UCD90160A: Clock/data rise time and fall time

Sean Song

Intellectual 1640 points

Part Number: UCD90160A
Other Parts Discussed in Thread: UCD90124A

Hi expert,

My customer want to use sequencer and they want to know something about Clock/data rise time and fall time(tr and tf).

UCD90160A DATASHEET: max Tr is 120ns

UCD90124A DATASHEET: max Tr is 300ns

SMBUS Protocol: max Tr is 1000ns@ 100kHz, 300ns@ 400kHz , 120ns@ 1MHz

Customer want to know:

1 Why our UCD90160A and UCD90124A have different tr spec? And why their spec both different with SMBUS Protocol?

2 Can they use I2C whose 300ns>tr>120ns in UCD90160A? What about 1000ns>tr>300ns?

If not, what will happen if they use like this?

Thanks

Best Regards,

Sean Song

over 2 years ago

0 yihe over 2 years ago

TI__Guru 60800 points

You have old UCD90160A data sheet, we have updated it to correct the rising and falling time.

Please get it from ti.com

Regards

Yihe

0 Sean Song over 2 years ago in reply to yihe

TI__Intellectual 1640 points

Hi Yihe,

Thank you very much for the professional reply.

In updated DS, the tr is MAX 300ns for 10KHz to 400KHz.

Our customer operating frequency is 100KHz.

Their tr is 344.79ns > 300ns.

But it is fit for SMBUS Protocol: max Tr is 1000ns@ 100kHz.

So they want to know will it(tr is 344.79ns@ 100kHz , add 10% margin 380ns @ 100kHz ) affect the UCD device?

Thanks

Best Regards,

Sean Song

+1 yihe over 2 years ago in reply to Sean Song

TI__Guru 60800 points

UCD90160A is fully compliant with I2C spec.

the 300ns rising time is for 400KHz speed. if customer runs at 100KH, it is 1000ns

Regards

Yihe

0 Sean Song over 2 years ago in reply to yihe

TI__Intellectual 1640 points

Hi Yihe,

Got it.

Thank you very much.

Do all of our sequencer's I2C timing spec like this?

Thanks

Best Regards,

Sean Song

0 yihe over 2 years ago in reply to Sean Song

TI__Guru 60800 points

That's right.

Thanks

Yihe

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UCD90160A: Clock/data rise time and fall time