Other Parts Discussed in Thread: BQ40Z50-R2,
We are seeing a similar phenomena reported by other users at the end of charging. The STAT1 signal constantly cycles between low and high about every 2 seconds. The STAT2 signal always stays high. (STAT1 is low for about 140msec during every ~2 seconds cycle.)
We are using BQ24610 to charge a smart battery pack. The battery pack uses the BQ40Z50-R2 fuel gauge. The battery pack has the charge termination current set to 0.35A so that it shuts off charging before the charger does. (The BQ24610 termination current is set to 0.3A) The reason is (I am told) that the fuel gauge needs to end the charging process in order to accurately set the SOC to 100%.
When the fuel gauge shuts off charging, we believe the charge FET inside the battery pack turns off. When that happens, the external no-load battery pack voltage drops about 0.5V (diode drop + battery relaxation) lower than the charging voltage. This voltage is slightly lower than the Vrech threshold, so the battery charger circuit tries to recharge the battery. But the battery is shut off from charging. This results in an endless cycle. We have never seen the BQ24610 outputting the "Charge Complete" status.
1. What is the best way for the charger IC and fuel-gauge IC to work together and implement charging termination properly?
2. How do we get the BQ24610 to output the "Charge Complete" status at the end of charging?
3. The BQ24610 TTC pin is currently connected to a 0.1uF capacitor. Do you recommend grounding this pin in order to disable charger termination? Would this help?
4. Do you offer another charge controller IC similar to the BQ24610 that works better with the fuel gauge IC BQ40Z50-R2?
Thank you...