I guess I could use one trans instead of a FET, although that diagram looks like a FET trans

 

No, it would still require 2 transistors as a high side switch. Can you switch the low side?

 

Yes

 

Good then the low side schematic should work with a logic level N channel mosfet as shown.

 

Good then the low side schematic should work with a logic level N channel mosfet as shown.
View attachment 298137

Thanks, one last thing do I absolutely need that resistor in parallel on the gate and why? because it seems like that resistor would pull the pwm to ground

 

Yes it's required to pull the gate to ground potential otherwise the FET will most likely always be on if the PWM generator is not connected.
The PWM generator has a 50 ohm output impedance so the 10K resistor will not have any effect on its output. Install the 10K resistor regardless if the generator is always connected.

 

What if I was to use an IRF9Z44NPBF, would the configuration be the same as IRLZ?

 

What if I was to use an IRF9Z44NPBF, would the configuration be the same as IRLZ?

The leads of the transistors are marked the same but wouldn't recommend using.
The output from the PWM generator was stated at 10Vpp. That's only 5 volt peak and the reason why I suggest using the logic level mosfet.

 

We are studying ISO transients and are building a load box. This load box has an N channel MOSFET and 47nF capacitor. The input will be 13.5 volts and up to 1.4 amps. The output will be wired to a connector to a harness that will be connected to a circuit board with 40 LEDs and the duty cycle is 65pct. How would I go about wiring the pwm and Vbat? I attached a small schematic. I am thinking about using VN2210 for the FET but maybe I should use something different?

Hi,

I see you had a number of replies already, so I'll just add a little.

I see you have a capacitor on the output of the mosfet. That's usually not a good idea because it will cause the mosfet to have to conduct large spike currents. I'm not sure if that cap is really in the circuit though you can verify that.

There other thing is the generator. Does the output really have a 50 Ohm output impedance? I ask because it is not good to drive a mosfet gate with a device that has too high of an output impedance or that could cause slow rise and fall times which would heat up the mosfet more than needed.
They make dedicated mosfet driver chips for that, but you may not need that.

 

Hi,

I see you had a number of replies already, so I'll just add a little.

I see you have a capacitor on the output of the mosfet. That's usually not a good idea because it will cause the mosfet to have to conduct large spike currents. I'm not sure if that cap is really in the circuit though you can verify that.

There other thing is the generator. Does the output really have a 50 Ohm output impedance? I ask because it is not good to drive a mosfet gate with a device that has too high of an output impedance or that could cause slow rise and fall times which would heat up the mosfet more than needed.
They make dedicated mosfet driver chips for that, but you may not need that.

Hello, it does say on the datasheet for the keysight generator amplitude range 10vpp into 50ohms. Thanks

 

I think the the cap is there for a little hold up capacitance on transient pulses

 

Hi,

What do you mean?

 

ISO7637 voltage drop out and other tests