Foldback current limiter circuit

In summary: BCM2835... mosfet part number is interchanged with the transistor part number... so it is BCM2835...In summary, the current limiting circuit has a max current limit of 3 Ampere and a short circuit current limit of 1 Ampere. The output voltage is 28 volts which is the same as the input voltage.
  • #1
basitccp
5
0
hi,

i want to design a foldback current limiter circuit whose max current limit is 3 Ampere and short circuit current limit is 1 Ampere. Also output voltage is 28 volts which is same as input voltage ... can anyone help me in this regard...

Thanks in advance...
 
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  • #2
basitccp said:
hi,

i want to design a foldback current limiter circuit whose max current limit is 3 Ampere and short circuit current limit is 1 Ampere. Also output voltage is 28 volts which is same as input voltage ... can anyone help me in this regard...

Thanks in advance...

Welcome to the PF.

It will be hard to design a current limiting circuit that has Vin and Vout the same. You would usually need to tolerate a few tenths of a volt across a current sensing resistor, and you will need a series pass transistor to serve as the cutoff element to lower the output current. How much voltage drop Vin-Vout can you tolerate?

Also, can the short circuit current limit be less than 1A? Otherwise your pass transistor must dissipate 28W in current limit...
 
  • #3
berkeman said:
Welcome to the PF.

It will be hard to design a current limiting circuit that has Vin and Vout the same. You would usually need to tolerate a few tenths of a volt across a current sensing resistor, and you will need a series pass transistor to serve as the cutoff element to lower the output current. How much voltage drop Vin-Vout can you tolerate?

Also, can the short circuit current limit be less than 1A? Otherwise your pass transistor must dissipate 28W in current limit...

Thanks..

Vout should not be less than 27.5 volts.. This is the maximum that i can tolerate when the circuit is behaving well. when it is in fold back condition obviously voltage drops. yup short circuit current can also be less than 1 Ampere there is no such limit but not more than 1 ampere..

i have design my circuit according to the attachment. but when the fold back of current starts mosfets gets very hot and then current again starts increasing because of overheating.. i have used heat sinks but still can't solve the issue. i have used 3 mosfets in parallel to reduce current i can reach a limit of 1.5 ampere max..
 

Attachments

  • 13694-Figure_1.pdf
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  • #4
also see the attachment

Thanks..
 

Attachments

  • foldback.pdf
    24.4 KB · Views: 340
  • #5
Have you labelled the type numbers on those two transistors correctly, basitccp?
 
  • #6
NascentOxygen said:
Have you labelled the type numbers on those two transistors correctly, basitccp?

sorry .. the part numbers are just replaced.
 
  • #7
basitccp said:
sorry .. the part numbers are just replaced.

mosfet part number is interchanged with the transistor part number...
 

1. What is a foldback current limiter circuit?

A foldback current limiter circuit is an electronic circuit designed to limit the amount of current flowing through a circuit, typically by reducing the voltage across the circuit. It is primarily used to protect electronic components from damage due to excessive current.

2. How does a foldback current limiter circuit work?

A foldback current limiter circuit works by using a feedback loop to monitor the current flowing through the circuit. If the current exceeds a certain threshold, the circuit will reduce the voltage across the circuit, which in turn reduces the current. This process is repeated until the current stays within a safe limit.

3. What are the benefits of using a foldback current limiter circuit?

One of the main benefits of using a foldback current limiter circuit is that it helps protect electronic components from damage due to excessive current. It also helps improve the overall stability and reliability of the circuit by preventing sudden spikes in current.

4. Are there any limitations to using a foldback current limiter circuit?

One limitation of using a foldback current limiter circuit is that it may cause a decrease in circuit performance due to the reduced voltage across the circuit. It is also important to ensure that the circuit is properly designed and adjusted to prevent false triggering of the limiter.

5. What are some common applications of foldback current limiter circuits?

Foldback current limiter circuits are commonly used in power supplies, amplifiers, and other electronic circuits that require protection against overcurrent. They are also used in industrial and automotive applications to protect sensitive components from damage.

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