How to analyze this ACDC circuit?

kal9623287

How to analyze this ACDC circuit? [Copy link]

 

The following is an ACDC circuit. How does it work without a control chip? How is the transformer coupled to the secondary voltage?

maychang

[The following is an ACDC circuit. How does it work without a control chip? ]

Without a control chip, it may be self-excited. But I seriously doubt whether this circuit can work, because the capacitance on the gate of the MOS tube is as high as 47uF.

maychang

[The following is an ACDC circuit. How does it work without a control chip? ]

There is a component in the picture. It looks like a MOS tube, but it is marked as IC01. Such a mark is often an integrated circuit. IC is the abbreviation of integrated circuit.

maychang

[The following is an ACDC circuit. How does it work without a control chip? ]

There are control chips with power tubes, such as TOP227, which are packaged in TO220 and have only three pins, which are very similar to ordinary power MOS tubes. But its internal structure is quite complex, including oscillation circuit, pulse width modulation circuit, and power switch tube.

I guess the author of this picture couldn't find the symbol, so he used a ready-made MOS tube symbol instead. They all have three legs anyway.

maychang

[The following is an ACDC circuit. How does it work without a control chip? ]

Compare this electrical schematic with your own.

tagetage

The answers above are almost the same. There is an IC01 under the rectifier bridge, which is a control chip.

吾妻思萌

You didn't capture the whole picture.

The upper left part is the AC input, four diodes convert it into DC, and then the MOS tube or some IC controls it, and the transformer works.

Why is it called ACDC? This is AC-DC-AC.

maychang

Azuma Simeng posted on 2024-2-6 11:46 You didn’t capture the whole picture. The upper left part is the AC input, the four diodes turn it into DC, and then the MOS tube or some IC controls it, and the transformer works. ...

[Why is it called ACDC? This is AC-DC-AC, right?]

The transformer secondary of the first post circuit has four secondary circuits, all of which are connected to diodes and large electrolytic capacitors. The two circuits on the right are also connected to three-terminal linear regulators LM7805 and LM7824. Obviously, this circuit is not an AC output. If we must say that the upper left rectifier bridge has converted AC power into DC, then we should say it is AC-DC-AC-DC.

吾妻思萌

maychang posted on 2024-2-6 15:07 [Why is it called ACDC? This is AC-DC-AC] The first post circuit has four secondary transformers, all of which are connected with diodes and larger electrolytic...

[That should also be called AC-DC-AC-DC. ]

Teacher, what the original post said, ACDC means that the MOS switches on and off the AC, and then the transformer half-wave rectifies the DC, right?

吾妻思萌

maychang posted on 2024-2-6 15:07 [Why is it called ACDC? This is AC-DC-AC] The first post circuit has four secondary transformers, all of which are connected with diodes and larger electrolytic...

[If we must say that the upper left rectifier bridge has converted AC mains into DC, then we should also say AC-DC -AC-DC]

The previous red cross-straight is not mentioned much?

maychang

Azuma Simeng posted on 2024-2-6 16:26 [That should also be said to be AC-DC-AC-DC. ] Teacher, the original post said that ACDC means that MOS turns on and off the AC here, and then the transformer back end...

The first post mentioned AC-DC, I think it means from the AC mains on the far left (J01 and J02) to the 24V output on the far right (J07 and J08), no matter how many layers there are in the middle, just ignore them.

tagetage

Azuma Simeng posted on 2024-2-6 16:27 [It must be said that the upper left rectifier bridge has already converted AC mains into DC, so it should also be said to be AC-DC-AC-DC] The previous red AC-DC is not...

AC-DC-AC-DC, it's the two AC- DC-AC -DC in the middle, don't worry about it, it's just the initial input AC, the final output is DC. What the 11th floor said is correct.

无罪之宾

The ACDC converter, which controls a small power conversion power supply integrated with the power tube, is likely to use the TOP chip series.

qwqwqw2088

PI's top226 three-pin switch control chip, AC-DC conversion circuit

The start-up circuit is all internal, no external control pin is required

lugl4313820

I studied the 14th floor quietly, and the knowledge I gained is so broad.