Tool/software:
Hello,
I got the problem that the charge FET is always turned off. Therefore, my protection circuit does only allow discharging but no charging.
Above you can see my current design. I can't find the problem with the current circuit. The output voltage seems to be right, but the CRG FET is always turned off.
What could be the problem?
Best,
Andy
Hi Alexis,
thanks for the suggestion which really helped.
I narrowed it down to either overtemperature/ undertemperature or overvoltage protection kicking in. After some pointless searching I found that I used the wrong chip. Instead of the BQ7791500 I used the BQ7791506 version which has a lower OV threshold. A really stupid mistake which cost me a lot of time. I always thought there is just one single version.
I know the data sheet of the BQ77915 is kind of generic and probably covers a whole family of chips. But in the datasheet says that you are supposed to PROGRAM the OV (eeprom or resistor network). Then nothing follows without mentioning that you DONT actually program the chip but select one of the different versions which are mentionind in **Table 6-1** somewhere down hidden in the end of the datasheet. There is no reference at all to table 6-1 in the text.
I really recommend improving the datasheet (reference table 6-1) to help developers find the chip they really need and explain the content of the table in detail. Or I'm just stupid and nobody else encountered the problem. That might also be the case. At least ChatGPT is as stupid as me and insisted on rogramming the chip. That finally made me suspicious and helped me to find the error.
Best,
Andy
