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Non Volatile RAM (F-RAM & NVSRAM) Forum Discussions

p_izard
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hello,

The DQ output level of the FM28V202A IBIS model  in Slow weak mode, is equal to 2V maximum, whatever the load, which is lower than the minimum level guaranteed by the datasheet 2.4V for -1mA and VDD=2.7V. Did we do something wrong?

Thank you in advance for your help,

Best regards

Pierre

 

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8 Replies
ritwicksharma
Moderator
Moderator
Moderator
250 sign-ins 100 replies posted 50 solutions authored

Hi @p_izard,

 

Could you please let us know how you are simulating the model? It would be better if you share the HyperLynx project or the schematic of the project.

 

Thanks,

Ritwick

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p_izard
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hi Ritwik,

Thank you for your answer. Just simulating the model with Linesim directly on a 10Kohm resistor

Best regards

Pierre

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Hi @p_izard,

 

Could you please simulate the model for typical and fast mode and let us know the results?

 

Thanks,

Ritwick

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p_izard
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hi Ritwick,

When we simulate the model on a 10Kohm load, we obtain an established level of 1.98V in Slow weak, 2.79V in typical and 3.59V in Fast strong mode. As I told you the 1.98V is below the min VOH (for IOH = -1mA and VDD>2.7V) i.e. 2.4V given by the datasheet. I hope that we will be able to obtain simulation results consistent with the datasheet and reassure ourselves in the context of the worst case analyses that we are carrying out.

Thank you in advance for your help,

Best regards

Pierre

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Hi @p_izard,

 

Voltages used for the model generation:

> Slow weak- 2 V

> Typical- 2.8 V

> Fast strong- 3.6 V

 

This is the reason you are observing those voltages. I hope this clarifies your doubt.

 

Thanks,

Ritwick

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p_izard
Level 1
Level 1
5 sign-ins First reply posted First question asked

Hi Ritwick

In general, the models are configured to have a low and slow output with a 3V supply (for a supply of 3.3V in typical) in Slow Weak mode. The fact that the output in Slow Weak mode is below the minimum specified 2.4V for a power supply of 2.7V min, means that the model is not usable in this mode. Couldn't you modify the model (or tell us how to do it) so that the level in Slow weak mode complies with the specifications, equal to 2.4V for example. Similarly we expect the output level in Typical mode to be equal to that generally observed for a 3.3V supply.

Thank you in advance for your help,

Best regards

Pierre

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Hi @p_izard,

 

As for our model for slow weak mode, the voltage is 2 V (<2.7 V). Could you please check if you comply with the VOH2 spec, as this does not have any condition on VDD?

 

ritwicksharma_0-1671798364833.png

 

Thanks,

Ritwick

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p_izard
Level 1
Level 1
5 sign-ins First reply posted First question asked

Ritwick,

Yes, we comply with the VOH2 spec (|IOH| is lower than 100uA). I hope you will be able to modify the model or we can do it ourselves with your help. We could put the typical level at 3.3V - 0.1V as the established current is much lower than 100uA, and the Slow weak level at 2.8V (3V - 0.2V).

Best regards

Pierre

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