Mark Kahrs wrote: Steven Hirsch wrote: Yes. The original is a SN74F623DW, which is very power hungry. It definitely does go flaky, and renders the system flaky to completely unusable. The replacement I recommend is the SN74ABT623DW, which is BiCMOS, though others have reported success with the 74FCT623M. SN74F623DW CD74FCT623M SN74ABT623DW ------------- -------------- --------------- max high level A port current -3 uA @ 2.4V -15 uA @ 2.4V -32 uA @ 2.0V max high level B port current -15 uA @ 2.0V -15 uA @ 2.4V -32 uA @ 2.0V max low level A port current 24 mA @ 0.5V 64 mA @ 0.55V 64 mA @ 0.55V max low level B port current 64 mA @ 0.55V 64 mA @ 0.55V 64 mA @ 0.55V max quiescent current (Iccz) 130 mA 1.6 mA 0.25 mA max tPLH, A to B 6.5 ns 7.0 ns 4.6 ns max tPHL, A to B 7.5 ns 7.0 ns 4.6 ns max tPLH, B to A 6.5 ns 7.0 ns 4.6 ns max tPHL, B to A 7.5 ns 7.0 ns 4.6 ns max tPZH, /OEBA to A 12.0 ns 9.5 ns 7.5 ns max tPZL, /OEBA to A 10.0 ns 9.5 ns 7.5 ns max tPHZ, /OEBA to A 7.5 ns 7.5 ns 7.5 ns max tPLZ, /OEBA to A 7.0 ns 7.5 ns 7.5 ns max tPZH, OEAB to B 11.5 ns 9.5 ns 7.5 ns max tPZL, OEAB to B 9.5 ns 9.5 ns 7.5 ns max tPHZ, OEAB to B 10.0 ns 7.5 ns 7.5 ns max tPLZ, OEAB to B 10.0 ns 7.5 ns 7.5 ns For port current, high magnitudes are better. For quiescent current and propagation delays, lower values are better. Note that the CD74FCT623M has slightly slower max tPLH time than the original SN74F623DW. Probably not a problem, but I prefer the SN74ABT623DW for that reason.