Hi, team,
It is an emergency issue. This problem occurs before customer pre-production. I may need to communicate with you via email later. In general, customer found that after repeatedly re-plugging the adapter (that is, VBUS repeatedly and quickly powered on/off, The battery remains connected during the entire process) many times, some registers value will change automatically, resulting in no charging.
The control registers changes as follows:
REG04 change from 0x22 to 0xd6. 0x22 is default value. The host MCU code does not actively configure this register.
REG05 change from 0x9D to 0x01. 0x9D is default value. The host MCU code does not actively configure this register.
REG06 change from 0x7D to 0x34. 0x7D is default value. The host MCU code does not actively configure this register. As EN_CHG bit set to 0, I think it is the reason for no charging.
The status register changes as follows:
REG0B change from 0x44 to 0x0
REG0C change from 0xd0 to 0x80. 0x80 seems to be strange value which means Power Good but VBUS Status is No input.
From above results, There are two questions that need your answer:
1. Why do the values of these control registers change automatically? Does our charger have this automatic change mechanism, especially for the EN_CHG bit?
2. How to understand the REF0C 0x80 value? Is it caused by an exception during replug?
I have two suspicions:
1. The adapter was unplugged during the power-on sequence self-test, causing an error. I do see this description in datasheet.“BQ25883 adapter re-pluin required restart device”
Customer did not do any restart operation recently. Does the restart operation here mean /CE to be pulled low again and EN_CHG to be reset?
2. I2C communication error when re-plugin, causing an error. Customer MCU configure operation will start quickly when VBUS is powered on. There may be conflicts between MCU configure and power-on sequence self-test. So far I2C waveforms have not captured any abnormal waveforms
