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CD14538B and SN74LVC74A - the connection from Q to PRE

Dice-K
Mastermind 6330 points
Other Parts Discussed in Thread: SN74LVC74A, CD14538B

Hello,
I have a question about CD14538B and SN74LVC74A.

Can I connect the red line such as the circuit below?

SN74LVC74A   Recommended Operating Conditions

SN74LVC74A   Electrical Characteristics

The output transition rate of CD14538B is about 50ns/V.
200ns/(4.5V-0.5V)=50ns/V

The input transition rate of SN74LVC74A is 10ns/V.
Does this apply to PRE-terminal?
If it is correct, cannot I use this circuit?
The speed of transceiver is slow.
Or can I use it because the input capacitance of the PRE-terminal is not 50pF?

Regards,
Dice-K

  • 0
    TI__Guru 56100 points
    Hi Dice-K ,

    The input transition rate applies for PRE terminal since it is considered input . It is built not to tolerate slow inputs very well . It is generally not advisable to violate the recommended conditions of the part however if you consider the typical operation of CD14K it will have 25ns/V and with CMOS load not presenting 50pf you should be good . I do not anticipate any problems on the operation .
  • 0 in reply to ShreyasRao
    Mastermind 6330 points
    Hello Shreyas,
    Thank you for your reply.

    I understand that your answer means this circuit does not have any problems when the output load of CD14K is not large like 50pF.

    Best regards,
    Dice-K