General Description:
Do CoolRunner XPLA3 or CoolRunner-II devices require weak pull-up resistors on the JTAG pins between daisy-chained parts?
No, this is not required, but it is recommended. The internal pull-ups present on TDI and TMS (as required by the IEEE 1149.1 specification) can be as weak as 100k Ohm. As a result, it can be beneficial to apply external pull-ups to the JTAG pins to prevent noise from accidentally toggling the JTAG pins.
For XPLA3, the pull-ups are to VCCINT.
For CoolRunner-II, the pull-ups are to VCCAUX.
For more information, see (Xilinx Answer 11433).
AR# 7695 | |
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日期 | 12/15/2012 |
状态 | Active |
Type | 综合文章 |