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At 0 volts (or close to it) the regulator is going to have to dissipate 150 watts of power... A simple buck switch mode supply before the linear regulator can help this dramatically. But if you can't tell by the odd English that the user said they designed a 0-30V 5amp linear supply but they want us to supply the diagrams that something might be wrong with the original posters intentions...
There are a couple of advantages to regulating the negitive rail. To me the most important is that it is easy to measure current in the low side so you don't need a special circuit to measure current in the high side.
Hi Umma,
I don't think it is a good idea to change the 324 with a 339 because the circuit may become unstable with the higher gain/bandwidth.
...but how do you implement the adjustable current limit like the bottom one on the high side.
With a diff amp.
...but I have always found that to be less practical for simple reasons:
1) You usually develop very small voltage drops across the current sense resistor (like 50 - 100 mV) to reduce power dissipation there and save wasted voltage drop.
2) This means the diff amp has to be a pretty expensive and precise one to avoid adding serious gain errors to that voltage. The cheap op amps (like I use) have several mV of input offset voltage).
You completely missed the point. I was saying that power considerations make the source voltage low which requires the gain blocks after it to have high precision. You want to use as few amp stages as possible after the sense resistor.The I²R and voltage loss would be the same be it in the "top" or "bottom". .
No, you certainly don't. You use the inside voltage point (negative side of the resistor in the negative return line) as a negative going signal to feed directly to an error amplifier for current control or current limiting. The level shifting diff amp is not used. believe me, I have deigned a few dozen of these.$$$$$ goes along with performance. To do it "properly" in the low side, you would need a diff amp a well.