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# How does foldback current limiting work?

## How does foldback current limiting work?

Foldback current limiting actually decreases the output current under overload conditions. As load current increases, the voltage drop across R1 increases, as it did in the constant current circuit. If the load current increases past a certain threshold, the circuit will “fold back“ the output current.

## How do you limit electric current?

Current limiting components

1. Fuse and Resistors. These are used for simple limiting of current.
2. Circuit Breakers. Circuit breakers are used to cut off power just like the fuse, but their response is slower and might not effective for sensitive circuits.
3. Thermistors.
4. Transistors and Diodes.
5. Current limiting diodes.

How do I reduce the current on my power supply?

Lowering amperage is done by applying Ohm’s law, given by the formula I = V/R, where I is the circuit’s total current in amperes, V is the voltage and R is the resistance. Add resistors to the circuit to increase the total resistance. A higher resistance results in a lower amperage.

How can we decrease current?

The current in a circuit is directly proportional to the electric potential difference impressed across the circuit and inversely proportional to the resistance of the circuit. Reducing the current can be done by reducing the voltage (choice A) or by increasing the resistance (choice D).

### Does voltage limit current?

Absolutely. The resistance of a ‘short-circuit’, including the contact resistance from the supply terminals to the wire, is not zero, but finite. If the supply is being asked to deliver (say) 1v to a 0.1ohm resistance, then ideally it would take 10A.

How do you limit short circuit current?

Limiting short-circuit currents In order to limit the short-circuit current at the same voltage level, the only method is to increase the inductive reactance seen at the fault location. This can be done by either increasing the inductance of the circuit, or by removing parts of the circuit from the fault path.

What is frequency foldback?

Frequency foldback refers to decreasing the PWM’s oscillator frequency dwring short circuit or overload conditions and allows the duty cycle to decrease below the value normally limited by the total propagation delay.

## What is the use of foldback current limiting?

Foldback current limiting method is one such overcurrent protection scheme. Foldback current limiting technique reduces the output voltage and output current linearly during overload and overcurrent conditions, bringing the power dissipation under limits. Consider a linear power supply with input voltage Vi, output voltage Vo and output current Io.

## How many types of current foldback circuits are there?

The main 3 types of current foldback circuits are: The lack of accuracy of the current foldback circuit can be corrected by including a current limiting scheme in the circuit. In this current protection, whenever the current crosses the threshold limit, it moves to constant current limiting mode.

What happens at the end of the current foldback curve?

Following that, the output current reaches the end of the current foldback curve, which is as well the beginning of the current limiter curve (see V3, I3). The output current hardly increases any further, while the output voltage ramps up to its set value.

What are the limitations of the foldback method?

Although foldback allows the use of a smaller series pass element, it has its limitations. As the foldback ratio, I K /I SC, is increased, the required value of R SC increases and this calls for a greater input voltage at high foldback ratios. There is an absolute limit to the foldback ratio when R SC is infinite of FIGURE 7.17.