Ball number: P7 question about DRA746APGABCRQ1

Max CHANNG

Prodigy 120 points

I have question about ball number: P7.

Can the ESR of P7 be reduced?

In Ball number: P7 I select to use I2C3_SCL function.

I pull up 2.2K ohm.

I measure the rise time out of spec 50ns.(spec rise time: 300ns[Max])

How can I do let the rise time less than 300ns.

Thanks~

over 7 years ago

0 Stanislav Stilyanov over 7 years ago

TI__Genius 17900 points

Hi Max CHANNG,

Can you please clarify your question?

You are measuring 50ns, but want to be less than 200ns? Did you mean you measure 500ns?

How do you calculate the rise time? From which voltage level to which?

Thanks,

Stan

0 Max CHANNG over 7 years ago in reply to Stanislav Stilyanov

Prodigy 120 points

Hi Stan,

Sorry ,let me explain it again.

I measure the I2C_SCL rise time is 350ns, but the spec rise time is 300ns(Max).

I use oscilloscope(Tektronix DPO-4104) to measure the rise time, it has built-in measurement.

I pull high 2.2k ohm of 3.3vs in I2C_SCL .

How can I let the rise time less than 300ns? Change the pull high resistance?Other...?

Thanks,

0 Stanislav Stilyanov over 7 years ago in reply to Max CHANNG

TI__Genius 17900 points

I'm sorry for delayed response.

I guess it is fine to reduce resistance. However, if the capacitance of the line is too high (>100pF) you may wish to reduce it first, if you can. For example, optimizing traces on the PCB (routing), using shorter traces, using fewer I2C devices on the same bus, etc.

You may also refer to this appnote:

www.ti.com/lit/an/slva689/slva689.pdf

Best regards,

Stan