74LVC8T245 octal buffer / level translator


#1

The last in a series of chips that are useful for level translation between 1.6V and 5V (and the other way) systems. This one consists of 8 tristate output buffers in a 24 pin SMD (only) package. Unlike the rest in this series (which are all unidirectional) this one is bidirectional and can translate any voltage from 1.8 to 5V to any other voltage in that range. This part is also a bit odd in that because this chip is SMD only (the others are available in DIP) the breadboard here is actually a module (available on ebay, search for “74LVC8T245” and you will find them) while PCB view is an SMD footprint making the same part work for both the module and the chip. Since this chip is designed specifically for level translation, it should probably be your first choice for level translation. This part is slightly odd in that there are more pins in breadboard view than either schematic or pcb, but it none the less appears to work fine (the extra pins are power and ground and are bussed together). Note that the control inputs (~OE and DIR) are at the logic levels of the VCCA power source (which will usually be the lower voltage) so you may in fact need level translation on the control inputs if you need to drive them from the other domain. Note also that I cheated slightly and aligned the control wires on .1 boundaries (the module has them offset by .05in) and set the control module pins to female so that they won’t short if connected to the breadboard.

74LVC8T245.fzpz (21.9 KB)

As requested previously, a copy of the bb image so you can see what the module looks like without downloading the part.

Peter


Shift level converter wie kann ich den