SN74LS06: SN74LS06N Stays Low Output

Masa Katayama

Part Number: SN74LS06

Dear Sir,

My customer met an intermittent (once a year, 24hrs/day) fail that SN74LS06N output stays low when inputing 100kHz 50 to 90% duty square signal.

The circuit is as follows. Three parallel inverters drive OnSemi BD135B family power transistor thru 1kohm pull up resisto to 15Vdc. (changed 500ohm but not solved).

Power off-on toggle reset the fail and work after power on reset.

I am not sure it this is latch-up or this circuit have any potential issue.

May I get your advice if you have some idea to improve this kind of error?

Best regards,

Masa

over 6 years ago

0 Dylan Hubbard over 6 years ago

TI__Mastermind 44620 points

Hi Masa,

Could I get some scope shots of this issue happening and a scope shot of proper operation? It would be nice if the scope shots include the input, output, VCC, and GND on their own channels. This will assist us in debugging this issue. Also could get some info of the number of failing units vs the number of working units?

0 Masa Katayama over 6 years ago in reply to Dylan Hubbard

Intellectual 970 points

Hi Dylan,

thank you very much for your points.
The trouble happened at field and they recovered by power on reset without having a chance to scope.
I am asking the customer for scope shot at normal operation as well as N.

Best regards,
Masa

0 Dylan Hubbard over 6 years ago in reply to Masa Katayama

TI__Mastermind 44620 points

Hi Masa,

Thanks, those will be really helpful for me to debug the issue. So it seems this is just one system failing out in the field and not reoccurring issue among multiple systems. Could also could I get more of the schematic exposed so I can see if there is anything else connected that could be forcing that node low?

0 Masa Katayama over 6 years ago in reply to Dylan Hubbard

Intellectual 970 points

Hi Dylan,

Thank you very much for your support. Yes, I am investigating the multiple board or single board issue. I would like to send full schematic which is the customer propriety then I would like to send thru email. May I get your email address to my email address (katayama-m@macnica.co.jp)

best regards,
Masa

0 Dylan Hubbard over 6 years ago in reply to Masa Katayama

TI__Mastermind 44620 points

Masa,

Feel free to email it to me at d-hubbard@ti.com .

Logic

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SN74LS06: SN74LS06N Stays Low Output