I am designing a circuit which will buffer 3.3V input from Raspberry pi using 74ABT244D,623 and there will be 4 output chains on the PCB. Each chain will be connected through FRC to a second PCB with an immediate buffer of 74AHC245. But one data line will be shorted into 4 to get 4 outputs.

So from 1 single output of 74ABT244D,623, can it drive 4 inputs to 4 74AHC245 each (16 total) ?

Reference image :- enter image description here

  • \$\begingroup\$ The answer might depend on what FRC is. \$\endgroup\$ – user_1818839 Oct 18 '20 at 21:50

What does your datasheet say?

-32mA (hi) 64 mA (Lo) drive

+/-1 uA load + 10pf (Ic=C dV/dt) per transition

What is load capacitance? And frequency? To determine Zc

So far so good, what f ? low? No problem

  • make sure to use decoupling cap on IC’s. ~0.01 uF typ.
  • \$\begingroup\$ I don't understand this - So far so good, what f ? low? No problem \$\endgroup\$ – Sap Oct 19 '20 at 13:04
  • \$\begingroup\$ Sorry but can you explain again \$\endgroup\$ – Sap Oct 19 '20 at 13:04
  • \$\begingroup\$ @Sap what is your frequency, at DC it can drive 32,000 gates"? I mean on this output \$\endgroup\$ – Tony Stewart EE75 Oct 19 '20 at 13:05
  • \$\begingroup\$ 32 Mhz maximum. 19.2 Mhz typical \$\endgroup\$ – Sap Oct 19 '20 at 13:06
  • \$\begingroup\$ Not uC, I meant on this bus, CMOS takes very little current on input, you are OK there (so far, OK, what is your load? mA or type or, \$\endgroup\$ – Tony Stewart EE75 Oct 19 '20 at 13:11

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