I am finishing the design of a device to manufacture.
But I am having a serious problem with the IC MP2639A when charging.
I use an STM32L4 microcontroller to detect that the USB charging port is connected and thus activate the battery charge and read the status of the MP2639A leds to see how charged/discharged the battery is.
It is a 2S battery. If I don’t connect the balance of my battery to the MID pin (chip balance) nothing happens and it seems that the charge is carried out correctly. But if I connect the balance pin and go from charge to discharge and back to charge, the battery doesn’t charge and even discharges one of the cells.
I have added the resistor in the MID pin so that it does not discharge/charge at more than 200mA but I do not get anything more than to discharge the lower cell. As specified in the datasheet, the MP2639A balances the battery when there is more than 65mV difference between one cell and another, but it is not.
I am taking into account the pins of MODE = 0 to charge and MODE = 1 to discharge. In addition to taking into account the /PB pin to enable and disable the discharge.
If I remove the battery and discharge the MP2639A, everything works fine again. I have also read in the technical forum that it is necessary to discharge the pin from MID to GND but I can’t get anything. I don’t know if it is a recurring problem and it was fixed with the MP2639C model but unfortunately there is no stock and I urgently need to find a solution.
If someone could help me, it would be fantastic, because if it is a product that will go on the market, the balance pin is necessary to make it something safe.
Thanks in advance
