# How to find N and P type equivalent MOSFETs?

#### 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
7,014
I'm curious about how you plan to use logic level p-channels. What is the supply voltage of your H-bridge?

#### 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.

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#### Ron H

Joined Apr 14, 2005
7,014
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.

#### 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.....

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#### Ron H

Joined Apr 14, 2005
7,014
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.

#### 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.

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#### Ron H

Joined Apr 14, 2005
7,014
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.