speed switching which would suite your particular application.
Duncan, how would the MJ10014 compare to the MJ10012?
Going back to the FCPF400N80Z - N Channel SuperFET II Mosfet,
how would I set that up for a similar "darlington" type configuration?
Or, would I only use one? Would it have enough gain?
Here are their data sheets. Trying to visualize how the MOSFET
circuit would change to make it function?
cheers,
Going back to the FCPF400N80Z - N Channel SuperFET II Mosfet,
how would I set that up for a similar "darlington" type configuration?
Or, would I only use one? Would it have enough gain?
Here are their data sheets. Trying to visualize how the MOSFET
circuit would change to make it function?
cheers,
The MJ10014 is a higher voltage version of the MJ10012 there is a slight difference in gain but in your use of it that wont matter too much.
A Mosfet is voltage driven not current driven like BJT so the input biasing of the BJT is not used .
I will try and get you a simple circuit showing the changes .
A Mosfet is voltage driven not current driven like BJT so the input biasing of the BJT is not used .
I will try and get you a simple circuit showing the changes .
So, I need to look at voltage driving the MOSFET.
We covered it in my solid state devices class but didn't
spend much time on it. We didn't delve into design at all
as it was a EE Technician Class.
We covered it in my solid state devices class but didn't
spend much time on it. We didn't delve into design at all
as it was a EE Technician Class.
Yes Sync its not hard to learn this plenty of easy explanations and circuit diagrams online not much needed to do to change from a BJT to a mosfet just remove the bias for a start and just watch the input doesn't go high that's why zenners are fitted to the gate to limit this .
On the positive side not so much worries about current surge , I have had class A designs overload during testing and the worse that happened to TO3 designs was the blackening of the metal , plastic versions held up well as well.
On the positive side not so much worries about current surge , I have had class A designs overload during testing and the worse that happened to TO3 designs was the blackening of the metal , plastic versions held up well as well.
duncan2, okay.
As I go through some of the online tutorials, it seems that I'll need a gate driver,
and also some gate resistance. I do have some drivers that I used on another project.
As I go through some of the online tutorials, it seems that I'll need a gate driver,
and also some gate resistance. I do have some drivers that I used on another project.
If the M3334 IC now feeds a FET rather then transistor configured at two transistors in a darlington configuration, how do I configure the MOSFET?
AOE doesn't address this subject.
Is it as simple as 1st FCPF400N80Z FET source to 2nd FCPF400N80Z FET gate then source to ground and tie the two drains together?
Or will just one FCPF400N80Z be enough?
Cheers,
AOE doesn't address this subject.
Is it as simple as 1st FCPF400N80Z FET source to 2nd FCPF400N80Z FET gate then source to ground and tie the two drains together?
Or will just one FCPF400N80Z be enough?
Cheers,
I'll ask one of the mods to change the title to something different.
Changing from BJTs to MOSFETS, do I need a driver FET?
Changing from BJTs to MOSFETS, do I need a driver FET?
No you don't need a FET driver most mosfet output amplifiers use BJT drivers although you can build an all FET power amp.