Overshoot spec for OMAPL138 inputs

Rick Thaxter

Other Parts Discussed in Thread: OMAPL138

We have a signal driving pin C19 of OMAPL138 which overshoots/undershoots and violates the
absolute maximum voltage limits, but its duration is well within the time limit.

The question is this: can the device tolerate the excess voltages if the
duration of the excess is very short?

Vmax: 4.11V (abs max spec at 3.275V = 3.93V)

Vmin: -0.86V (abs max spec at 3.275V = 0.655V, symmetry assumed)

%time above spec: 1% (abs max spec = 20%)

over 9 years ago

0 Senthilkumar Srinivasan over 9 years ago

TI__Mastermind 43660 points

Hello Rick,

Welcome to the TI E2E forum. I hope you will find many good answers here and in the TI.com documents and in the TI Wiki Pages (for processor issues). Be sure to search those for helpful information and to browse for the questions others may have asked on similar topics (e2e.ti.com).

The overshoot/undershoot must be within the absolute maximum limits in terms of both voltage and duration. If you violate any one of the limit also would create functional issues. So i would suggest you to minimize the overshoot/undershoot within the limits.

Regards,
Senthil

0 Rick Thaxter over 9 years ago

Prodigy 50 points

Thanks for that. Does the +20% time start ticking when the signal crosses the DVDD threshold? And for undershoot: is the threshold at 0V?

0 Senthilkumar Srinivasan over 9 years ago in reply to Rick Thaxter

TI__Mastermind 43660 points

Hello Rick,

The +20% time start tickling when the signal crosses the maximum limit (DVDD + 0.3V) of the DVDD. The undershoot is the negative swing of the voltage less than DVDD - 0.3V and it is not at the threshold level of 0V.

You may find the below figure helpful to understand this.

Regards,

Senthil

0 Rick Thaxter over 9 years ago in reply to Senthilkumar Srinivasan

Prodigy 50 points

Thanks, Sethil. That answers the question.

Best regards

Rick

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Overshoot spec for OMAPL138 inputs