Article ID: 000080292 Content Type: Troubleshooting Last Reviewed: 09/11/2012

Can I pull up the JTAG configuration pins (TDI, TDO, TMS) of Cyclone III or Cyclone IV devices to VCCIO of 2.5V and above?

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Description

In Cyclone® III and Cyclone IV devices, the JTAG configuration pins (TCK, TDI, TDO, TMS) do not have internal PCI clamping diodes to prevent voltage overshoot when using VCCIO of 2.5V and above. Therefore to prevent damage at these configuration pins, you must not pull up the JTAG configuration pins to VCCIO above 2.5V.  Note that TCK should be pulled to ground.

 

For VCCIO of 2.5V and above, the JTAG configuration pins must be pulled up to VCCA. For VCCIO below 2.5V, you can pull up the JTAG configuration pins to VCCIO.

 

For detail information, refer to Configuration, Design Security, and Remote System Upgrades in Cyclone III Devices (PDF) or Configuration and Remote System Upgrades in Cyclone IV Devices (PDF). 

Related Products

This article applies to 2 products

Cyclone® III FPGAs
Cyclone® IV FPGAs

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