PCA9306: 3.3V to 3.3V Isolation

Inderjit Bains

Expert 2745 points

Part Number: PCA9306
Other Parts Discussed in Thread: SN74LVC2G66

Can VREF1 = VREF2 = 3.3V? Just to use the PCA9306 to isolate one I2C bus from another.

Related: Can VREF2 = 0V when VREF1 = 3.3V?

0 Clemens Ladisch over 1 year ago

Guru 243920 points

This device is a passive switch. It isolates the buses only when EN is pulled to GND.

If you want to disconnect two buses from each other, use a simple switch like the SN74LVC2G66.

0 Inderjit Bains over 1 year ago in reply to Clemens Ladisch

Expert 2745 points

The part is designed in to a prototype. Will it work when VREF1=VREF2=3.3V?

0 Clemens Ladisch over 1 year ago in reply to Inderjit Bains

Guru 243920 points

Yes, but you could replace it with two wires.

When VREF1 = 0 V, a current will leak from VREF2 to VREF1. But when VREF2 = 0 V, EN also is 0 V, and the I/Os are disconnected.

0 Inderjit Bains over 1 year ago

Expert 2745 points

We need to turn VREF2 and EN off during sleep, otherwise we wouldn't need to isolate the I2C buses.

0 Clemens Ladisch over 1 year ago in reply to Inderjit Bains

Guru 243920 points

Yes, that would work.

0 Chris Ayoub over 1 year ago in reply to Clemens Ladisch

Inderjit,

Clemens is correct. If your supplies are equal to each other you can use the device in a switch configuration:

Best,

Chris

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