AR# 508: XC4000/XC5200: PROGRAM pin designed to ignore glitches <50nS)
XC4000/XC5200: PROGRAM pin designed to ignore glitches <50nS)
Keywords: PROG pin, configuration, XC4000, XC5200
The Program pin designed to ignore glitches less than 50ns. Glitches on the PROGRAM pin of the XC4000 can potentially initiate an unwanted reconfiguration. To help avoid this, the chips are designed to ignore pulses which are shorter than 50ns. Note, however, that this is NOT a tested parameter.
NOTE: the minimum pulse width to guarantee a reconfiguration is 300ns.
If operating in a noisy environment where glitches of roughly 50ns occur, the user can add external circuitry for additional RC filtering on the input of Program.