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.

SN74LV221A: PULSE CUT SHORT, RETRIGGERS WHEN IT SHOULD NOT

Part Number: SN74LV221A
Other Parts Discussed in Thread: CD74HC221, CD74HCT221,

Number: CS0323764
Contact: JOHN LIGUORI
First name: JOHN
Last name: LIGUORI
Short description: PULSE CUT SHORT, RETRIGGERS WHEN IT SHOULD NOT
Email: jliguori@firecominc.com
Company: FIRECOM INC
Company phone:
Language: English
State: Open
Provide case details or comments:

Dear Representative,

I’m using the SN74LV221APWR, and found the output pulse sometimes is cut short and the device retriggers when it should not.

I found references to this problem on the internet here:

e2e.ti.com/.../836072
e2e.ti.com/.../920058

Questions:

• Is TI currently working on resolving this problem?
• When will devices be available that always have correct output pulse width and are truly non-retriggerable?
• Are there any alternate non-retriggerable devices available now that operate at 5v and similar speed?

Thanks,

JOHN LIGUORI

  • Hi John and welcome to the forums!

    I can't give details regarding internal projects, however I can say that we are definitely looking into the issue.

    The LV221 is the only device that's shown this problem. I would recommend to instead use the HC or HCT variant CD74HC221 or CD74HCT221.

  • Does the problem exist in all SN74LV221A packages?

     

    Is TI planning on offering the SN74LV221APWR device (TSSOP) in the future that has the correct output pulse width and are truly non-retriggerable?

     

    When are the SN74LV221APWR devices (TSSOP) expected to be available for purchase?

  • Hey John,

    We are still working on locating the failing mechanism so I won't be able to answer your questions as of now. This process will likely take a long period of time so if you need a similar device in the near future I recommend using the devices Emrys mentioned.