Δυσκολα θα μαθει ,προσπαθει πολυ η Diana αλλα ειναι τα ηλεκτρονικα περιπλοκα , μπραβο για την υπομονη σου . Μας μαθαινεις πολλα , να εισαι παντα καλα !
7:15 at 6v gate voltage it is only 8A . At higher Vgs current capabilities are better because lower internal resistance of the mosfet and less power being dropped across mosfet transistor. Limit is i assume TO-220 package size and it's thermal resistance to case . It cannot dissipate more heat due to it's small contact area with heatsink.
there is a reason to have higher Vgs than Gate Threshold max . I learned this with adjustable load tester that uses mosfet as a load (by dissipating heat) . mosfets have something called ohmic region where they have variable resistance Rds depending on Vgs (above Vth it is what is advertised in datasheet ). That Gate Threshold value on datasheet is where they start conducting yes,, but min typ and max is variation between the same mosfet model (manufacturer tolerance).
"... but min typ and max is variation between the same mosfet model (manufacturer tolerance)." Exactly! That spec is about unit to unit variation in threshold voltage for that particular type. None will have D-S current of at least 100 µA with Vgs below 3 volts. All will have at least that much D-S current flow if the gate-source voltage is at least 4.5 volts (all with the test conditions like Vds and temperature as specified). His statement about "zero ohms" at 4.5 volts is nonsense. The drain-source current with gate-source voltage above the threshold for any individual part depends on the transconductance up to the point where "saturation" occurs and no additional gate-source voltage will cause increase in drain-source current.
Δυσκολα θα μαθει ,προσπαθει πολυ η Diana αλλα ειναι τα ηλεκτρονικα περιπλοκα , μπραβο για την υπομονη σου . Μας μαθαινεις πολλα , να εισαι παντα καλα !
Foarte bine explicat. Mulțumim!
Great video for learn!
7:15 at 6v gate voltage it is only 8A . At higher Vgs current capabilities are better because lower internal resistance of the mosfet and less power being dropped across mosfet transistor. Limit is i assume TO-220 package size and it's thermal resistance to case . It cannot dissipate more heat due to it's small contact area with heatsink.
there is a reason to have higher Vgs than Gate Threshold max . I learned this with adjustable load tester that uses mosfet as a load (by dissipating heat) . mosfets have something called ohmic region where they have variable resistance Rds depending on Vgs (above Vth it is what is advertised in datasheet ). That Gate Threshold value on datasheet is where they start conducting yes,, but min typ and max is variation between the same mosfet model (manufacturer tolerance).
"... but min typ and max is variation between the same mosfet model (manufacturer tolerance)."
Exactly! That spec is about unit to unit variation in threshold voltage for that particular type. None will have D-S current of at least 100 µA with Vgs below 3 volts. All will have at least that much D-S current flow if the gate-source voltage is at least 4.5 volts (all with the test conditions like Vds and temperature as specified). His statement about "zero ohms" at 4.5 volts is nonsense.
The drain-source current with gate-source voltage above the threshold for any individual part depends on the transconductance up to the point where "saturation" occurs and no additional gate-source voltage will cause increase in drain-source current.
might it be that as mosfets get hotter internal resistance in on state is rising so the power dissipation is higher and thus thermal runaway ?
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