Other Parts Discussed in Thread: BQ27Z561
At customer production mobile, Occasionally, BQ27Z561 response NACK when master access 0x55 address(BQ27Z561 7bit I2C address). You can see below picture. SDA is high at the 9th SCL pulse. Then we add some I2C access retry. Sometimes, I2C back to normal after retry. (Below picture success for the 2nd try. )However, at seldom random case, BQ27Z561 still response NACK even after 5 times retry. What might cause this phenomenon?
This is mass production issue and hope to get your strong help.