• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 19 subscribers
  • Views 148 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.

SN74HC244: Package markings changed ?

Robert Hinchy
Prodigy 50 points
Part Number: SN74HC244

Tool/software:

Dear Sir/Madam,

We have the SN74HC244PW listed on one of our legacy products. This is used to drive 7 LEDs on our product. 

The SN74HC244PW is now obsolete so we changed over to the SN74HC244PWR which should be a drop-in replacement correct?

We ordered some SN74HC244PWR from digikey but found some odd behaviour where the LEDs remain stuck-on with the new SN74HC244PWR devices inserted. 

We have also noticed that the device markings have changed. See images below.

Can you confirm that the device markings have changed (hopefully we have not purchased counterfit products)?

Can you confrim that the performance charicteristics have not changed for the SN74HC244PW / SN74HC244PWR 

 

Old working device

New not working device

  • 0
    Guru 285080 points

    The "R" suffix indicates a large reel; this does not change the chips.

    There was a change to the marking style; this does not change the die.

    But there was also a change to the die. Newer devices have a shorter propagation delay and some hysteresis on the inputs. The guaranteed characteristics of the device have not changed, but it is possible that your circuit relies on some other characteristics. Please show the schematic, and an oscilloscope trace of an A/Y pin pair that does not switch correctly.