UCD9090-Q1: I2C bus falling time is not matched with the datasheet

Smith Chao

Part Number: UCD9090-Q1
Other Parts Discussed in Thread: UCD9090

Tool/software:

Hi TI Expert,

I'm using the UCD9090 in my automotive application. I’ve measured the I2C bus and found that the falling time does not match the datasheet specifications, though other parameters (hold time, setup time, and rising time) do meet the requirements.

How can I increase the falling time? Is it possible to ignore the falling time in this context?

I2C datasheet: www.nxp.com/.../UM10204.pdf

UCD9090 datasheet:

measured waveform:

thanks

Smith

over 1 year ago

0 yihe over 1 year ago

TI__Guru 66120 points

UCD9090 follows the standard I2C spec. The timing listed in the data sheet is for 400Khz. if you are using 100Khz, the rising time would be larger which is in the standard i2C spec.

Regards

Yihe

0 Smith Chao over 1 year ago in reply to yihe

Intellectual 255 points

Hi Yihe,

Thanks for your reply. I’m looking to increase the "falling time" on the I2C bus while ensuring that other parameters still meet the specifications.

Although we are running the I2C at 400 kHz and the rising time is within spec, we would like to improve the falling time.

thanks

Smith

0 yihe over 1 year ago in reply to Smith Chao

TI__Guru 66120 points

Your falling time is better than rising time from the waveform. What is the pull-up resistor used here?

Regards

Yihe

Power management

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UCD9090-Q1: I2C bus falling time is not matched with the datasheet