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| CN3722 is not working |
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| aakash dey:
I want to charge a 2-cell Li-ion battery with CN3722 charging IC. According to my circuit design, the float voltage at the battery terminal should be 8.4V. But, the float voltage is measured as 13.44V when input is of 15V. Also, when I connect the battery,it draws 220mA current for 1 second and after that it goes to 0A. Any idea, why this charging circuit is behaving like this? |
| ebastler:
Have you produced a PCB from your (Eagle?) schematic, or hand-wired the circuit? If you created a PCB, it cannot work because your schematic is missing many junctions. (Two wires meeting does not mean that they are connected. You need to place a "dot" at the connection point. If you use Eagle's "net" function to draw connections, it should place those juntions automatically, but you can also add them manually via the "junction" tool. Please use Eagle's ERC = Electrical Rule Check and look at the results carefully, to check for missing connections and other errors in drawing the schematic.) If you hand-wired the circuit, have you checked very carefully that you have indeed made all connections, and don't have any unintended shorts? I would venture a bet that you will find some error(s) when you look again! |
| aakash dey:
But, I have checked the schematic connection and also checked the brd file. I am attaching the brd file. You can easily understand from this. Please check the brd file. |
| ebastler:
The layout looks a bit awkward, but you are right, the connections seem to be there. (At least at first glance, and to the extent the screenshot lets me see them.) What program did you use -- is it indeed Eagle? Did you draw additional traces manually to make all connections? I can't understand why Eagle would know about the connections without the junctions in the schematic. How did you produce the PCB? Did you etch it yourself, or have it made by a PCB manufacturer? In either case, have you checked for unwanted shorts between the copper traces? Some of the distances seem awfully narrow, especially between the IC4 pads. |
| tsman:
What is R10 on PGND for? That isn't in the typical application circuit in the datasheet. |
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