data/text/DLP3/898425

BQ4050: LED Display, Auto Start of FETs, SMB Bus connection

Part Number: BQ4050 I have a custom board with BQ4050 and BQ25703a and an EV2400 for development purpose. So far everything works as expected but I do have some minor issues/questions: I have the /DISP pin shortened to GND. Is it still possible to drive the LEDs to indicate SOC? I plan for a battery that is NR, and the NR bit is set. However, for development purposes I can disconnect the battery over a connector to power the system off. Whenever I connect the battery to the system, the FETs won't turn on, I have to frist put in the power adapter and then the FETs turn on. Is there a way to turn on FETs automatically when BQ4050 detects a battery? Note: PRES is permanently connected to GND. I can read the BQ4050 registers with ESP32. However, after a couple of minutes I cannot read certain values (e.g. cell voltages) anymore, althought some value are still readable (e.g. SOC). Any ideas on this issue?

See my answers below. I have the /DISP pin shortened to GND. Is it still possible to drive the LEDs to indicate SOC? [Andy]No. As you see in the TRM, the bq4050 device has an LED display that shows various status information when a high-to-low transition of the DISP pin is detected. I plan for a battery that is NR, and the NR bit is set. However, for development purposes I can disconnect the battery over a connector to power the system off. Whenever I connect the battery to the system, the FETs won't turn on, I have to frist put in the power adapter and then the FETs turn on. Is there a way to turn on FETs automatically when BQ4050 detects a battery? Note: PRES is permanently connected to GND. [Andy] No. The gauge assumes it works in the NON-REMOVABLE mode since the NR bit has been set. I can read the BQ4050 registers with ESP32. However, after a couple of minutes I cannot read certain values (e.g. cell voltages) anymore, althought some value are still readable (e.g. SOC). Any ideas on this issue? [Andy]Try bqStudio and see if you can see the same problem.

Thank you. I would have another 2 question: When is a secondary cell voltage monitor (e.g. bq294502) necessary in addition to bq4050 and bq25703a? Is there any further reading available on this topic? It seems like bq28z610 would be a suitable replacement for my application, as it has a lower external component count and I only have a 2s config. Would this be an appropriate replacement? Are there any drawbacks (e.g. more effort to calibrate or set up)?

See my comments below. 1) See this thread <secret URL>/support/power-management/f/196/t/616636. 2) BQ4050 a CEDV based gauge while BQ28z610 is an Impedance Track gauge. Normally, bq28z610 is able to provide more accurate SoC prediction. In addition, bq28z610 needs a correct chemistry id to work properly and also a learning cycle needs to be done. Andy