Induction Heater with CKM005 Microcontroller
UPDATE 11/7/12 – More pics of device and full disassembly uploaded by Ad. Thanks!.
A user nicknamed “Ad” has taken some pictures of the inside of a new induction cooktop by Better China, see their original comments at this article. This device is interesting because it appears to be a streamlined version of the Burton cooktop we looked at, with many fewer devices and one big, 20-pin mystery chip as the brains of the device. With the posted pics and a little detective work we’ve found out a bit more about this device and will now share it with you, fine readers.
Check out the full story in the very beautiful pics Ad took. Great work, and awesome camera by the way!
First, we will start out by showing the new pics Ad uploaded, then we’ll continue on with the rest of the article from yesterday. First, the image from the box.
We see the control board with 7-segment LED display for temp and power readout up in front. The obligatory fan mounted down in the base of the unit, and a lovely induction coil. Looks like about the same gauge Litz wire as the Burton unit but with a much nicer coil former. We’re hoping it’s not all glued together in a big shellac clump like the Burton, so the coil can be disassembled and re-wound into a cylinder! Aside from the melted black plastic formers, it APPEARS there’s nothing too troublesome holding the coil in place, which is a very encouraging sign.
Next comes the power stage board. Again, very clean and simplified design. There’s the input filter/current feeding inductor up there in the upper left, the nice hefty blue caps for the resonant tank and feed tank, and MANY fewer components than the Burton. Compact, and probably much cheaper to produce.
Ahh, the big boy himself. The venerable 25N120 IGBT. 25A and 1200V of pure power switching fury. A little slow for chopper based converters, but for this type of high current soft-switching application this device cannot be beat. It’s interesting that this cooker gets away with only a single IGBT – not sure if it’s lower powered than the Burton, or whether only a single IGBT is needed to get enough power over there in 230V land. Lucky bastards!
Here’s the solder side of the power board.
Again, cleaner and more compact. And nicely diagrammed in white silkscreen to make circuit tracing easier! Excellent! Ad has been kind enough to label a few of the power stage components for us in red, along with their values.
So that’s it for the extended tour of the insides of the new device. We’ll continue on with the remainder of the original post from yesterday as we puzzle out the function of the power stage. But rest assured, we are now opening eBay and looking for this little gem to see for ourselves what treasures it holds.
Let’s take a look and see what we can recognize. We can see the heatsink, presumably cooling the bridge rectifier and IGBTs, as well as the big fat resonant caps (light blue). The same old 8-pin flyback IC appears near the little yellow transformer, probably making the same old 18V (or 12V) main rail for running the gate driver of the IGBT. And is that the good old 7805 linear regulator? Must be the same old 5V rail for the control circuitry. But no LM339? And no ratsnest of discrete components to do the voltage sensing, current sensing, PWM, fault protection, etc? Cool!
It appears to have all been replaced by a 20-pin mystery IC with the “200D-BUP” label. This code is probably the model number (200W? or 230V?) and revision code for the cooker. Now… What’s beneath this little lady’s skirt? Ad obliges to give us a peek in this next pic.
For more detail: Induction Heater with CKM005 Microcontroller
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