PCA9306: Can Switch Configuration be used with VCC1=3.07V and VCC2=3.3V?

1. This is no problem; the switch configuration works with any voltage difference less than 0.7 V.
2. When EN is above the FET's threshold voltage, which is about 0.7 V, it allows low-level signals to pass.

If you want just a switch, better use a real switch like the SN74LVC2G66.

Hi Kazuya,

Kazuya Nakai59 said:

Q1.
They want to use Switch Configuration of Figure 8-5 in the device datasheet with VCC=3.07V and VCC2=3.3V.
In this condition, Is there any problem?

This shouldn't be a problem. I assume EN pin voltage is 3.3V. This will set the gate voltage high enough of the internal passFET to keep both sides separated when pulled logic high. 

Kazuya Nakai59 said:

Q2.
If the usage is no problem, how much is EN pin threshold voltage to turn on/off?

I agree with Clemens here. When EN pin voltage is above the passFET's threshold voltage (~0.7V), it allows low-level signals to pass through the device. For example, if you have I2C signal of 3.07V while EN voltage is 3.3V, you would expect the device to separate side 1 and side 2. When the I2C signals begin to pull low on side 1, you can expect side 1 and side 2 signals to follow each other when side 1 reaches a voltage of 3.07 - 0.7 = ~2.37V. 

If you are looking for a specific EN voltage threshold that will turn off the device completely, then you would want to go with something like Clemens suggested with the SN74LVC2G66. 

Regards,

Tyler