I'm building an embedded controller that uses the Dallas 89C420 ultra high speed micro with an external 32K SRAM. There's no external program memory - I'm using the internal flash for that.
Right now it works just fine at 15Mhz with a 74HC373 address latch and a 70ns SRAM, however I want to run in clock doubled mode at 30Mhz. For this I figure I'll need to use a 74F373 latch instead of the HC part.
The trouble is that it doesn't work, even at 15Mhz 1X (i.e. not doubled) with the 74F part. Running a little memory diagnostic that I wrote, I get random SRAM errors that _don't_ occur with the 74HC address latch.
Are there any circuit changes that need to be made when using the74F373 instead of the HC part? Am I going to need series damping resistors or pull up resistors on the F373s outputs?
There are lots of Dallas appnotes for the 320, 550 and 420 family that talk about replacing the 74HC latch with a 74F part, but I couldn't find one actual schematic where they did it! Thanks much, Bob Armstrong