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BQ24192: BQ24192 default register settings and Charging functionality when battery is fully discharged
Part Number: BQ24192 Hicompany Team, We are using BQ24192 as a charger and BQ27542 as Fuel Gauge and ABLIC 8211C as a Protection IC. We are facing one issue - For Ex - Battery is Fully discharged and reached the 3.1V when we Power ON the Unit then Battery charger apply 4.208V by default and ABLIC IC's charging Mosfet gets Off which is connected with CHG Pin and that may be because of Charge overcurrent condition detected because we have used 10mE resistor on Fuel gauge circuit in the series. Now I have a few questions - 1. How can we change pre-charge to fast charge threshold from 3V to 3.3V in the case of Battery charger BQ24192? 2. When we are changing the register settings and making the fast charge current to 100mA by setting up the 20 Percent bit then we are not facing this issue but how can we ensure that Battery charger is up by our set register settings? 3. Basically, what we have seen is that when Battery charger initially applies 4.2V and 2A fast charge current then this condition occurs but what we shall do to prevent this condition and battery charger applies less voltage and less current initially up to 3.3V and then gradually increase the voltage and current? 4. Is it possible that we shall change the default register settings at the time of initialization? Thanks Saumil
Saumil, The threshold is fixed internally. Disable watchdog timer by setting WATCHDOG bits REG07[5:4]=00 /CE pin can be pulled high to disable charge initially then pull low to charge when ready. Default values can’t be changed. Thanks, Ning.
Hi Ning, Ok, thanks for your response. Sr No - 1,3 and 4 are Ok. Now for Sr No 2, Regarding the Watchdog timer for Host Mode and default autonomous mode, 1. If I disable the Watchdog timer then Host needs to control the charger for the entire charging cycle? for example - If the host writes certain registers for fast charge current but when the Battery voltage reaches near to the charge voltage then transition from CC mode to CV mode and reduces the current gradually decides by charger or Host need to control that entire cycle? 2. While during the write cycle of I2C register, if charger enters into the Host mode then and the Watchdog time expiration occurs then, the registers that host has written been again set to default or it will remain the same? 3. At the Power ON/OFF state, host initialized the charger with the register settings and then host goes into sleep mode then what will be the register settings? Thanks Saumil
Saumil, 1. The device has built-in control loops to determine the transition from CC to CV. The host does not need to do anything. 2. Referring to Figure 25. Watchdog Timer Flow Chart on the d/s, if watchdog timer expires, the device will be in default mode and all the registers are in the default settings. 3. Please refer to Figure 25. Watchdog Timer Flow Chart. If the user would like to keep the register settings unchanged while the host is inactive, it is better to disable watchdog timer by setting REG05[5:4] = 00 before the host goes to inactive. Thanks, Ning.
Hi Ning, Ok, It seems to resolved my issue. Thanks Saumil
Hi Ning, I have tricky questions on this Watchdog functionality. 1. We are successfully able to run the charging cycle by Host and for that, we are using the Watchdog Timer disable functionality and we are selecting the Charging current by our Own. 2. We have created Some Voltage loops in that we are reading the Voltage from Fuel gauge and we are deciding on the charging current for the Battery charger. 3. For 2.8V to 3.2V, we are supplying the 140mA current for charging. 4. We have one Power ON/OFF button as well that can turn off the Host but battery can still remain present and connected with the Battery Charger. 5. Now, my query is that if the Charger is in 140mA charging current state and we are disabling the Watchdog timer also and if the user has turned off the host via Power ON/OFF button, then Charger may remain present in this 140mA state only or is there any way such that charger may start functioning with the fast charge current as well automatically? Thanks Saumil
Hi Ning, I have tricky questions on this Watchdog functionality. 1. We are successfully able to run the charging cycle by Host and for that, we are using the Watchdog Timer disable functionality and we are selecting the Charging current by our Own. 2. We have created Some Voltage loops in that we are reading the Voltage from Fuel gauge and we are deciding on the charging current for the Battery charger. 3. For 2.8V to 3.2V, we are supplying the 140mA current for charging. 4. We have one Power ON/OFF button as well that can turn off the Host but battery can still remain present and connected with the Battery Charger. 5. Now, my query is that if the Charger is in 140mA charging current state and we are disabling the Watchdog timer also and if the user has turned off the host via Power ON/OFF button, then Charger may remain present in this 140mA state only or is there any way such that charger may start functioning with the fast charge current as well automatically? Thanks Saumil
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