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CD74HCT40105: EXPANSION, 8-BITS WIDE BY 16 N-BITS LONG USING.

Part Number: CD74HCT40105

Dear, support team.

Our customer has a question about EXPANSION, 8-BITS WIDE BY 16 N-BITS LONG USING.

Is the direction of the arrow of MASTER RESET "MR" on page 12 of the data sheet reversed?
I think MR is an input.

For note 6 on page 13 of the data sheet, is it the section from the first rise of SI to the rise of DOR?
Also, is the SO signal invalid during this period?

For note 7 on page 13 of the data sheet, is it the section from the first fall of SO to the rise of DIR?
Also, is the SI signal invalid during this period?

Is it possible to write less than 16Word (for example, put one in and take out one)?
https://www.ti.com/jp/lit/gpn/cd74hc40105

Best Regards,
Hiroaki Yuyama

  • Hi Hiroaki,

    Is the direction of the arrow of MASTER RESET "MR" on page 12 of the data sheet reversed?

    Yes the direction is reversed, the Master Reset MR is an input. 

    For note 6 on page 13 of the data sheet, is it the section from the first rise of SI to the rise of DOR?

    Yes

    Also, is the SO signal invalid during this period?

    When the FIFO is empty, DOR will remain LOW. The shift out signal will be invalid until a “1” marker ripples down to the last control register and DOR goes HIGH

    For note 7 on page 13 of the data sheet, is it the section from the first fall of SO to the rise of DIR?

    Yes

    Also, is the SI signal invalid during this period?

    The DIR flag will remain low when all 16-word locations are filled with valid data, so the shift in signal is invalid until the DIR flag goes high. 

    Is it possible to write less than 16Word (for example, put one in and take out one)?

    This device was not designed for this. 

    Regards,

    Sebastian 

  • Hi,Sebastian-san
    Thank you for your reply.

    I was able to clear the customer's question in the datasheet.
    The customer is designing to replace the SN74LS224AN with the CD74HCT40105.

    Best Regards,
    Hiroaki Yuyama