SN74AVCH20T245: Is it possible to have a different direction for half of the ports of the device?

Stephane Mouton

Part Number: SN74AVCH20T245
Other Parts Discussed in Thread: SN74AVC20T245

Hello,

I'm working on a design where I need to interface a 1.8V powered microcontroller to several peripherals (mostly transceivers) that are 3.3V powered.

I have a total of 10 inputs and 10 outputs to shift between the two voltage domains.

When looking at the logic diagram of the SN74AVCH20T245 datasheet, it looks like the device can operate half of its ports independently. Although, since it's not crystal clear, I need a confirmation from you guys.

The way I intent to integrate the device on the design is as follow :

- VCCA = 1.8V, VCCB = 3.3V

- 1DIR = GND, 1OE = GND (in order to have 1Ax/1Bx ports direction set to : B data to A bus)

- 2DIR = 1.8V, 2OE = GND (in order to have 2Ax/2Bx ports direction set to : A data to B bus)

Is this mode of operation correct ?

Thanks in advance for your help !

Stéphane

over 5 years ago

0 ShreyasRao over 5 years ago

TI__Guru 57370 points

Stephane,

Yes, the 2 direction pins in the device are independently controlling 10 IO ports each and hence you can have 10 channels from A to B, while the other 10 channels can go from B to A or vice-versa.

Do you know if you need the bushold feature or would you prefer to use SN74AVC20T245?

What package are you considering?

0 Stephane Mouton over 5 years ago in reply to ShreyasRao

Prodigy 90 points

Thanks for the quick answer !
The bus hold is indeed needed for my application. I'm considering the BGA54 package.

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SN74AVCH20T245: Is it possible to have a different direction for half of the ports of the device?