Hi,
You need two things:
* generate the 5V
* and current limit them
There are 5V regulators. They will "generate" clean 5V.
For current limit: (two simple ways)
* either choose regulators with current limit feature (infinite short circuit duration)
* or add a polyfuse in series with the 5V line.
There are many other possible solutions.
Klaus
No circuit can prevent an output to become shorted by a user.A polyfuse would still allow the circuit to be shorted, wouldn't it? and so the power would go off.
This might be a different issue, simply adding resistance in the supply rail increases it's impedance and is likely to make the amplifier unstable. You could try adding a capacitor (~100uF) across the rails AFTER the limiting resistor (on the op-amp side) to reduce the impedance.What actually happens is that the output of the op-amp circuit , which is configured with some gain and a 2.5v swing around zero, starts to pulsate.
Before the regulator it can just be a resistor but, as betwixt mentioned, the difference is that the resistive drop will have no impact on output voltage until right when it reaches the limit.
For example if its a 12->5V regulator you can put an R on the regulator input. 100 ohms would be a roughly 70mA limit (not factoring dropout). The 5V output will be perfect until the input voltage of the regulator drops to its input limit, perhaps 5.5-7V.
There are also millions of 5V current limiting IC's which are essentially solid state fuses:
https://www.maximintegrated.com/en/products/analog/analog-switches-multiplexers/MAX4789.html
Note you mentioned poly-fuses earlier: be careful, they're great in theory but in practice they're pretty poor (very wide temperature variation, high trip current, low hold current etc). The above IC or one like it may be nearly as cheap/small.
Do you know what the input voltage is to the 5V regulator?
That determines the maximum resistor you can use at the regulator input to limit the current.
Depending on the regulator dropout voltage, that means you can have only about 2-3V drop in any current limit resistor in series with the regulator input.Yes, it is 9.9 volts
The voltage needs to be current limited so that a user does not inadvertently short the supply
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?