PCA9306: ViL

Hi Kevin,

Since PCA9306 uses a pass FET architecture, ViL is not a discrete value referenced internally by the device such - as what might be seen in a digital input buffer. For this device, ViL is essentially Vref1. Whenever the voltage on side 1 or 2 decrease below this value, the device begins to conduct, allowing the LOW to pass through from either side. For voltages above Vref1, the conduction is blocked. This allows a higher voltage to pullup on side 2 without propagating to side 1.

A more in-depth explanation can be found here:
e2e.ti.com/.../809936

Let me know if you have any more questions regarding this device or how it may specifically fit into your application.

Regards,
Eric

Dear Eric,

Thanks for the input.

We have a IC PU6 that will outputs 0.6~0.85V I2C signal into PU4 but PU4 max ViL is only 0.4V.

Do you have any I2C buffer or repeater that can accept 0.85V(@3.3V supply) as logic low and out  a voltage below 0.4V as logic low?

BR

Kevin

Hi Kevin,

The TCA9800 family of buffers offers very low Vol on both sides. The low-level input voltages for these devices are 0.3xVcc which will allow communication with the PU6 device.

Selecting which device you use from this family will be dependent on the data-rate of your system. Since it appears that a SVO is present on the A side of PU6, I would recommend putting the current source side of the TCA980x facing PU4. Keep in mind you will not need to add pull-up resistors on the current source side of the device (as you would have done with the PCA9306).

Let me know if you have any other concerns.

Regards,
Eric

Dear Eric,

Thanks for the information.

Can both sides be used with 3.3V?
The bottom test conditions seem to be VI=0V, but when VI=0.85V (still below 0.3*VCC), is the VOL still able to meet the underlying specifications (max <0.26)?

BR

Kevin