SN74LVC8T245DBR - 8-bit dual-supply bus transceiver

Mike Pascucci

Hi,

I am using one of the SN74LVC8T245DBR chips, and I want to be able to control the direction using a digital output line (at 3.3v).

I see in the data sheet that the direction pin is designed to be either GND or VCCA, but I want VCCA to be 5v, and direction to be 3.3v.

I see that VCCA (and therefore direction) can be as low as 1.65v, but is it okay to have them be at different levels?

Thanks,

Mike

0 Chris Cockrill over 14 years ago

You can not do this. The Vih of VCCA x 0.7 will not be met. You could use VCCA as the 3.3V side.

0 Mike Pascucci over 14 years ago in reply to Chris Cockrill

ok, thanks

0 Mike Pascucci over 14 years ago in reply to Mike Pascucci

Another question: I have a bypass cap on VCCA (0.1uF)... is a bypass cap recommended on VCCB as well? If so, is 0.1uF acceptable?

0 Chris Cockrill over 14 years ago in reply to Mike Pascucci

is recomended that you have a bypass capacitor on each Vcc pin as close to the pin as possible. 0.1uf is good.

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