M54128 Earth Leakage Current Detector

Discussion in 'General Electronics Chat' started by kevindd992002, Nov 23, 2010.

Nov 23, 2010
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Can anyone please help me on what function does the M54128 Earth Leakage Current Detector do? I don't quite understand what it does based on the datasheet: http://pdf1.alldatasheet.com/datashe.../M54128FP.html provided by Renesas/Mitsubishi.

I'm in the process of doing an Analysis and Simulation job in my company but I'm new to this. I have the circuit of the whole chip but am having a hard time analyzing it.

Any help would be much appreciated. Thanks.

2. thatoneguy AAC Fanatic!

Feb 19, 2009
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It appears to be part of a GFCI (Ground Fault Circuit Interrupter) to kill the circuit when current from hot doesn't match current in neutral.

Possibly also an Arc Fault Detector, possibly both. The datasheet I looked at (your link didn't work for me) stated:

Nov 23, 2010
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Hmm. Well, I have the whole chip circuit with me (transistor level) and my task is to analyze how it works. I'm having a hard time though because it is my first time to analyze a whole chip circuit. I also have Cadence to simulate it.

Would it be possible for you guys to help me analyze each block of this IC?

What does earth-leakage exactly mean? Is this unwanted current that flows to ground?

4. thatoneguy AAC Fanatic!

Feb 19, 2009
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It means current is taking a path to ground other than on the neutral return conductor, such as when somebody has one hand on a live wire, and the other on a cold water faucet. It must be interrupted within 5-20mS to minimize chances of cardiac arrest.

Nov 23, 2010
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Thanks for the info. Now I understand the function of the chip in a general sense. But I need to go in-depth looking into Transistor Level and to the expected input and output graphs presented in the datasheet.

Can you guys help me in analyzing how it works by explaining the graphs presented in page 6 of the datasheet of this chip?

6. thatoneguy AAC Fanatic!

Feb 19, 2009
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718
This Datasheet may explain it better

It is the Mitsubishi DS with quite a few good pages, breaking out subcircuits, etc. The IC itself only detects the earth fault, the high voltage side of the GF/AFCI takes care of providing the signals to the IC and using the signals from the IC to break the circuit.

Nov 23, 2010
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Actually that is the datasheet I was looking into for a while now. Would it be possible for you to explain each subcircuit?

8. thatoneguy AAC Fanatic!

Feb 19, 2009
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Which part do you not understand?

We have a few guys here that have worked directly with chip design and fab if that is the sort of advice you are looking for, one of them should stumble across the thread I would think.

Nov 23, 2010
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I'm prohibited to actually post the reverse-engineered circuit as it is intellectual property of the company, would it be possible to send the schematic directly to you through PM? Or any of you guys, with experience in chip design, willing to help me in this?

Thanks.

Apr 5, 2008
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Hello,

We do not give support to reverse-engineerd circuits.
You will have to publish the circuits you want to discuss or don't discuss it at all.

Bertus

Nov 23, 2010
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Hi bertus. What do you mean I need to publish them?

Thanks.

Apr 5, 2008
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Hello,

We can only give good advice when we can have a look at the schematics.
Without any schematic it is very difficult to give an answer.

Bertus