TCA39306: Using the device for a switch during Vref1=Vref2 and Vref2 >= Vref1+0.7

Mitchell Spears

Part Number: TCA39306
Other Parts Discussed in Thread: PCA9306

Hi INT team,

I am designing with the PCA9306 or TCA39306 and I was curious about the switch/EN capabilities of the device.

In the datasheet it calls out the Switch Mode vs the Translation Mode, but I wanted to know if you could also use the enable with a GPIO to open and close the switch.

What I see in the other threads is to use an open drain GPIO connected at the VREF2 and EN pin.

See diagram (should be an open collector npn BJT):

Will this work in both cases?

I look forward to your feedback.

Thank you,

Mitchell

over 3 years ago

+1 BOBBY over 3 years ago

TI__Guru* 78461 points

Hi Mitchell,

It's perfectly fine to use an open drain design such as a npn BJT on the EN pin of the 9306/39306 device.

-Bobby

+1 Clemens Ladisch over 3 years ago

Guru 320780 points

When the EN and VREF2 pins are tied together and through the 200 kΩ resistor to the high-voltage supply, then EN must be controlled with an open-drain/open-collector signal. (That transistor should be an NPN, not a PNP.)

When the EN pin is not connected to VREF2 and the resistor, then it must be controlled with a push/pull GPIO. (And then the voltages at VREF1/2 do not matter, and you can leave them open.)

0 Mitchell Spears over 3 years ago in reply to Clemens Ladisch

Prodigy 20 points

Understood! I had the wrong BJT symbol in visio :) thank you both for your help!

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TCA39306: Using the device for a switch during Vref1=Vref2 and Vref2 >= Vref1+0.7