Timeline for Precise Current Limiting for Variable 0–300VDC Supply
Current License: CC BY-SA 3.0
17 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 25, 2017 at 2:36 | comment | added | Jack Lynch | @BruceAbbott that sounds great. Is there a simple modification to the circuit in the accepted answer that would implement this method of "fold-back" current limiting? | |
| Apr 25, 2017 at 1:45 | comment | added | Bruce Abbott | A 50mA fuse will blow somewhere between 60mA and many amps, depending on the type of fuse and how long the over-current event lasts (at 50mA it should never blow, at 60mA it might take several minutes or even hours). An 'electronic fuse' may be much faster, but will still have a response profile. Another method is 'fold-back' current limiting, where after tripping the current is limited to a lower value until the load is reduced. | |
| Apr 25, 2017 at 0:54 | answer | added | Brian Nebeker | timeline score: 0 | |
| Apr 25, 2017 at 0:51 | comment | added | Jack Lynch | @replete oh... is there a way to modify it so that it cuts off instead of entering constant current mode? Could I just add, say, a 50-mA fuse on the end? | |
| Apr 25, 2017 at 0:22 | comment | added | user133493 | Note that the answer that you accepted (excellent though it may be) enters constant current mode rather than disconnecting the supply which you said was your desired functionality. | |
| Apr 23, 2017 at 17:38 | vote | accept | Jack Lynch | ||
| Apr 23, 2017 at 17:37 | comment | added | Jack Lynch | @replete I would hold regulation of the output voltage above all else. There will be maybe 20 loads, all of the same type | |
| Apr 23, 2017 at 15:00 | history | tweeted | twitter.com/StackElectronix/status/856160971978661888 | ||
| Apr 23, 2017 at 13:23 | answer | added | D.A.S. | timeline score: 0 | |
| Apr 23, 2017 at 10:16 | answer | added | Bruce Abbott | timeline score: 4 | |
| Apr 23, 2017 at 7:43 | comment | added | user133493 | How tightly regulated must the output voltage be? What are the expected loads? The wider the variety of loads connected to a power supply, the more difficult is the design of its control loop. If you will only use specific loads, such as tubes, this simplifies the design. I realize your question is about current limiting but these subcircuits will interact. | |
| Apr 23, 2017 at 4:37 | history | edited | Jack Lynch | CC BY-SA 3.0 |
added desired behavior if maximum current tolerance exceeded
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| Apr 23, 2017 at 4:36 | comment | added | Jack Lynch | @TonyStewart.EEsince'75 Let's go with 5mA tolerance, cost below $50 (unless that makes no sense, in which case, what does seem feasible?) and power dissipation at whatever seems best to you. Can I handle larger power dissipation by adding something like a heat sink? If so, anything's fine—I'm not space-constrained. | |
| Apr 23, 2017 at 4:26 | comment | added | Jack Lynch | @replete I'd definitely want to cut off above the maximum | |
| Apr 23, 2017 at 4:16 | comment | added | D.A.S. | You specified 3 parameters with no tolerances, making this unsolvable. Pls define now, 50mA tolerance, cost tolerance and power dissipation design assumption. | |
| Apr 23, 2017 at 3:50 | comment | added | user133493 | The first step is to define the behaviour you want upon reaching current limit. Remember that if you want a constant output voltage, the output current is determined by the load. Current limiting circuits can transition into constant current mode when the maximum permissible current is reached, by varying the output voltage. On the other hand, given the dangerous voltages present here, you may decide that if the current limit is exceeded, the supply should be disconnected. Which behaviour do you want? | |
| Apr 23, 2017 at 3:42 | history | asked | Jack Lynch | CC BY-SA 3.0 |