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SN74AHC123A: Need to found same function replace 74HC123

Rock Shao
Expert 2860 points
Part Number: SN74AHC123A
Other Parts Discussed in Thread: CD74HCT123, , CD74HC123

Hi, Teams,

Please help to double TI has the same as the 74HC123, and I have checked the TI family,

tw = K * RT * CT; need K=0.45 and tw<5ns.

CD74HCT123:
K=0.45 but tw=17~100ns

SN74AHC123A
K=1 needs to modify RC, tw=5ns

74HC_HCT123.pdf

  • 0
    Guru 262120 points

    As shown in the linked 74HC123 datasheet, the minimum pulse width that is guaranteed to be available is 17 ns. Neither the CD74HC123 nor the SN74AHC123 datasheets specify a minimum value, but figure 5 of the SN74AHC123 datasheet shows that 5 ns is outside what this device is typically used for.

    AHC family devices switch faster than HC ones, so 5 ns might be possible. But the capacitor reuqired for that is so small that the parasitic capcitances of the device and the traces become significant, so you have to calibrate the values to your board, and there is no guarantee.