TPS3840-Q1: calculation of delay time

Hi Oscar, 

Thanks for your question!

It looks like we have the date for the max delay. Can you please let me know why do you need that information? I'm trying to see how can I support you with your inquiry. 

If you don't have any specific requirement, I think it could be a good practice to expect the delay maximum 50 us. 

I hope this  helps!

Best,

Sila Atalar 

Hi Sila,

I also suggested the costumer to use the max value. The confusing thing is that in the formula td min is suggested but this is not mentioned in the data sheet. Do any information about this? otherwise, i would just tell them to consider td max for both formulas

Thank you!

oscar

Hi Oscar, 

The delay equation has tD (no cap, min) because this is the most accurate and correct way to calculate the reset time delay. I think overall goal is provide the correct equation to our customers. For this specific datasheet it may make sense we may not need to shown no cap, min in the equations, and I would also tell them to consider td max for both formulas.

If our customer pick to use a small capacitor at CT pin (their -ln(0.36) x RCT (min) x CCT (min) will be microsecond range), then they should be adding the  internal delay in their delay calculations. 

But if they use a bigger cap at CT pin (their -ln (0.36) x RCT (min) x CCT (min) will be millisecond range, then that internal delay won't be chancing their overall delay that much since they already have bigger cap and bigger delay. 

Best Regards,

Sila Atalar

Hi Sila,

Is there a big span between Td min and max?

Because if they are using the CCT min this might have a significant impact on the overall delay...

Thanks

Oscar

That´s fine!

Thank you

Hi Oscar,

No Problem!

Best,

Sila