Tizana
Newbie level 6
Hi,
I'm about to make a circuit which should drive an LED strip from a 3.3V microcontroller using an NMOS and PWM.
the Nmos trasistor that i chose is this one IRLML2502 , https://www.infineon.com/dgdl/irlml2502.pdf?fileId=5546d462533600a401535667f44d2602
my question are as follow :
1- i want to know if i apply a Vgs>Vth(Threshold), the current Id will be imposed by Vgs or it will be imposed by the load connected to the drain ?
Because according to the transfer characteristic curve, for each Vgs we have a current Id, so for a Vgs = 3.3V the Id is equal to 32A. see the curve bellow :
and the 32A is a way above the current supported by the transistor.
For example the load may vary in my application, for example the circuit can drive 4 LEDs as he can drive also 8 or more LEDs, so the current may vary depending on the load knowing that Vgs is fixed to 3.3V .
2- another question related to the output curve Vds/Id :
normally when the NMOS work as a swtich it should be operate in the cutoff region or in the saturation region.
Cutoff = Nmos Blocked,
Saturation = Nmos ON,
and normally in the saturation region when the transistor is on, the Vds voltage should be as close as possible to zero but according to the output curve, in the saturation region the Vds is way far from Zero.
any explanation ?
thanks
I'm about to make a circuit which should drive an LED strip from a 3.3V microcontroller using an NMOS and PWM.
the Nmos trasistor that i chose is this one IRLML2502 , https://www.infineon.com/dgdl/irlml2502.pdf?fileId=5546d462533600a401535667f44d2602
my question are as follow :
1- i want to know if i apply a Vgs>Vth(Threshold), the current Id will be imposed by Vgs or it will be imposed by the load connected to the drain ?
Because according to the transfer characteristic curve, for each Vgs we have a current Id, so for a Vgs = 3.3V the Id is equal to 32A. see the curve bellow :
and the 32A is a way above the current supported by the transistor.
For example the load may vary in my application, for example the circuit can drive 4 LEDs as he can drive also 8 or more LEDs, so the current may vary depending on the load knowing that Vgs is fixed to 3.3V .
2- another question related to the output curve Vds/Id :
normally when the NMOS work as a swtich it should be operate in the cutoff region or in the saturation region.
Cutoff = Nmos Blocked,
Saturation = Nmos ON,
and normally in the saturation region when the transistor is on, the Vds voltage should be as close as possible to zero but according to the output curve, in the saturation region the Vds is way far from Zero.
any explanation ?
thanks