Programmable Devices
CPLDs, FPGAs, SoC FPGAs, Configuration, and Transceivers
Announcements
All support for Intel NUC 7 - 13 systems has transitioned to ASUS. Read latest update.
20559 Discussions

Routing a 5V signal through a 3,3V Cpld. Is the output 5V or 3,3V?

Altera_Forum
Honored Contributor II
1,099 Views

Hi, I'm using an old Altera Cpld in a project, a Max 7000 series, which needs a 3,3V Vcc but the IOs are 5V compatible. 

 

So, if I put a 5V input IO and route it to other output IO, this output will be 3,3V or 5V? By routing I mean a direct connection in my vhdl code. 

 

I have some 5V inputs, and I want to put a 3,3V chip behind the Cpld, so I'm expecting that the output would be 3,3V, otherwise I can't use this approach. 

 

Sorry if it's a newbie question.  

 

Thanks...
0 Kudos
2 Replies
Altera_Forum
Honored Contributor II
334 Views

As the CPLD is powered by 3.3V, the outputs cannot be higher voltage than these 3.3V ;-)

0 Kudos
Altera_Forum
Honored Contributor II
334 Views

 

--- Quote Start ---  

Hi, I'm using an old Altera Cpld in a project, a Max 7000 series, which needs a 3,3V Vcc but the IOs are 5V compatible. 

 

So, if I put a 5V input IO and route it to other output IO, this output will be 3,3V or 5V? By routing I mean a direct connection in my vhdl code. 

 

I have some 5V inputs, and I want to put a 3,3V chip behind the Cpld, so I'm expecting that the output would be 3,3V, otherwise I can't use this approach. 

 

Sorry if it's a newbie question.  

 

Thanks... 

--- Quote End ---  

 

 

You may also check the device datasheet for further details on the expected output voltage. However, as Calhermann mentioin, if the chip is powered by max 3.3V, the max output IO voltage should be capped at 3.3V. For the input, there might be some internal clamping which allow it to interface with 5V. 

 

Best Regards, 

bfkstimchan 

(This message was posted on behalf of Intel Corporation)
0 Kudos
Reply