gdylp2004
Member level 5
Hi guys,
I've attached a shunt linear regulator in attempt to provide a load regulation which consumes about 40mA in average. The regulated load voltage should be of 12V and thus a 12V Zener diode is chosen.
If we looked at the setup attached, there is a significant amount of power being wasted in R2 because of the high differential voltage of ~88V across V1 & cathode of Zener. So in order to reduce this wastage, the current through this resistor (R2) must be as low as possible, but not lower than the o/p current (which is 40mA for my case) + the knee current of the Zener.
And ensuring as low current through R2 also means that the I(z) must be also as low as possible. So my question is, is it correct to look for a Zener with the least test current since the knee current is never provided by the manufacturer and even if this information is valid, at I(z) = knee current, we would also expect that V(z) would most probably not maintained or regulated at 12V.
Also, is there anyway we could determine the di/dv characteristic from the datasheet like this one here: https://www.farnell.com/datasheets/69971.pdf
Thanks.
I've attached a shunt linear regulator in attempt to provide a load regulation which consumes about 40mA in average. The regulated load voltage should be of 12V and thus a 12V Zener diode is chosen.
If we looked at the setup attached, there is a significant amount of power being wasted in R2 because of the high differential voltage of ~88V across V1 & cathode of Zener. So in order to reduce this wastage, the current through this resistor (R2) must be as low as possible, but not lower than the o/p current (which is 40mA for my case) + the knee current of the Zener.
And ensuring as low current through R2 also means that the I(z) must be also as low as possible. So my question is, is it correct to look for a Zener with the least test current since the knee current is never provided by the manufacturer and even if this information is valid, at I(z) = knee current, we would also expect that V(z) would most probably not maintained or regulated at 12V.
Also, is there anyway we could determine the di/dv characteristic from the datasheet like this one here: https://www.farnell.com/datasheets/69971.pdf
Thanks.