We are using the BQ24055 in our board design to charge a small 3.7V Lithium battery. The maximum current we allow is 220mA. The battery is charged via a standard USB, and we are compliant with USB protocol. Our product is a control board that powers an LED. When the product is shipped, the customer is provided a outlet switching power supply and a USB cord.
Recently, a customer returned our product where we discovered that the chip had got very hot, enough to slightly melt the plastic housing containing the circuit board.
What we know from the customer. They DID NOT use our power supply. We have requested that they provided us information on what they used.
QUESTION: knowing that there are many USB cables and associated power supplies, what could cause the chip to fail? Reverse voltage? Active USB pins that should have been deactivated? I am looking for ANY possible reason... This is the first time we have seen this issue.
Regards, Kurt
