• State Answer Suggested
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 19 subscribers
  • Views 1075 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SN74AHC595: SN74AHC595PW application question

Shu-Cheng LIN
Guru 11785 points
Part Number: SN74AHC595

Hi Sirs,

Sorry to bother you.

We have use SN74AHC595 to replace NXP 74AHC595.

Schematic as below

The SH-PoE’s LED is random display during manual reset.

MR=SN74AHC595 SRCLR

But can normal display after manual reset.

Our understand is register is cleared.

But actually there have random output.

We have disconnect output load but still have same phenomenon

Could you help to explain this issue?

Thanks!!

 

  • 0
    Guru 276270 points

    The datasheet says:

    The SN74AHC595 device contains an 8-bit serial-in, parallel-out shift register that feeds an 8-bit D-type storage register.

    So "shift register is cleared" means that only the shift register is cleared; you still have to run a clock to make it visible at the outputs (as shown in figure 1).

    Nexperia's 74AHC595 behaves in the same way: