Author Topic: Will a Cyclone 3 TQFP-144 pack return a JTAG device ID with no decoupling caps?  (Read 501 times)

0 Members and 1 Guest are viewing this topic.

Offline MarkMosesTopic starter

  • Newbie
  • Posts: 4
  • Country: us
Will a Cyclone 3 TQFP-144 pack return a JTAG device ID with no decoupling caps?

Trying to test if a part is genuine, if I just put the chip in a clamshell socket, and connect power and gnd over say 10 mil traces to test ponts with no ground plane.

Powering off a bench supply.

What are the chances I could pull a device ID?

Asking for a friend... ::)
 

Online ataradov

  • Super Contributor
  • ***
  • Posts: 11905
  • Country: us
    • Personal site
Very high chance that it will. But you still need to supply the core and PLL voltages and at least the bank with the JTAG pins. So, the setup is not as simple.
« Last Edit: January 04, 2023, 09:23:46 pm by ataradov »
Alex
 
The following users thanked this post: MarkMoses

Offline MarkMosesTopic starter

  • Newbie
  • Posts: 4
  • Country: us
Well it turns out adding Decoupling caps and fixing some horrific routing of power on the JTAG fixture board "my friend" was making allowed it to come out of POR, and we were able to read a JTAG device ID etc.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf