Current regulator

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flounder
 
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Joined: Wed Sep 18, 2013 9:10 pm

Current regulator

Post by flounder »

Here’s the general problem: I want to regulate the current for voltages in the range 3.3-50V and limits from 100mA-10A.
More specifically, I do not need one device that can cover this entire range. I might need <[email protected] and I might need 10A@36V, and these could have completely different components. For any single project, I will need (n)A@(m)V, where n and m will be fixed for the life of the project. A resistor is not the answer because the load will not be constant; I just don’t want to exceed a certain current, and for the 10A load, I ² dominates the I ² × R formula and the power dissipation (and heat and wasted energy) becomes a problem. I have not had luck finding circuits that can handle more than about 1A. Pointers to resources would be appreciated.

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mikeysklar
 
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Re: Current regulator

Post by mikeysklar »

Have you looked into capacitive based charging? It is pretty much just stacking capacitors in parallel. It is a lot safer if you can use a step down transformer in instead of an AC + bridge rectifier setup.

https://en.wikipedia.org/wiki/Capacitive_power_supply

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adafruit_support_mike
 
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Re: Current regulator

Post by adafruit_support_mike »

The general solution is to have multiple regulators that can work in parallel, with relays that swap them in and out of the output path as required by the load. You can often hear bench supplies click as they bring different sections into play.

You’ll also want switched filters on the output. The amount of capacitance necessary to keep a 50V @ 10A line reasonably stable would continue to power a 100mA @ 3.3V citcuit for several seconds after you shut off the regulator itself.

Partitioning the maximum current load into a set of smaller values is kind of free-form.. some people would suggest a 1-2-5 series, others would say to use 1-2-4-8, others would suggest something else. In general you want to keep the output current between about 25% and 75% of what the active supplies can do. Below about 25% small adjustments tend to get fiddly, and above 75% you lose headroom for things like transient response.

Analog/Linear are the reigning champions of power supply ICs, so check their products and read as many datasheets as you can. They don’t just list general specs, they tell you how the devices work and how to use them effectively.

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