AR# 6981


CPLD XC9500/XL/XV - Which JTAG pins have internal pull-up resistors? Do any of the JTAG pins need external pull-up resistors?


Which boundary scan pins have pull-up resistors on them?


The XC9500/XL/XV families have internal pull-ups on TMS and TDI, as required by the IEEE 1149.1 Standard. 

The pull-ups are terminated to the voltage present on VCCIO.

The TCK pin and TDO pin (which is an output pin) do not have an internal pull-up in any of these families.

An external pull-up is not required on any of the JTAG pins.

However, Xilinx recommends that external pull-ups of 47k Ohm or smaller be applied externally on all JTAG input pins (TDI, TCK and TMS). 

This helps to avoid inadvertent activation of the Boundary Scan in these device families.

AR# 6981
日期 06/27/2014
状态 Active
Type 综合文章
器件 More Less
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