Thread Starter

Arduinoob

Joined Jul 19, 2021
2
I am making a boost converter following this Tutorial but I don't have the exact MOSFET. I have 2 motherboards laying around and they have some MOSFETs on them some of the names are: P3055, K3918,6670AL(datasheet inserted). There are high switching speeds but the datasheets don't have the max Freq. I am using an Arduino nano btw. Please give me advice on which one I should use. I also have MOSFETs from an old RC car's h-bridge but was not able to find a datasheet
 

DickCappels

Joined Aug 21, 2008
8,000
Tell us more about your circuit. What will the input and output voltages and current ratings be?

Is this going on be a non-isolated power supply? That would be one that uses a choke for the inductor instead of a transformer.

Do you have something like 9, 10, 12, or 15 volts on hand -you might need more than 5V to turn your MOSFET on adequately.

I'm helping a young man in Uzbekistan learn switching power supplies and where he lives he can't just order from Digikey of Mouser so he salvages parts from dead electronics. Last week he fired up his first flyback power supply and it did not take him long to get it working. You can use salvaged parts but you need to consult the datasheet (as I see you have) and even then it might not be the optimal part for your project, but if you are just getting trying out ideas, you don't need the optimum part.
 

sagor

Joined Mar 10, 2019
512
The video tutorial uses a low voltage (55V), low RDSon (0.022 ohm) MOSFET. Also, the gate is "logic level", meaning at 4 to 5V on the gate, it is fully conducting.
So, you can use any similar MOSFET if and only if:
1) It has a Vds of 55V or more, or whatever your design has for voltage.
2) It has a Logic Level gate input (designed for 5V on gate)
3) The RDSon is in the range of 0.022 ohms. Probably anything with less than 0.05 ohm RDSon would do.

Look at whatever MOSFETs you have and compare the specifications. Those are the 3 main options, you must meet all 3.
 

Thread Starter

Arduinoob

Joined Jul 19, 2021
2
Tell us more about your circuit. What will the input and output voltages and current ratings be?

Is this going on be a non-isolated power supply? That would be one that uses a choke for the inductor instead of a transformer.

Do you have something like 9, 10, 12, or 15 volts on hand -you might need more than 5V to turn your MOSFET on adequately.

I'm helping a young man in Uzbekistan learn switching power supplies and where he lives he can't just order from Digikey of Mouser so he salvages parts from dead electronics. Last week he fired up his first flyback power supply and it did not take him long to get it working. You can use salvaged parts but you need to consult the datasheet (as I see you have) and even then it might not be the optimal part for your project, but if you are just getting trying out ideas, you don't need the optimum part.
I think I will
The video tutorial uses a low voltage (55V), low RDSon (0.022 ohm) MOSFET. Also, the gate is "logic level", meaning at 4 to 5V on the gate, it is fully conducting.
So, you can use any similar MOSFET if and only if:
1) It has a Vds of 55V or more, or whatever your design has for voltage.
2) It has a Logic Level gate input (designed for 5V on gate)
3) The RDSon is in the range of 0.022 ohms. Probably anything with less than 0.05 ohm RDSon would do.

Look at whatever MOSFETs you have and compare the specifications. Those are the 3 main options, you must meet all 3.
I think I will use the 6670AL because the datasheet says "this N-Channel logic MOSFET has been specifically designed for DC to DC converters, a MOSFET that is easy and safer to drive(even at very high frequencies), and DC/DC power supply designs" AND has lower RDSon about 0.0085Ω . Though it's max voltage is 30v, it is fine for me.
 
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