TSC2007: Power off ramp doesn't meet the criteria but VDD off-time can meet.

Evan Liu

Part Number: TSC2007

Hi TI Expert,

I have a question about the VDD off-ramp requirement.

For some reason, we can meet the VDD off time and power on-ramp requirement, but we CANNOT meet VDD off-ramp.

Can we increase the VDD off time(maybe 2s or 3s) and skip the VDD off-ramp? The idea is to make sure that the POR capacitor is fully discharged enough before power up again.

From the following link, Page 2, it only says that "it is recommended to have a specified VDD off-ramp".

TI App. Note: http://www.ti.com/lit/an/sbaa161/sbaa161.pdf

From my perspective, it implies that maybe we don't need to meet VDD off-ramp in some cases. Please help to check on it.

Thank you so much.

over 3 years ago

0 Sanjay Dixit over 3 years ago

TI__Mastermind 23030 points

I think that if the off time is set long enough, it is equivalent to a recycle of power and this can reset any lockup condition.

However I do not have any suggested timing i can suggest. This can be determined emperically by forcefully generating a lockup and measuring off times needed to remove lockup.

0 Evan Liu over 3 years ago in reply to Sanjay Dixit

Prodigy 10 points

Hi Sanjay Dixit,

Yes, this is what I want to confirm.
However, do you have any ideas that can make a lock-up maunally?

Thank you so much.

0 Sanjay Dixit over 3 years ago in reply to Evan Liu

TI__Mastermind 23030 points

You could try connecting a DC Power supply to power input and increase it slowly to full value. They may generate a lockout.

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TSC2007: Power off ramp doesn't meet the criteria but VDD off-time can meet.