Hi,
At first please clarify the expected function:
In your first post you wrote "MOSFET based Switch for ON and OFF".
Thus my first idea was a circuit like a bilateral analog switch fir signals...
But now it rather seems like a "low side power switch"
To your specifications:
A Mosfet needs to withstand:
* the maximum applied voltage V_DS --> in your case the supply voltage (plus some headroom)
* the maximum drain current --> in your case the load current (plus some headroom)
* the temperature = maximum ambient temperature + temperature rise caused by I_drain_RMS ^2 × R_ds_on
And yes, V_gs should be close to zero to switch OFF the Mosfet
And should be much higher thanV_gs_th but lower than V_gs_max to switch ON the Mosfet.
Mind: any inductance will cause voltage spikes during switch/OFF. You need to take care that this is less than V_DS_max .... in any case and even for nanoseconds.
Klaus
Vgs = 10V is good (low Rdson, low switch voltage drop), but the "on" operation point is not saturation, it's ohmic mode.Switch has two Position ie ,Cutoff and Saturation
So Cutoff = Vgs<Vth ---- = 0 volt ----> MOSFET OFF.
At switch Close Position ---> saturation
Vds>Vgs-Vth
So I takes Vgs as 10Volt .
V1 is the supply voltage, not Vds. Vds in on-state is in the mV range, both for V1 =10 and V1=12V.As per the ohmic and saturation region the plots shows no diffrents why so .
What is the wrong with me?
V1 is the supply voltage, not Vds. Vds in on-state is in the mV range, both for V1 =10 and V1=12V.
Should be considered ohmic range, isn't it.Measure the Vds when it ON it gives 12mv and 10.5mv for V1 =12v and V1 = 10 respectively.
You said that you want to "control" a 12V/2A bulb. To turn it on and off? The Mosfet datasheet says the Mosfet is off when Vgs is zero and it is turned on well when Vgs is 10V.[/QUOTE said:Thanks ,
But then Is the MOSFET works on cutoff and Ohmic region ?
or cutoff and stauration region?
Hai sir i don't have confusion as you said . I know ohmic or linear or triode region is the low resistance mode of the MOSFET operation. Where the condition also known Vds <Vgs-Vth.You are confused about Mosfet operation because you are using English terms for an ordinary transistor.
An ordinary transistor is linear when it is partially turned on. It is saturated when it is turned so that it has a low Vce.
But a Mosfet is said to be "saturated" when it is partially turned on and it is "linear" or "ohmic" when it is turned on so that it has a low Vds.
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