SN74HC74: Performance Issue

David Hernandez

Part Number: SN74HC74

Tool/software:

Good morning,

We have been experiencing some performance issues with this component and We were wondering what could be the cause of it. We are attaching detailed information due that We saw that there's 2 components (same part number) with the same characteristics, but the performance is not the same. Hope that You can give Us some information that can help Us out to understand.

Analysis SN74HC74D.pdf

Best Regards

2 months ago

0 Malcolm Lyn 2 months ago

TI__Mastermind 26290 points

Hi David,

Could I see an actual schematic of the two parts and their connections, as well as a better picture of the input/output waveforms? Although I appreciate the detailed information, it's hard for me to determine anything from what you provided, and I am a little confused as to the 40V offset.

Best,

Malcolm

0 David Hernandez 1 month ago in reply to Malcolm Lyn

Prodigy 15 points

Hello, good day
Data sheet is the same for both components, as far as We read is that 74D is already an obsolete part, but still based on the data sheet they should perform equally.

0 Malcolm Lyn 1 month ago in reply to David Hernandez

TI__Mastermind 26290 points

David,

Could you upload the pdf for the schematic? Or just email it to me at m - lyn @ ti.com? I don't have access to the google drive.

Best,

Malcolm

0 David Hernandez 1 month ago in reply to Malcolm Lyn

Prodigy 15 points

File was sent by email

Thanks a lot

0 Malcolm Lyn 1 month ago in reply to David Hernandez

TI__Mastermind 26290 points

Hey David,

I was inquiring as to the schematic for your design, not the datasheet for the part.

I need two things to help you solve this issue:

The schematic for your design, to understand what is driving the various signals into the SN74HC74/how they are being driven
Higher resolution scope shots of the input clock, data, and the output waveforms. I am specifically interested in the rising edge slew rate of the input signals.

The DG4 part is on a newer process, and it's also possible that those parts simply have a higher drive strength as a result.

Best,

Malcolm

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SN74HC74: Performance Issue