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SN74HCS595-Q1: Absolute Maximum Ratings of OE

TAKAHIRO HOJO
Prodigy 150 points
Part Number: SN74HCS595-Q1
Other Parts Discussed in Thread: SN74LV595A-Q1, SN74AHC595-Q1

Tool/software:

Hello!

What is the rated voltage of the OE pin when VCC is 0V?

Since OE is active low, I plan to pull it up to 5V with 10kΩ outside the IC.

Is it OK if the Absolute Maximum Ratings of IIK is satisfied when VCC is 0V?

     5V / 10kΩ = 0.5mA < 20mA

thank you.

  • 0
    Guru 267140 points

    A current of 0.5 mA might be enouch to charge the decoupling capacitor and to power up the device.

    Can't you pull up to VCC?

    There are devices without clamping diodes, e.g., SN74AHC595-Q1, SN74LV595A-Q1.

  • 0 in reply to Clemens Ladisch
    Prodigy 150 points

    Hello!

    I only want to know about rated voltage (or rated current) of the OE pin especially when VCC is 0V.

    I'm considering the following usage:

    ・OE pin is always pulled up to 5V with 10kΩ.

    ・In order o reduce current consumption, VCC pin  is controlled to either directly input 5V or not.

    thank you.

  • +1 in reply to TAKAHIRO HOJO
    TI__Genius 17240 points

    The pin will not be damaged, however what Clemens is saying is that you can power up the device through the pull-up on the OE pin, even when VCC is 0V. Thus we still recommend that the pull-up resistor connects the OE pin directly to VCC.