Have recently been reading a on the forum, and other places about JFET transistors. I have a simple circuit with a variable resistor that can vary from 100 ohms and up, but for my application a range of 100 ohms to 200 ohms is all I care about (micro controller analog application).
So, I am wanting to replace the variable resistor with a P junction JFET, to act as a voltage controlled resistor which I can control with a gate voltage (ideally controlled by a micro also, so 0-5V range).
So as I understand it, to act as a linear voltage controlled resistor (ohmic/triode region), I need to keep Vds below a certain level. Then, I can vary Vgs, which will then linearly alter the value of the "resistor."
http://www.nxp.com/documents/data_sheet/PMBFJ174_175_176_177_CNV.pdf
I found this one because the Rds-on it has is slightly below what I need for my application (85Ω, and I need just 100Ω and up). My question is, where in the datasheet can I find the gate voltage that causes the current to "pinch off" (in the tutorial it is called Vgs cutoff) and the largest Vds I can have and remain in the ohmic region? I can't seem to understand the sheet exactly, especially since sometimes things are named differently.
So I want a transistor which will accurately have a varried DS "resistance" 100Ω-200Ω within the 0-5V range. Did I pick the right one? I hope I have provided enough information.
So, I am wanting to replace the variable resistor with a P junction JFET, to act as a voltage controlled resistor which I can control with a gate voltage (ideally controlled by a micro also, so 0-5V range).
So as I understand it, to act as a linear voltage controlled resistor (ohmic/triode region), I need to keep Vds below a certain level. Then, I can vary Vgs, which will then linearly alter the value of the "resistor."
http://www.nxp.com/documents/data_sheet/PMBFJ174_175_176_177_CNV.pdf
I found this one because the Rds-on it has is slightly below what I need for my application (85Ω, and I need just 100Ω and up). My question is, where in the datasheet can I find the gate voltage that causes the current to "pinch off" (in the tutorial it is called Vgs cutoff) and the largest Vds I can have and remain in the ohmic region? I can't seem to understand the sheet exactly, especially since sometimes things are named differently.
So I want a transistor which will accurately have a varried DS "resistance" 100Ω-200Ω within the 0-5V range. Did I pick the right one? I hope I have provided enough information.