I don't understand how something with less resistance conducts better than something that has a higher resistance.
To Me : Duh.. it has more resistance, so it doesn't conduct as well.
Copper Wire
AWG : 12
Length : 2106 Inches
Voltage : 12vdc
Resistance : 28.8 Ohm's
It heats up, and dissipates 5 watts of power, and 0.416A of current passes threw it, to the ground.
Copper Wire
AWG : 12
Length : 210.6 Inches
Voltage : 12vdc
Resistance : 2.88 Ohm's
It heats up, and dissipates 50 watts of power, and 4.16 Amps of current passes threw it, to the ground.
Great. So wouldn't an n-Channel Mosfet with an Rds(on) of 1.2mOhm's heat up quicker, than let's say one that was rated at 5 Ohm's?
The loads current & voltage goes from the Drain to the Source. The Mosfet get's turned on if their is a positive voltage on the gate, and it's greater than the Vgs(th). Got it.
All Ground connections are connected to the Source. The Drain is connected to the negative of the load. Understood.
A 15,000Ω resistor on the gate and source, as a pulldown resistor with a positive 5 volts on the gate. The gate draws 0.000333 Amps (0.33uA), and dissipates 0.0016 Watts (1.6mW) of power. I tested, and understand it.
Why is an n-Channel MOSFET with a (R) Resistance of the (ds) Drain & Source, when the MOSFET is in (on) complete saturation mode, better to have a lower Rds(on) value, than one that has a higher Rds(on) resistance?
It shouldn't heat up or anything if it's higher. According to Ohm's law.
Here's some MOSFETs I pulled from Mouser Electronics.
2.5 Vgs(th), 3.6mOhm's Rds(on)
Mouser Electronics Part # : 78-SUP85N03-3M6P-GE3
2.5Vgs(th), 2.5MOhm's
Mouser Electronics Part # : 595-CSD19536KCS
So what's the difference? Is it a matter of how well one conducts better or worse than the other?
Thanks so much, this has been bothering me for quite some time. I've tried for a couple hours to read and watch videos about it, and I just don't understand. Could someone please help?
To Me : Duh.. it has more resistance, so it doesn't conduct as well.
Copper Wire
AWG : 12
Length : 2106 Inches
Voltage : 12vdc
Resistance : 28.8 Ohm's
It heats up, and dissipates 5 watts of power, and 0.416A of current passes threw it, to the ground.
Copper Wire
AWG : 12
Length : 210.6 Inches
Voltage : 12vdc
Resistance : 2.88 Ohm's
It heats up, and dissipates 50 watts of power, and 4.16 Amps of current passes threw it, to the ground.
Great. So wouldn't an n-Channel Mosfet with an Rds(on) of 1.2mOhm's heat up quicker, than let's say one that was rated at 5 Ohm's?
The loads current & voltage goes from the Drain to the Source. The Mosfet get's turned on if their is a positive voltage on the gate, and it's greater than the Vgs(th). Got it.
All Ground connections are connected to the Source. The Drain is connected to the negative of the load. Understood.
A 15,000Ω resistor on the gate and source, as a pulldown resistor with a positive 5 volts on the gate. The gate draws 0.000333 Amps (0.33uA), and dissipates 0.0016 Watts (1.6mW) of power. I tested, and understand it.
Why is an n-Channel MOSFET with a (R) Resistance of the (ds) Drain & Source, when the MOSFET is in (on) complete saturation mode, better to have a lower Rds(on) value, than one that has a higher Rds(on) resistance?
It shouldn't heat up or anything if it's higher. According to Ohm's law.
Here's some MOSFETs I pulled from Mouser Electronics.
2.5 Vgs(th), 3.6mOhm's Rds(on)
Mouser Electronics Part # : 78-SUP85N03-3M6P-GE3
2.5Vgs(th), 2.5MOhm's
Mouser Electronics Part # : 595-CSD19536KCS
So what's the difference? Is it a matter of how well one conducts better or worse than the other?
Thanks so much, this has been bothering me for quite some time. I've tried for a couple hours to read and watch videos about it, and I just don't understand. Could someone please help?
Last edited: