Problem related to Reset Circuit

Richa Deshpande

Other Parts Discussed in Thread: TMS320F28027

Hello,

We are working on TMS320F28027. We are facing problem with the reset circuitry.

It works fine maximum times but suddenly the controller gets reset. We are implemeting one testing procedure through which we have confirmed that the problem is related to the reset circuit.

The frequency of problem occurrence is undefined. Some times it comes every 5 to 10 mins and sometimes it takes months to generate the same.

Please guide us if possible.

Thanks and Regards,

Richa

over 13 years ago

0 Jayant Deshpande over 13 years ago

Expert 1495 points

Richa,

Have you checked the power circuit for BOR conditions ?

http://www.ti.com/lit/er/sprz292i/sprz292i.pdf

Also, please see extract from http://www.ti.com/lit/ds/symlink/tms320f28027.pdf about XRS pin:

If need be, an external circuitry may also drive this pin to assert a device reset. In this case, it is recommended that this pin be driven by an open-drain device. An R-C circuit must be connected to this pin for noise immunity reasons.

Hope this helps..

Regards,

JayantD

0 Richa Deshpande over 13 years ago in reply to Jayant Deshpande

Intellectual 505 points

Hi Jayant,

Thank you very much for your replies.

From Pin No.3, I have connected one 2.2KOhm Resistor to +3.3V and 1uF Electrolytic capacitor to common.

Is this a correct way to add RC to XRS Pin?

Also I am not getting the file and Register to set BORENZ bit in the BORCFG.

Waiting for your reply.

Thanks and Regards,

Richa

0 Jayant Deshpande over 13 years ago in reply to Richa Deshpande

Expert 1495 points

Hi Richa,

Sorry for my late response.. hope the problem has been solved by now!

It is a good practice to use higher values of R and smaller values of C.. saves space, and importantly, draws less inrush current.

Regards,

JayantD

0 Manoj Santha Mohan over 13 years ago in reply to Jayant Deshpande

TI__Guru 55700 points

Richa,

Jayant is absolutely right. I would also suspect a BOR event here. You seem to have a 2.2K pull up resistor. Even though I believe this should fine, it is still a very weak pull up. I would recommend 1K resistor.

I would also recommend you to check your voltage levels on VDDIO and VDD during operating conditions? Please hook up a scope and check the noise characteristics on both these pins. This should provide you some clues to proceed further with the debug.

Regards,

Manoj

0 Richa Deshpande over 13 years ago in reply to Manoj Santha Mohan

Intellectual 505 points

Hey Jayant and Manoj,

Thank you. Thank you very much for your suggestions.

The problem is resolved.

Best Regards,

Richa

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Problem related to Reset Circuit