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MOSFET (Si/SiC) Forum Discussions

lil_Explorer
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Hello everyone,
I want to create a circuit with 24V supply that is limiting the current to 8A. This circuit should not have a greater voltage drop than 1V.  I don't find anything to use on the Internet. I would like to use MOSFETs or Transistors in the circuit. My specifications are that I should not use any mechanical construction parts.
I would really appreciate any helpful tips.

Kind regards

lil_Explorer

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1 Solution
Meghana
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Moderator

Hello @lil_Explorer ,

A discrete solution can be used similar to the circuit given below, but it can be bulky and the accuracy could be lower. 

Rshunt & Vref are to be designed according to the limit of 8A. RC combination at the output of the differential amplifier (R1 & C2) should be designed as per the minimum pulse width at which you would like to trigger the protection function.

You may select suitable MOSFET from below link.

https://www.infineon.com/cms/en/product/power/mosfet/p-channel/?filterValues=~(869_max~(leftBound~-8...

Meghana_0-1663416011547.png

Alternatively, you can also consider using PROFET™, Smart High Side switches which come with integrated current protection limits which can be tuned as per your application needs. 

Please check through both the options and let us know your preference, we can further help with the detailed design. 

Regards

Meghana 

 

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Meghana
Moderator
Moderator 250 sign-ins 50 solutions authored 5 likes given
Moderator

Hello @lil_Explorer ,

Thank you for posting on Infineon developer community. 

Yes. MOSFETs can be used as a relay and can be controlled based on the system limitations. Can you please share us some details about your application, which will help us in suggesting right solution. 

1. What is the source of this 24V ? Is it a battery or a regulated supply? 

2. Are you planning on having a digital controller for the system diagnostics or are you looking for an analog hardware control for current limitation. 

3. What is the type of load connected to this system.

Regards

Meghana

 

 

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lil_Explorer
Level 1
First reply posted First question asked Welcome!
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Hello Meghana,
thanks for your response.
1. The circuit uses a regulated 24V supply.

2. I am searching for an analog hardware based solution for current limitation.

3. The load connected to the system is among others fans. These draw high current during their start-up. Which should be limited. The limitation should stay for the whole time and should allow short current peaks to pass.


Regards

lil_Explorer

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Meghana
Moderator
Moderator 250 sign-ins 50 solutions authored 5 likes given
Moderator

Hello @lil_Explorer ,

Just one clarification before we suggest the solution. 

1. Is 8A the limit that you would like to set for the start-up current? Meaning you want to disconnect the load if their start up current exceeds 8A? 

2. Short current peaks-- By term 'short', are you referring to the amplitude of the current or the pulse duration? 

We will get back to you with a sample circuit. Meanwhile, please clarify above points.

Regards

Meghana 

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lil_Explorer
Level 1
First reply posted First question asked Welcome!
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Hello @Meghana,

1. That's right, 8A is the current limit I want, but it is important that the voltage drop is not that high.           I need an output voltage above 22V. 
1.2 I think so. The current should have an average of 8A. So if the current exceeds the 8A the load will be    removed and if the current drops below the 8A the load will be reconnected.

2. I am referring to the pulse duration.

Thanks for the outstanding support.

Kind Regards

lil_Explorer

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Meghana
Moderator
Moderator 250 sign-ins 50 solutions authored 5 likes given
Moderator

Hello @lil_Explorer ,

A discrete solution can be used similar to the circuit given below, but it can be bulky and the accuracy could be lower. 

Rshunt & Vref are to be designed according to the limit of 8A. RC combination at the output of the differential amplifier (R1 & C2) should be designed as per the minimum pulse width at which you would like to trigger the protection function.

You may select suitable MOSFET from below link.

https://www.infineon.com/cms/en/product/power/mosfet/p-channel/?filterValues=~(869_max~(leftBound~-8...

Meghana_0-1663416011547.png

Alternatively, you can also consider using PROFET™, Smart High Side switches which come with integrated current protection limits which can be tuned as per your application needs. 

Please check through both the options and let us know your preference, we can further help with the detailed design. 

Regards

Meghana 

 

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lil_Explorer
Level 1
First reply posted First question asked Welcome!
Level 1

Hello Meghana,
thank you for your help and the suggestions you send me. The circuit is close to the parameters i set. I can do the last steps on my own. 

Best Regards

lil_Explorer

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Meghana
Moderator
Moderator 250 sign-ins 50 solutions authored 5 likes given
Moderator

Hello @lil_Explorer ,

Noted your feedback. Please feel free to reach out to us if any further support is needed on this topic.

Regards

Meghana

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