Another electronics question

[Trevor Law]

So I need to help out on another school project in my group and I got these breakout boards w/ integrated level shifters for 3.3V->5V.  But the micro my team member is bringing over is actually 3.3V.  I want to use these boards, since they have nice sockets for the XBees, but need to bypass the level shifting and regulation functions.  From the schematic (attached), it seems like I can just connect both the 3.3V and 5V lines on the board and everything will be cool.  I looked at how the level shifting works in this app note:

http://ics.nxp.com/support/documents/interface/pdf/an97055.pdf

Anyone see a problem?

[Jacob Christ]

Not enough information need to know Vgs max for fets, but my gut says .3 more on the gate is no problem.

I think you meant to sat that it runs at 3V and you want to run at 3.3V.

Also should be no problem running 5V at 3.3V if the XBee can run at 3.3V

Jacob
Jacob

--
You received this message because you are subscribed to the Google Groups "MAGLab" group.
To unsubscribe from this group and stop receiving emails from it, send an email to maglaborator...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.
 
 

[Trevor Law]

Well I thought about little more.  They are designed mainly for 3.3V to 5V bidirectional shifting so I'm sure 3.3V is fine (otherwise pull up on gate would do nothing).  I was concerned about the ability of the 5V side to pull the line low if it was in fact a 3.3V part on that side, but realized that is silly since 0V is 0V, doesn't matter if other side 5 or not.

Pretty ingenious use of body diode of mosfet those level shifters are.