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AM625: Regarding logic compatibility of Watchdog timer(TPS3431SDRBR) with AM625x

Premalatha Royappan

Intellectual 910 points

Part Number: AM625
Other Parts Discussed in Thread: TPS3431

Hi,

We are using watchdog timer(TPS3431SDRBR) with AM625x. While checking logic compatibility for WDI pin, we found for watchdog timer ViH(min) is 2.64V(0.8 × VDD).But VoHmin of AM625x is 2.4V. Please clarify if these 2 devices are compatible.

over 2 years ago

0 Kallikuppa Sreenivasa over 2 years ago

TI__Guru**** 175744 points

Hello Premalatha Royappan,

Thank you for the query.

VoHmin value of AM625x is load dependent.

Since you are looking at interfacing to the TPS3431SDRBR, someone from the supervisor team could help.

Let me internally reassign.

Regards,

Sreenivasa,

0 Premalatha Royappan over 2 years ago in reply to Kallikuppa Sreenivasa

Intellectual 910 points

Hi Sreenivasa,

I am looking for a response to the above query.

0 Premalatha Royappan over 2 years ago in reply to Kallikuppa Sreenivasa

Intellectual 910 points

Hi Sreenivasa,

I am looking for a response to the above query.

0 Premalatha Royappan over 2 years ago in reply to Kallikuppa Sreenivasa

Intellectual 910 points

Hi Sreenivasa,

I am looking for a response to the above query.

0 Premalatha Royappan over 2 years ago in reply to Kallikuppa Sreenivasa

Intellectual 910 points

Hi Sreenivasa,

I am looking for a response to the above query.

0 Premalatha Royappan over 2 years ago in reply to Kallikuppa Sreenivasa

Intellectual 910 points

Hi Sreenivasa,

I am looking for a response to the above query.

0 Premalatha Royappan over 2 years ago in reply to Kallikuppa Sreenivasa

Intellectual 910 points

Hi Sreenivasa,

I am looking for a response to the above query.

0 Premalatha Royappan over 2 years ago in reply to Kallikuppa Sreenivasa

Intellectual 910 points

Hi Sreenivasa,

I am looking for a response to the above query.

0 Kallikuppa Sreenivasa over 2 years ago in reply to Premalatha Royappan

TI__Guru**** 175744 points

Hello Premalatha Royappan,

Thank you for following up multiple times.

VoHmin value of AM625x is load dependent. A quick review indicates this should be fine.

Since you are looking at interfacing to the TPS3431SDRBR, someone from the supervisor team could help. The thread has been reassigned and please allow some time for the team to respond.

In case you need to make decision faster, ensure you do not load the SoC output by having a strong terminations. You could consider doing some quick simulations also.

Regards,

Sreenivasa

0 Patrick Shalton over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Mastermind 26180 points

Hi Premalatha,

Thanks for your patience with this. As Kallikuppa commented, using the TPS3431 should be ok as long as the SoC is not loaded (ensure that the watchdog output of the SoC is terminated with the WDI pin of the TPS3431 only).

Please consider using the TPS3435-Q1 as a watchdog timer instead, as it supports a minimum WDI Vih of 0.7 x VDD, or 2.31V at 3.3V supply.

Thanks,

Patrick

0 Kallikuppa Sreenivasa over 2 years ago in reply to Patrick Shalton

TI__Guru**** 175744 points

Hello Patrick,

Thank you for the inputs and appreciated.

Premalatha, i believe this should resolve the query.

Regards,

Sreenivasa

0 Kallikuppa Sreenivasa over 2 years ago in reply to Kallikuppa Sreenivasa

TI__Guru**** 175744 points

Hello Premalatha Royappan,

If you do not have any additional questions, please click the resolved button.

Regards,

Sreenivasa

0 Premalatha Royappan over 2 years ago in reply to Patrick Shalton

Intellectual 910 points

Hi Patrick,

We analysed TPS3435-Q1 and found that its not suitable for our requirement.We checked all variants.

Kindly let us know what would be the failure rate or guarantee that there wont be any logic incompatibility with TPS3431SDRBR,when interfaced with AM625x.Kindly confirm on this as we in the final stages of design, which would be released for fabrication soon.

0 Isa Chang over 2 years ago in reply to Premalatha Royappan

TI__Expert 3040 points

Hi Premalatha,

Would it be possible to consider using the TPS3820 as an alternative? This device performs similarly to the TPS3431 but the ViH(min) is lower at 0.7xVdd which at VDD=3.3V is 2.31V.

Thanks,

Isa

0 Premalatha Royappan over 2 years ago in reply to Isa Chang

Intellectual 910 points

Hi Isa

This IC TPS3830 does not have the equivalent functionality of TPS3431 and hence may not meet our requirements.Kindly confirm us if only one single load is connected , then is it guaranteed that Voh of watchdog would not go down below 2.64V(2.64 is vih min for processor). Pls confirm on this as you had mentioned in the before conversation that if its not loaded much there should not be any issue.

0 Trailokya Rai over 2 years ago in reply to Premalatha Royappan

TI__Genius 11401 points

Hi Premlatha

I will confrm your first query "While checking logic compatibility for WDI pin, we found for watchdog timer ViH(min) is 2.64V(0.8 × VDD).But VoHmin of AM625x is 2.4V. "

WDI pin of TPS3431 will take sub uA current, hence VOH of AM625X will not go as low as 2.4V (which is defined at 10mA). It will be close to supply voltage as there is no loading. Hnece there will not be any problem.

Regards

Trailokya

0 Kallikuppa Sreenivasa over 2 years ago in reply to Trailokya Rai

TI__Guru**** 175744 points

Hi Premlatha

Please be sure not to use strong termination in case you are using a termination.

Regards,

Sreenivasa