Hello I have to pilot a CMOS input 5V chip device with a 7474 flip flop with the lowest possible delay to minimize clock jitter. Signal is about 11.3 Mhz
I have two options:
1) 74HC74 (CMOS compatible) with maximum speed of about 30MHz
2) 74AS74 with a pull-up resistor with theoretical maximum speed of about 100MHz
I would use 74AS74 because this should have one third of propagation delay vs 74HC74 (hence one third of clock jitter probability, I suppose), but I would need a pull-up resistor to reach CMOS input voltage levels.
I was thinking of about 1K ohm of pull-up from the 74AS TTL output to the positive 5V rail, giving a safe 5mA load.
1) which is the lowest safer pull-up resistor for a 74AS piloting a CMOS device? Websites recommends from 10K to 2.2K from TTL to CMOS. I would use 1Kohm. Is it 470ohm still safe and better?
2) 74HC74 run at 30Mhz, 74AS74 run at 100Mhz. But which is the maximum speed (or propagation delay) of a 74AS74 with a pull-up resistor? Does the pull-up resistor jeopardise the 74AS speed advantages vs 74HC?
3) at the end: to minimise jitter driving a CMOS is correct that any 74AS with pull-up resistor is better of any 74HC device?
PS: don't want to use 74AC or other logic families. Question is only about 74AS vs 74HC.