Hello,
I am a student and I am currently trying to interface the LM3658 charger with a MSP430 microcontroller. I have connected STAT1 and STAT2 to the controller and I have enabled its internal pull-ups (since STATx are open-drain outputs). The problem is that STAT1 pin fastly switches low and then high again when no battery is inserted. This causes many interrupts on the microcontroller.
In order to figure out this problem, I looked at the waveforms on the LM3658's pins and I realised STAT1 goes low (and suddenly high) when the voltage on BATT pin spikes. The question now is why these voltage spikes are present on BATT pin.
This is the schematic of the charger I have used for my project:
As you can see, only USB power is used to charge the battery.
These are the changes I have done to the circuit trying to solve the problem:
- adding a 1µF capacitor on CHG_IN
- adding a 10kΩ pull-down resistor on ISET
- changing C32 (the 1µF capacitor on BATT pin) with an electrolytic one
I do not have much time to spend on this problem, because I must finish this project as soon as possible. That is why I am asking here for some help.
Thank you.