How to find N and P type equivalent MOSFETs?

Thread Starter

electronice123

Joined Oct 10, 2008
311
Hello everyone,

I am working on a H-Bridge circuit which uses logic level MOSFETs. I already have the N channel FETs picked out: NTE2981
- drain to source breakdown voltage 100
-Gate to source cutoff voltage 2.0
-Max continuous drain current 7.7 Amps
-Total power dissipation 42 watts
-Rds .27 Max

I am trying to find the P channel equivalent of this MOSFET but have had no luck. Anyone know of any charts where I could find the equivalent P channel logic level MOSFET? I would greatly appreciate it!
 

Ron H

Joined Apr 14, 2005
7,012
I'm curious about how you plan to use logic level p-channels. What is the supply voltage of your H-bridge?
 

Thread Starter

electronice123

Joined Oct 10, 2008
311
The H-Bridge uses about 60V but I am going to use a function generator which outputs 5V for switching the FETs.


I must clarify that the circuit is not for a motor controller. I want to switch the polarity across 2 small coils (electromagnets) to make a vibrating tool. The operating frequency will probably be about 50kHz or more.
 
Last edited:

Ron H

Joined Apr 14, 2005
7,012
The H-Bridge uses about 60V but I am going to use a function generator which outputs 5V for switching the FETs.


I must clarify that the circuit is not for a motor controller. I want to switch the polarity across 2 small coils (electromagnets) to make a vibrating tool. The operating frequency will probably be about 50kHz or more.
How do you plan to drive the p-channel device? The source must connect to +60V. The gate voltage must be at 60V when the transistor is off, and 50 to 55V when the device is on.
 

Thread Starter

electronice123

Joined Oct 10, 2008
311
Hmmm. Perhaps I am missing something here?

I have several coil drivers which use logic level mosfets (5V at gate) and they switch over 10V at the coil.
I don't see how the H-Bridge would be different.....
 
Last edited:

Ron H

Joined Apr 14, 2005
7,012
Hmmm. Perhaps I am missing something here?

I have several coil drivers which use logic level mosfets (5V at gate) and they switch over 10V at the coil.
I don't see how the H-Bridge would be different.....
Logic level N-channels are fine for the pulldowns. With a 60V supply, any pullup transistors you use (n- or p- channel, npn, pnp) will require some sort of level translator.
Post a schematic of your H-bridge.
 

Thread Starter

electronice123

Joined Oct 10, 2008
311
I have not built an H-Bridge circuit before.... I am not familiar with a level translator?

I planned on using a function generator along with a schmit trigger to invert the one signal. Then I would add in a circuit to add dead time between switching.

I thought I could take the 5V signal directly from the schmitt trigger (40106 or 7414) outputs to operate one side of the bridge and use the non-inverted signal to operate the other side.
 
Last edited:

Ron H

Joined Apr 14, 2005
7,012
I have not built an H-Bridge circuit before.... I am not familiar with a level translator?

I planned on using a function generator along with a schmit trigger to invert the one signal. Then I would add in a circuit to add dead time between switching.

I thought I could take the 5V signal directly from the schmitt trigger (40106 or 7414) outputs to operate one side of the bridge and use the non-inverted signal to operate the other side.
You really need to read about H-bridges before you try to build one. They are not as simple as you think.
 
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