• TI thinks resolved

PCA9306: VREF1=1.8V, VREF2=3.3V, pull-up resistance 2.0kohm, VOL=0.2*1.8=0.36V

Part Number: PCA9306

Hi Sirs,

We have use PCA9306.

If our VREF1=1.8V, VREF2=3.3V, pull-up resistance 2.0kohm, VOL=0.2*1.8=0.36V. right??

Actually our master side VIL=0.3VDD(1.8V)=0.54V.

We worries these value are too close.

So could you help double confirm have any risk on our design?




  • Hi Shu-Cheng,

    The VOL levels will actually depend on the pull-down strength of the I2C driver used. The pull-down resistance of the open-drain driver needs to be low enough to sink enough current from the pull-up resistances on both voltage rails (one directly, the other through the PCA9306 switch) to ensure that low enough low levels are achieved. Lower levels can typically be obtained by using higher pull-up resistance values, although this trades off bus speed (since higher resistances give slower rise times for equivalent capacitive loads).