TPS652353: tFCL,tFDA

David Kim2

Part Number: TPS652353

Tool/software:

Looking at Datasheet, the min value of tfcl,tfda is 20 ns.

The manufactured board measures tFCL = 1.5ns and tFDA = 2.5ns.
Is there something wrong? Or am I wrong with the data sheet?

-Condition-

CB=0

Ch1:SDA(Yellow), Ch2:SCL(Green)

Thanks

3 months ago

0 Colin Chen 3 months ago

TI__Genius 16771 points

Hi David，

I think datasheet spec is based on Cb=400pF which is a relatively high value.

In normal condition, if the Cb is smaller than this, the tfcl,tfda would be small accorrdingly.

Hope you can understand.

Thanks,

Colin

0 David Kim2 3 months ago in reply to Colin Chen

Expert 2885 points

Hi Colin

According to the data sheet, the minimum value is 20+0.1Cb.
If so, I understood that min is 20ns when Cb=0.
But it came out smaller than 20ns, so I asked.
Can I come out as small as now?

Thanks

0 Colin Chen 3 months ago in reply to David Kim2

TI__Genius 16771 points

Will check

0 Colin Chen 3 months ago in reply to Colin Chen

TI__Genius 16771 points

Hi David,

I think SDL and SDA rising time and falling time is not the key spec. Because it depends on CB and trace length.

If you can make a effective write and read function, these two time is ok to me.

Thanks,

Colin

0 David Kim2 2 months ago in reply to Colin Chen

Expert 2885 points

Hi Colin

According to the data sheet, if the minimum value is 20ns and it goes out of the data sheet value, isn't there a problem with the I2C interface?
If the measurement is at least no problem than 20ns, request data that can be determined to be no problem.

Thanks

0 Colin Chen 2 months ago in reply to David Kim2

TI__Genius 16771 points

Hi David，

Yeah, I checked and suggested you follow the rising and falling time spec in datasheet.

You can add series resistor or / and bypass capacitors to data and clock lines to meet the requirement.

0 David Kim2 1 month ago in reply to Colin Chen

Expert 2885 points

Hi Colin

If it's okay to go outside the min value of the data sheet, shouldn't we change the min spec of the data sheet?
The data sheet of UM10204(NXP) has a min value changed to 20* (VDD/5.5V).

Thanks

0 Colin Chen 1 month ago in reply to David Kim2

TI__Genius 16771 points

Hi David,

I think for now, it is better to follow datasheet spec. Because this is a old device. I think it is ok to have a faster slew rate as long you evaluate it can connect well.

Thanks,

Colin

Power management

Power management forum

TPS652353: tFCL,tFDA