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SDA pull down in PF4210 & PF0100 

Question asked by wswong Employee on Jul 31, 2019
Latest reply on Aug 12, 2019 by Jinyu Zhang

Dear Team,


Customer found SDA pin of PMIC PF4210 keep in low status when VDDIO is supplied (VDDIO =3.3V) but without VIN (VIN = 0V). There is no such issue in SCL pin and it can pull up with VDDIO only. Both SCL and SDA pin are pull up to VDDIO with 4.7K resistors. If VIN is supplied (3.3V), the SDA status can pull up to VDDIO level and that status can keep  even after VIN is turn off. Same result can be found in both PF4210 EVK and customer board.    


That issue affect other slave devices on the same I2C bus cannot be communicate if supply does not provide to PMIC VIN.   


Similar symptom can also be measured in PF0100 EVB. Is that symptom normal?  Does VIN must power for the I2C interface/SDA level stable setup to open-drain pull up?


For the application that other slave devices need share the I2C interface/bus with the PMIC (but no need PMIC to work), customer try workaround by power up VIN once, then power it down and only keep VDDIO supply. Is that workaround reliable and What is the suitable workaround for that issue case?  


Can we share the internal block diagram of the I2C interface of PMIC to explain that symptom.   


Thanks and Best Regards,