BQ25731: BQ25731 operation difficulties

We have the part in a design.  We would like to get it working.  We have established I2C comms to the IC using a SiLabs controller.  Are there I2C commands that are required to get the BQ25731 to start charging a 4 cell Li pack?  We have the Cell_BatPresz pin set to the correct voltage.  The rest of the circuit is the same as the circuit shown in the datasheet.  5V input on VBus does not startup the charging process.

Hi, Eric,

Try two things: 

1. Remove any load and startup again. 

2. Apply input voltage higher than 5V, such as 12V and try it agian. 

Let me know the results.

Regards,

Tiger

Hi Tiger,

Will the BQ25731 operate without the use of any I2C commands or status checks?

Thanks, Eric

Can you send me a list of the register bits that need to be set or cleared in order to get the boost switching started?  So code of any kind would be good, or at a minimum the order in which the registers must be written to enable the boost switching.  We are using the same topology and values as outlined in the datasheet.  There is a large order being planned for this application and there is a lot riding on getting this part working.