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Battery Management - Gas Gauge Forum
BQ77910A Default register values
I wanted to use bq77910a to balance a series of 10 Li -ion cells and use Single Power Path, with no FETs in DSG an CHG. I can rise the voltage at the CHG_DET above 0.5V while charging and cell balance should be done only while Charging. I wanted to use the IC with the default values in all the registers (No programming of the registers). Is it possible to do that, if not I would like to know the default values of all the registers so that I can get the Under voltage and Over voltage thresholds etc.
It should be able to do that. When not using the FET controls, CHG and DSG can be left open. CPCKN should be connected to VSS, DPCKN can also be connected to VSS.
Default register values are below in hex. The configuration is for 10 cells, 2.6V UV, 4.225V OV. Register 0x0A is the balance configuration, the threshold is 3.6V with operation based on CHGST with an 8 hour timeout. From the datasheet you can see that it will balance one cell at a time and will balance while enabled adjusting each high cell in turn. If you bring the cells to OV, balance will stop while OV is evaluated, then will continue.
Thank you very much for your reply. It definitely helps me a lot . I need a suggestion from you in finding a right charger for 10 cells connected in series. Can I use the same IC for charging also using a FET in the charging path and applying a constant voltage approximately equal to 10*4.2 = 42. Or the IC is intended to protect the battery from Over voltage and balances the cells while charging.
As you indicate, the bq77910A is a battery protector IC which related to charge will monitor the cell voltages and flag or open a FET to stop charge if a cell goes over voltage or other specific conditions occur.
A charger circuit will likely need to provide a regulated voltage for charging your 10 cells at the pack level (sum of cells) at a limited current, possibly adjust the current based on voltage and temperature. Depending on the power supply it may need to raise or lower the voltage for charging. You may also want or need some timer function or comparator function to stop charge based on a timeout or taper to a low current. For lower voltages you may find many of these functions in an IC, for higher voltages such as 10 cells, you may have to assemble more of it. The battery charger forum may have suggestions.
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