SN74GTL1655: Output Ringing Issue

Luke Sun

Part Number: SN74GTL1655

Hi team,

My customer met an output ringing issue when using SN74GTL1655. Below is the test data.

When input (BLue) is slowly ramping in the slew rate of ~2.3V/ms, the output (green) will generate a pulse rather than a simple step.

Could you give any advice how to avoide such issues?

1. Is there any input slew rate requirement of that chip?

2. Is there any way to avoid the ringing in current slow slew rate input?

Thank you!

over 5 years ago

0 Karan Kotadia over 5 years ago

TI__Genius 16725 points

Hello Luke,

It is interesting to see that pulse occur. If it were a slow input related issue you would see oscillations and maybe 50-80 pulses. The single pulse that occurs might be related to the device operation. Can you also give a scope shot with the clock to see whether the clock is causing that bit to pulse?

Thanks!
-Karan

0 Luke Sun over 5 years ago in reply to Karan Kotadia

TI__Intellectual 1830 points

Hi Karan,

Here's the schematics.

The CLK is tied to 3.3V. Could you check is there any problem?

Many thanks for your reply

0 Karan Kotadia over 5 years ago in reply to Luke Sun

TI__Genius 16725 points

Hi Luke,

I looked at your schematic and I didn't see anything wrong with it. I am not exactly sure why this is happening but can you try to increase the input rise time? If that clears up the pulse then we know that the slew rate is really slow and is causing the problem. The device's minimum input rise time was not spec'd so I don't have any data I can provide for that.

Thanks!
-Karan

0 Karan Kotadia over 5 years ago in reply to Karan Kotadia

TI__Genius 16725 points

Hello Luke,

Any updates? Have you figured out a solution or should I close this thread?

Thanks!
-Karan

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SN74GTL1655: Output Ringing Issue