I found a problem in my design and I can't find any solution to fix it.
My charger module with LTC4015 can start to charge the 7cells li-ion battery at 3.2Amp (10 mOhm RNSB). However, after 20-30 second, the charger stop charging and the VIN mosfet turn off (battery current is negative) . Then, the charger get back to charge again then stop. The loop time became shorter than the first loop.
I keep observe on IC's register via I2C bus and I found that when I turn-off VIN, it seems the IC can't interface via I2C. Data from I2C is not correct and some register always zero.
The IC will be back to communicate via I2C when I turn off all power source (VIN and VBatt) and turn on.
What should I try to solve this problem ?
Thank you in advance
Yes, I have a list of notes specific to laying out the LTC4015. I've attached it here.
In general for you, add more GND pad vias and move critical components as close to the IC as possible.
Sounds like a noise issue interfering with charging. This is usually caused by layout issues. Can you please share your layout? PDFs would be preferred.
Please find the attached file.
I found something for observation, if I remove the C24. the charger works fine but the charge current is not 3.2 A, it's 2.8 A.
Ps, I couldn't attach a file. Then, I sent you in private message instead.
C24 is the 2P5Vcc cap, right? You removed it and the charger works?
Do you have vias on the GND pad of the IC? You should have a grid of vias but I don't see them on the layout.
Yes, C24 is 2P5VCC cap. I removed it and the charger works but I2C doesn't operate. However, I try to add 10 Ohm series to 2P5Vcc cap and all works fine.
I have a plan to revise this but I don't know what should I consider to adjust. Any suggestion from you ?
attached is the image file for GND pad with via under IC.
Thank you. I will re-design our PCB layout then I will be back to give feedback here.
Before you submit your design for fabrication, feel free to run it by me. You can send the full layout to me in a private message if you like (PDFs preferred). Or you can post as a continuation here.