I had a customer send me the following question that I need help with:
I am looking at using TI’s bq20z90/bq29330 chipset as a battery management/charging solution in my design and have a question regarding the PACK signal on the bq29330. The EVM user guide says I need to have a voltage higher than Vstartup on the PACK pin to enable the device to start. In the reference and EVM schematics PACK is connected to the downstream side of the discharging FETs which are turned off. How do I get a positive voltage on PACK?
There is a connector connection labeled as PACK+ on the bq20z90 EVM. Apply Vstartup voltage to that connector pin.
I think there is a miscommunication here. I know Vstartup must be applied to the PACK+ when using the bq20z90/bq29330 chipset. The question I want you to answer is, "When the bq20z90/bq29330 chipset is used as a battery management solution what is the source of Vstartup that gets applied to the PACK+ pin? Based on you existing answer it would lead me to believe the bq20z90/bq29330 requires a separate battery just to provide Vstartup to the PACK+ pin!
In the field, the power source for PACK+ is the charger.
When the battery cells are connected to the pcb the first time (during assembly in manufacturer factory), user can use a charger to just start the system. The device is on and there is no need to have a power source on PACK+. You will need to connect to the charger again if you want to start the device from a shutdown command, or if the battery voltage is below termination voltage (in that case, you will need a charger to charge your battery anyway).
That makes more sense now...Thanks
I am using bq20z90 EVM with bq29330. I have listed out the observations i found below:
1) I have connected 4 cells to 1N,1P,2P,3P and 4P respectively. I have no VCC at this point,
2) I gave 14v to PACK+ , now i get 2.5v in VCC; Even when i switch the PACK+ voltage off, i get the VCC voltage.
3) i use EV2300 for connecting SMBus of bq20z90 with PC. I have installed the software and drivers also, and my system recognizes TXbqxx river when i plug the usb cable.
PROBLEM : When starting the software, it gives either of the following error message.
1) Communication Error = No acknowledgement VB_T2H_NACK.
2)Communication Error = VB_COMMUNICATION_TIMEOUT.
I don't understand, what is going on ?
Please help me out !!!!
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